Sytchkova, A., Belosludtsev, A., Volosevičienė, L., Juškėnas, R. & Simniškis, R. Optical, structural and electrical properties of sputtered ultrathin chromium films. Optical Materials 121, 111530, https://doi.org/10.1016/j.optmat.2021.111530 (2021).

Rowe, D. J., Smith, D. & Wilkinson, J. S. Complex refractive index spectra of whole blood and aqueous solutions of anticoagulants, analgesics and buffers in the mid-infrared. Scientific Reports 7, https://doi.org/10.1038/s41598-017-07842-0 (2017).

Jellison, G., Haynes, T. & Burke, H. Optical functions of silicon-germanium alloys determined using spectroscopic ellipsometry. Optical Materials 2, 105–117, https://doi.org/10.1016/0925-3467(93)90035-y (1993).

Nigara, Y. Measurement of the optical constants of yttrium oxide. Japanese Journal of Applied Physics 7, 404, https://doi.org/10.1143/jjap.7.404 (1968).

Milam, D., Weber, M. J. & Glass, A. J. Nonlinear refractive index of fluoride crystals. Applied Physics Letters 31, 822–825, https://doi.org/10.1063/1.89561 (1977).

Mathewson, A. G. & Myers, H. P. Absolute values of the optical constants of some pure metals. Physica Scripta 4, 291–292, https://doi.org/10.1088/0031-8949/4/6/009 (1971).

Kato, K. & Umemura, N. Sellmeier equations for GaS and GaSe and their applications to the nonlinear optics in GaSxSe1-x. Optics Letters 36, 746, https://doi.org/10.1364/ol.36.000746 (2011).

Yakubovsky, D. I., Arsenin, A. V., Stebunov, Y. V., Fedyanin, D. Y. & Volkov, V. S. Optical constants and structural properties of thin gold films. Optics Express 25, 25574, https://doi.org/10.1364/oe.25.025574 (2017).

Yakubovsky, D. I. et al. Ultrathin and ultrasmooth gold films on monolayer MoS2. Advanced Materials Interfaces 6, https://doi.org/10.1002/admi.201900196 (2019).

Lajaunie, L., Boucher, F., Dessapt, R. & Moreau, P. Strong anisotropic influence of local-field effects on the dielectric response of α-MoO3. Physical Review B 88, https://doi.org/10.1103/physrevb.88.115141 (2013).

Numericalapertureof lens

Das, S., Bhar, G. C., Gangopadhyay, S. & Ghosh, C. Linear and nonlinear optical properties of ZnGeP2 crystal for infrared laser device applications: revisited. Applied Optics 42, 4335, https://doi.org/10.1364/ao.42.004335 (2003).

Bhar, G. C. & Ghosh, G. Temperature-dependent Sellmeier coefficients and coherence lengths for some chalcopyrite crystals. Journal of the Optical Society of America 69, 730, https://doi.org/10.1364/josa.69.000730 (1979).

French, R. H. et al. Optical properties of materials for concentrator photovoltaic systems. In 2009 34th IEEE Photovoltaic Specialists Conference (PVSC), https://doi.org/10.1109/pvsc.2009.5411657 (IEEE, 2009).

Pigeon, J. J., Tochitsky, S. Y., Welch, E. C. & Joshi, C. Measurements of the nonlinear refractive index of air, N2, and O2 at 10 μm using four-wave mixing. Optics Letters 41, 3924, https://doi.org/10.1364/ol.41.003924 (2016).

Guo, Z. et al. Complete dielectric tensor and giant optical anisotropy in quasi-one-dimensional ZrTe5. ACS Materials Letters 3, 525–534, https://doi.org/10.1021/acsmaterialslett.1c00026 (2021).

Zhang, X., Qiu, J., Li, X., Zhao, J. & Liu, L. Complex refractive indices measurements of polymers in visible and near-infrared bands. Applied Optics 59, 2337, https://doi.org/10.1364/ao.383831 (2020).

Smith, P. L., Huber, M. C. E. & Parkinson, W. H. Refractivities of H2, He, O2, CO, and Kr for 168 ≤ λ ≤ 288 nm. Physical Review A 13, 1422–1434, https://doi.org/10.1103/physreva.13.1422 (1976).

Dore, P. et al. Infrared properties of chemical-vapor deposition polycrystalline diamond windows. Applied Optics 37, 5731, https://doi.org/10.1364/ao.37.005731 (1998).

Ives, H. E. & Briggs, H. B. The optical constants of sodium. Journal of the Optical Society of America 27, 181, https://doi.org/10.1364/josa.27.000181 (1937).

Radhakrishnan, T. The dispersion, briefringence and optical activity of quartz. Proceedings of the Indian Academy of Sciences - Section A 25, https://doi.org/10.1007/bf03171408 (1947).

SPECS: ... thermal_dispersion: - type: “Schott formula” coefficients: 1.86e-06 1.31e-08 −1.37e-11 4.34e-07 6.27e-10 0.17 nd: 1.5168 Vd: 64.17 glass_code: 517642.251 glass_status: standard ... acid_resistance: 1.0 alkali_resistance: 2.3 phosphate_resistance: 2.3

Umegaki, S., Tanaka, S.-I., Uchiyama, T. & Yabumoto, S. Refractive indices of lithium iodate between 0.4 and 2.2 μ. Optics Communications 3, 244–245, https://doi.org/10.1016/0030-4018(71)90013-7 (1971).

Rosker, M., Cheng, K. & Tang, C. Practical urea optical parametric oscillator for tunable generation throughout the visible and near-infrared. IEEE Journal of Quantum Electronics 21, 1600–1606, https://doi.org/10.1109/jqe.1985.1072557 (1985).

Beliaev, L. Y., Shkondin, E., Lavrinenko, A. V. & Takayama, O. Erratum: “Thickness-dependent optical properties of aluminum nitride films for mid-infrared wavelengths” [J. Vac. Sci. Technol. A 39, 043408 (2021)]. Journal of Vacuum Science & Technology A 40, https://doi.org/10.1116/6.0001574 (2022).

User input: At the present maturity level of the project, most new data sources are recommended by users. Researchers often provide us with data in a format ready-to-include in the refractiveindex.info dataset as soon as the data are first published.

r(Airy) is the Airy radius, λ is the wavelength of the illuminating light, and NA(Obj) is the objective´s numerical aperture (objective aperture = condenser aperture). The numerical aperture depends on the aperture angle of the illumination entering the objective aperture, as well as the refractive index of the imaging medium:

Bond, W. L. Measurement of the refractive indices of several crystals. Journal of Applied Physics 36, 1674–1677, https://doi.org/10.1063/1.1703106 (1965).

Chen, L. & Lynch, D. W. The optical properties of AuAl2 and PtAl2. physica status solidi (b) 148, 387–394, https://doi.org/10.1002/pssb.2221480136 (1988).

Inagaki, T., Arakawa, E. T. & Williams, M. W. Optical properties of liquid mercury. Physical Review B 23, 5246–5262, https://doi.org/10.1103/physrevb.23.5246 (1981).

Fernández-Perea, M. et al. Determination of optical constants of scandium films in the 20–1000 eV range. Journal of the Optical Society of America A 23, 2880, https://doi.org/10.1364/josaa.23.002880 (2006).

- SHELF: main name: “MAIN - simple inorganic materials” content: - DIVIDER: “Al - Aluminates, Aluminium garnets” - BOOK: BeAl2O4 name: “BeAl2O4 (Beryllium aluminate, chrysoberyl)” info: “main/BeAl2O4.html” content: - PAGE: Adair name: “Adair 1989” data: “main/BeAl2O4/Adair.yml” ... - BOOK: MgAl2O4 name: “MgAl2O4 (Magnesium aluminate, spinel)” info: “main/MgAl2O4.html” content: - PAGE: Flom name: “Flom et al. 2015” data: “main/MgAl2O4/Flom.yml” - PAGE: Adair name: “Adair et al. 1989” data: “main/MgAl2O4/Adair.yml” ...

Kabelka, V. I., Piskarskas, A. S., Stabinis, A. Y. & Sher, R. L. Group matching of interacting light pulses in nonlinear crystals. Soviet Journal of Quantum Electronics 5, 255–256, https://doi.org/10.1070/qe1975v005n02abeh010943 (1975).

Zhang, X. et al. Optimizing the design of the vapor-deposited CsPbCl3-based optoelectronic devices via simulations and experiments. Advanced Functional Materials 2310945, https://doi.org/10.1002/adfm.202310945 (2023).

Kozma, I. Z., Krok, P. & Riedle, E. Direct measurement of the group-velocity mismatch and derivation of the refractive-index dispersion for a variety of solvents in the ultraviolet. Journal of the Optical Society of America B 22, 1479, https://doi.org/10.1364/josab.22.001479 (2005).

Sato, K. & Adachi, S. Optical properties of ZnTe. Journal of Applied Physics 73, 926–931, https://doi.org/10.1063/1.353305 (1993).

Zheng, Q., Wang, X. & Thompson, D. Temperature-dependent optical properties of monocrystalline CaF2, BaF2, and MgF2. Optical Materials Express 13, 2380, https://doi.org/10.1364/ome.496246 (2023).

Kato, K., Badikov, V. V., Miyata, K. & Petrov, V. Refined Sellmeier equations for BaGa4S7. Applied Optics 60, 6600, https://doi.org/10.1364/ao.430424 (2021).

DATA: - type: formula 2 wavelength_range: 0.3 2.5 coefficients: 0 1.03961212 0.00600069867 0.231792344... - type: tabulated k data: | 0.300 2.8607E-06 0.310 1.3679E-06 0.320 6.6608E-07 ...

Heitmann, W. & Ritter, E. Production and properties of vacuum evaporated films of thorium fluoride. Applied Optics 7, 307, https://doi.org/10.1364/ao.7.000307 (1968).

Marple, D. T. F. Refractive index of ZnSe, ZnTe, and CdTe. Journal of Applied Physics 35, 539–542, https://doi.org/10.1063/1.1713411 (1964).

Ermolaev, G. A., Yakubovsky, D. I., Stebunov, Y. V., Arsenin, A. V. & Volkov, V. S. Spectral ellipsometry of monolayer transition metal dichalcogenides: Analysis of excitonic peaks in dispersion. Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena 38, https://doi.org/10.1116/1.5122683 (2019).

Yim, C. et al. Investigation of the optical properties of MoS2 thin films using spectroscopic ellipsometry. Applied Physics Letters 104, 103114, https://doi.org/10.1063/1.4868108 (2014).

Wu, S.-T. Refractive index dispersions of liquid crystals. Optical Engineering 32, 1775, https://doi.org/10.1117/12.143988 (1993).

Rosenblatt, G., Simkhovich, B., Bartal, G. & Orenstein, M. Nonmodal plasmonics: Controlling the forced optical response of nanostructures. Physical Review X 10, https://doi.org/10.1103/physrevx.10.011071 (2020).

Oguntoye, I. O. et al. Continuously tunable optical modulation using vanadium dioxide huygens metasurfaces. ACS Applied Materials & Interfaces 15, 41141–41150, https://doi.org/10.1021/acsami.3c08493 (2023).

Schubert, M. et al. Optical constants of GaxIn1-xP lattice matched to GaAs. Journal of Applied Physics 77, 3416–3419, https://doi.org/10.1063/1.358632 (1995).

Ermolaev, G. et al. Topological phase singularities in atomically thin high-refractive-index materials. Nature Communications 13, https://doi.org/10.1038/s41467-022-29716-4 (2022).

Kawashima, T., Yoshikawa, H., Adachi, S., Fuke, S. & Ohtsuka, K. Optical properties of hexagonal GaN. Journal of Applied Physics 82, 3528–3535, https://doi.org/10.1063/1.365671 (1997).

Vuye, G. et al. Temperature dependence of the dielectric function of silicon using in situ spectroscopic ellipsometry. Thin Solid Films 233, 166–170, https://doi.org/10.1016/0040-6090(93)90082-z (1993).

Tkachenko, V. et al. Nematic liquid crystal optical dispersion in the visible-near infrared range. Molecular Crystals and Liquid Crystals 454, 263/[665]–271/[673], https://doi.org/10.1080/15421400600655816 (2006).

Flom, S. R., Beadie, G., Bayya, S. S., Shaw, B. & Auxier, J. M. Ultrafast z-scan measurements of nonlinear optical constants of window materials at 772, 1030, and 1550 nm. Applied Optics 54, F123, https://doi.org/10.1364/ao.54.00f123 (2015).

Ball, J. M. et al. Optical properties and limiting photocurrent of thin-film perovskite solar cells. Energy & Environmental Science 8, 602–609, https://doi.org/10.1039/c4ee03224a (2015).

Sani, E. & Dell’Oro, A. Corrigendum to “Optical constants of ethylene glycol over an extremely wide spectral range [opt. mater. 37 (2014) 36–41]. Optical Materials 48, 281, https://doi.org/10.1016/j.optmat.2015.06.039 (2015).

Treharne, R. E. et al. Optical design and fabrication of fully sputtered CdTe/CdS solar cells. Journal of Physics: Conference Series 286, 012038, https://doi.org/10.1088/1742-6596/286/1/012038 (2011).

Aftenieva, O. et al. Lasing by template-assisted self-assembled quantum dots. Advanced Optical Materials 11, https://doi.org/10.1002/adom.202202226 (2023).

The image formed by a perfect, aberration-free objective lens at the intermediate image plane of a microscope is a diffraction pattern with a very specific intensity distribution. This tutorial explores the effects of the objective´s numerical aperture (NA) on the diffraction pattern and the resolution of a microscope. The three-dimensional representation of the diffraction pattern is the Point-Spread-Function (PSF) which, in a coma- and/or astigmatism-free system, is symmetrically periodic both along the optical axis, and radially across the image plane. This diffraction pattern can be sectioned in the focal plane to produce a two-dimensional diffraction pattern, having a bright circular disk surrounded by an alternating series of bright and dark higher-order diffraction rings whose intensity decreases with distance from the central disk, the so-called Airy disk. Under visual microscopical observation, only two or three of the circular luminous rings are usually visible in the intermediate image plane.

DATA: – type: formula 1 wavelength_range: 0.21 6.7 coefficients: 0 0.6961663 0.0684043 0.4079426... SPECS: n_is_absolute: false wavelength_is_vacuum: false

Gupta, V. et al. Advanced colloidal sensors enabled by an out-of-plane lattice resonance. Advanced Photonics Research 3, https://doi.org/10.1002/adpr.202200152 (2022).

Ermolaev, G. A. et al. Express determination of thickness and dielectric function of single-walled carbon nanotube films. Applied Physics Letters 116, https://doi.org/10.1063/5.0012933 (2020).

Malitson, I. H. A redetermination of some optical properties of calcium fluoride. Applied Optics 2, 1103, https://doi.org/10.1364/ao.2.001103 (1963).

Adair, R., Chase, L. L. & Payne, S. A. Nonlinear refractive index of optical crystals. Physical Review B 39, 3337–3350, https://doi.org/10.1103/physrevb.39.3337 (1989).

Singh, S., Remeika, J. P. & Potopowicz, J. R. Nonlinear optical properties of ferroelectric lead titanate. Applied Physics Letters 20, 135–137, https://doi.org/10.1063/1.1654078 (1972).

Rollefson, R. & Havens, R. Index of refraction of methane in the infra-red and the dipole moment of the CH bond. Physical Review 57, 710–717, https://doi.org/10.1103/physrev.57.710 (1940).

Walling, J., Peterson, O., Jenssen, H., Morris, R. & O’Dell, E. Tunable alexandrite lasers. IEEE Journal of Quantum Electronics 16, 1302–1315, https://doi.org/10.1109/jqe.1980.1070430 (1980).

Joseph, S., Sarkar, S. & Joseph, J. Grating-coupled surface plasmon-polariton sensing at a flat metal–analyte interface in a hybrid-configuration. ACS Applied Materials & Interfaces 12, 46519–46529, https://doi.org/10.1021/acsami.0c12525 (2020).

García-Cortés, S. et al. Transmittance and optical constants of Lu films in the 3–1800 eV spectral range. Journal of Applied Physics 108, https://doi.org/10.1063/1.3481062 (2010).

Boyd, G. D., Buehler, E. & Storz, F. G. Linear and nonlinear optical properties of ZnGeP2 and CdSe. Applied Physics Letters 18, 301–304, https://doi.org/10.1063/1.1653673 (1971).

Old, J. G., Gentili, K. L. & Peck, E. R. Dispersion of carbon dioxide. Journal of the Optical Society of America 61, 89, https://doi.org/10.1364/josa.61.000089 (1971).

Williams, P. A. et al. Optical, thermo-optic, electro-optic, and photoelastic properties of bismuth germanate (Bi4Ge3O12). Applied Optics 35, 3562, https://doi.org/10.1364/ao.35.003562 (1996).

Rodríguez-de Marcos, L. V., Larruquert, J. I., Méndez, J. A. & Aznárez, J. A. Self-consistent optical constants of MgF2, LaF3, and CeF3 films. Optical Materials Express 7, 989, https://doi.org/10.1364/ome.7.000989 (2017).

Gao, L., Lemarchand, F. & Lequime, M. Comparison of different dispersion models for single layer optical thin film index determination. Thin Solid Films 520, 501–509, https://doi.org/10.1016/j.tsf.2011.07.028 (2011).

Arakawa, E. T., Williams, M. W., Ashley, J. C. & Painter, L. R. The optical properties of kapton: Measurement and applications. Journal of Applied Physics 52, 3579–3582, https://doi.org/10.1063/1.329140 (1981).

Myers, T. L. et al. Accurate measurement of the optical constants n and k for a series of 57 inorganic and organic liquids for optical modeling and detection. Applied Spectroscopy 72, 535–550, https://doi.org/10.1177/0003702817742848 (2017).

Every YAML data file primarily consists of two mandatory fields: REFERENCES and DATA. REFERENCES cite the source of the data, while DATA provides the values of the optical constants. There are also two optional fields, COMMENTS and SPECS, offering additional context and structured information respectively.

Numericalapertureof microscope

Aguilar, O., de Castro, S., Godoy, M. P. F. & Rebello Sousa Dias, M. Optoelectronic characterization of Zn1-xCdxO thin films as an alternative to photonic crystals in organic solar cells. Optical Materials Express 9, 3638, https://doi.org/10.1364/ome.9.003638 (2019).

Al-Kuhaili, M. Optical properties of hafnium oxide thin films and their application in energy-efficient windows. Optical Materials 27, 383–387, https://doi.org/10.1016/j.optmat.2004.04.014 (2004).

Burnett, J. H., Kaplan, S. G., Stover, E. & Phenis, A. Refractive index measurements of Ge. In LeVan, P. D., Sood, A. K., Wijewarnasuriya, P. & D’Souza, A. I. (eds.) Infrared Sensors, Devices, and Applications VI, https://doi.org/10.1117/12.2237978 (SPIE, 2016).

Zollner, S., Lin, C., Schönherr, E., Böhringer, A. & Cardona, M. The dielectric function of AlSb from 1.4 to 5.8 eV determined by spectroscopic ellipsometry. Journal of Applied Physics 66, 383–387, https://doi.org/10.1063/1.343888 (1989).

Ferrini, R., Patrini, M. & Franchi, S. Optical functions from 0.02 to 6 eV of AlxGa1-xSb/GaSb epitaxial layers. Journal of Applied Physics 84, 4517–4524, https://doi.org/10.1063/1.368677 (1998).

Pierce, D. T. & Spicer, W. E. Electronic structure of amorphous Si from photoemission and optical studies. Physical Review B 5, 3017–3029, https://doi.org/10.1103/physrevb.5.3017 (1972).

Adachi, S. & Taguchi, T. Optical properties of ZnSe. Physical Review B 43, 9569–9577, https://doi.org/10.1103/physrevb.43.9569 (1991).

Nyakuchena, M., Juntunen, C., Shea, P. & Sung, Y. Refractive index dispersion measurement in the short-wave infrared range using synthetic phase microscopy. Physical Chemistry Chemical Physics 25, 23141–23149, https://doi.org/10.1039/d3cp03158f (2023).

Loria, S. Über die dispersion des lichtes in gasförmigen kohlenwasserstoffen. Annalen der Physik 334, 605–622, https://doi.org/10.1002/andp.19093340809 (1909).

Sarkar, S. et al. Enhanced figure of merit via hybridized guided-mode resonances in 2d-metallic photonic crystal slabs. Advanced Optical Materials 10, https://doi.org/10.1002/adom.202200954 (2022).

Rakić, A. D., Djurišić, A. B., Elazar, J. M. & Majewski, M. L. Optical properties of metallic films for vertical-cavity optoelectronic devices. Applied Optics 37, 5271, https://doi.org/10.1364/ao.37.005271 (1998).

Weiting, F. & Yixun, Y. Temperature effects on the refractive index of lead telluride and zinc selenide. Infrared Physics 30, 371–373, https://doi.org/10.1016/0020-0891(90)90055-z (1990).

Arndt, D. P. et al. Multiple determination of the optical constants of thin-film coating materials. Applied Optics 23, 3571, https://doi.org/10.1364/ao.23.003571 (1984).

Schröter, H. Über die brechungsindizes einiger schwermetallhalogenide im sichtbaren und die berechnung von interpolationsformeln für den dispersionsverlauf. Zeitschrift für Physik 67, 24–36, https://doi.org/10.1007/bf01391040 (1931).

Initiatives to amalgamate scattered information on optical constants resulted in seminal works like Palik’s comprehensive compilation3, offering structured and uniformly formatted data. Though monumental, the rapid advancement of technology and research methodologies signposted the need for a more dynamic, easily accessible repository of n and k values. This need intensified with the emergence of high-peak-power lasers, highlighting the critical role of the nonlinear refractive index, n2, in decoding material behavior under intense light. n2 characterizes the refractive index’s variation with the optical field intensity I, expressed as n = n0 + n2I, where n0 is the refractive index at zero intensity.

Wang, S. et al. 4H-SiC: a new nonlinear material for midinfrared lasers. Laser & Photonics Reviews 7, 831–838, https://doi.org/10.1002/lpor.201300068 (2013).

Rakić, A. D. & Majewski, M. L. Modeling the optical dielectric function of GaAs and AlAs: Extension of Adachi’s model. Journal of Applied Physics 80, 5909–5914, https://doi.org/10.1063/1.363586 (1996).

Kawka, P. A. & Buckius, R. O. Optical properties of polyimide films in the infrared. International Journal of Thermophysics 22, 517–534, https://doi.org/10.1023/a:1010797620483 (2001).

Numericalapertureof objective lens

Ghosal, S., Ebert, J. L. & Self, S. A. The infrared refractive indices of CHBr3, CCl4 and CS2. Infrared Physics 34, 621–628, https://doi.org/10.1016/0020-0891(93)90120-v (1993).

User feedback: This is our strongest defense line in assuring the integrity of the data records. The users report errors via the GitHub page of the refractiveindex.info project or by directly contacting the maintainer. Each report is analyzed, and necessary corrections are promptly implemented.

Ermolaev, G. et al. Giant and tunable excitonic optical anisotropy in single-crystal halide perovskites. Nano Letters 23, 2570–2577, https://doi.org/10.1021/acs.nanolett.2c04792 (2023).

Grudinin, D. V. et al. Hexagonal boron nitride nanophotonics: a record-breaking material for the ultraviolet and visible spectral ranges. Materials Horizons 10, 2427–2435, https://doi.org/10.1039/d3mh00215b (2023).

Eimerl, D., Davis, L., Velsko, S., Graham, E. K. & Zalkin, A. Optical, mechanical, and thermal properties of barium borate. Journal of Applied Physics 62, 1968–1983, https://doi.org/10.1063/1.339536 (1987).

Griesmann, U. & Burnett, J. H. Refractivity of nitrogen gas in the vacuum ultraviolet. Optics Letters 24, 1699, https://doi.org/10.1364/ol.24.001699 (1999).

The ‘info’ entry specifies paths to additional HTML-based information, enabling users to access in-depth insights. Each ‘PAGE’ entry is linked with a ‘data’ field, pointing to the exact location of the data record’s YAML file within the dataset. The ‘name’ entry provides a “long” name for a shelf, book, or page in HTML typesetting. Paths to the data files for the linear (nk) and nonlinear (n2) subsets of the database, as well as to the HTML files with additional information (info), are relative to the data-nk, data-n2, and info directories, respectively, all located in the database’s root directory.

Please note that in some cases, you may be prompted to enter your login credentials again to access certain areas or resources within our training platform.

Testing of data file adherence to the YAML standard: This is typically performed by verifying the as-expected operation of several scripts used to access the data and relying on standardized YAML processing libraries. Error or warning messages generated by these scripts indicate a problem in the data record file that must be identified and corrected.

Amotchkina, T., Trubetskov, M., Hahner, D. & Pervak, V. Characterization of e-beam evaporated Ge, YbF3, ZnS, and LaF3 thin films for laser-oriented coatings. Applied Optics 59, A40, https://doi.org/10.1364/ao.59.000a40 (2019).

Schnabel, V., Spolenak, R., Doebeli, M. & Galinski, H. Structural color sensors with thermal memory: Measuring functional properties of Ti-based nitrides by eye. Advanced Optical Materials 6, https://doi.org/10.1002/adom.201800656 (2018).

It is essential to note that the data encapsulated within the refractiveindex.info dataset is meticulously curated from publicly available sources. This includes peer-reviewed journals, authoritative books, and manufacturer datasheets, ensuring that the dataset is not only expansive but also anchored in reliability and veracity. Each data record within the dataset explicitly cites the source, offering users a pathway to delve deeper into the original data and its context. All journal papers from which data are presently used in the refractiveindex.info dataset, excluding those without a DOI identifier, are included in the following reference list6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,373,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471.

Ermolov, A., Mak, K. F., Frosz, M. H., Travers, J. C. & Russell, P. S. J. Supercontinuum generation in the vacuum ultraviolet through dispersive-wave and soliton-plasma interaction in a noble-gas-filled hollow-core photonic crystal fiber. Physical Review A 92, https://doi.org/10.1103/physreva.92.033821 (2015).

Ewbank, M. D. et al. The temperature dependence of optical and mechanical properties of Tl3AsSe3. Journal of Applied Physics 51, 3848–3852, https://doi.org/10.1063/1.328128 (1980).

Bright, T. J. et al. Infrared optical properties of amorphous and nanocrystalline Ta2O5 thin films. Journal of Applied Physics 114, https://doi.org/10.1063/1.4819325 (2013).

Fernández-Perea, M. et al. Optical constants of evaporation-deposited silicon monoxide films in the 7.1–800 eV photon energy range. Journal of Applied Physics 105, https://doi.org/10.1063/1.3123768 (2009).

Dalzell, W. H. & Sarofim, A. F. Optical constants of soot and their application to heat-flux calculations. Journal of Heat Transfer 91, 100–104, https://doi.org/10.1115/1.3580063 (1969).

Cuthbertson, C. & Cuthbertson, M. On the refraction and dispersion of neon. Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character 83, 149–151, https://doi.org/10.1098/rspa.1910.0001 (1910).

Takaoka, E. & Kato, K. Thermo-optic dispersion formula for AgGaS2. Applied Optics 38, 4577, https://doi.org/10.1364/ao.38.004577 (1999).

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Ozaki, S. & Adachi, S. Spectroscopic ellipsometry and thermoreflectance of GaAs. Journal of Applied Physics 78, 3380–3386, https://doi.org/10.1063/1.359966 (1995).

Grace, E., Butcher, A., Monroe, J. & Nikkel, J. A. Index of refraction, Rayleigh scattering length, and Sellmeier coefficients in solid and liquid argon and xenon. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 867, 204–208, https://doi.org/10.1016/j.nima.2017.06.031 (2017).

Adachi, S. Optical dispersion relations for GaP, GaAs, GaSb, InP, InAs, InSb, AlxGa1-xAs, and In1-xGaxAsyP1-y. Journal of Applied Physics 66, 6030–6040, https://doi.org/10.1063/1.343580 (1989).

Numericalapertureunit

Pestryakov, E. V. et al. Physical properties of BeAl6O10 single crystals. Journal of Applied Physics 82, 3661–3666, https://doi.org/10.1063/1.365728 (1997).

Bassarab, V. V., Shalygin, V. A., Shakhmin, A. A., Sokolov, V. S. & Kropotov, G. I. Spectroscopy of a borosilicate crown glass in the wavelength range of 0.2 μm–15 cm. Journal of Optics 25, 065401, https://doi.org/10.1088/2040-8986/accaf9 (2023).

Hass, G., Jacobus, G. F. & Hunter, W. R. Optical properties of evaporated iridium in the vacuum ultraviolet from 500 Å to 2000 Å. Journal of the Optical Society of America 57, 758, https://doi.org/10.1364/josa.57.000758 (1967).

Cross-references from the initial list of data sources: In the next iteration, we scan for references to other publications in the sources identified in the previous step (usually, scientific papers reporting new measurements describe previous works on similar topics).

Hass, G. & Salzberg, C. D. Optical properties of silicon monoxide in the wavelength region from 0.24 to 14.0 microns. Journal of the Optical Society of America 44, 181, https://doi.org/10.1364/josa.44.000181 (1954).

Bass, M. et al. (eds). Handbook of Optics, Volume IV: Optical Properties of Materials, Nonlinear Optics, Quantum Optics. (McGraw-Hill, New York, 2009).

Sinnock, A. C. & Smith, B. L. Refractive indices of the condensed inert gases. Physical Review 181, 1297–1307, https://doi.org/10.1103/physrev.181.1297 (1969).

Polyanskiy, M. N. et al. Post-compression of long-wave infrared 2 picosecond sub-terawatt pulses in bulk materials. Optics Express 29, 31714, https://doi.org/10.1364/oe.434238 (2021).

Franta, D., Nečas, D. & Ohlídal, I. Universal dispersion model for characterization of optical thin films over a wide spectral range: application to hafnia. Applied Optics 54, 9108, https://doi.org/10.1364/ao.54.009108 (2015).

Klein, C. A. Room-temperature dispersion equations for cubic zinc sulfide. Applied Optics 25, 1873, https://doi.org/10.1364/ao.25.001873 (1986).

Fernández-Perea, M. et al. Optical constants of electron-beam evaporated boron films in the 6.8–900 eV photon energy range. Journal of the Optical Society of America A 24, 3800, https://doi.org/10.1364/josaa.24.003800 (2007).

The complex index of refraction \(\widetilde{n}=n+ik\) is essential for understanding the optical properties of materials due to its close relation with the relative permittivity εr (\({\varepsilon }_{r}={\widetilde{n}}^{2}\) in the case of non-magnetic materials1). In this context, n is the phase velocity ratio of light in a vacuum to that in the material, representing refraction. The extinction coefficient k measures absorption. The absorption coefficient α can be expressed as \(\alpha =4\pi k/\lambda \), with λ representing the light’s wavelength.

Kiyoshi Kato, K. K. & Hiromichi Shirahata, H. S. Nonlinear ir generation in AgGaS2. Japanese Journal of Applied Physics 35, 4645, https://doi.org/10.1143/jjap.35.4645 (1996).

Bieniewski, T. M. & Czyzak, S. J. Refractive indexes of single hexagonal ZnS and CdS crystals. Journal of the Optical Society of America 53, 496, https://doi.org/10.1364/josa.53.000496 (1963).

Song, B. et al. Determination of dielectric functions and exciton oscillator strength of two-dimensional hybrid perovskites. ACS Materials Letters 3, 148–159, https://doi.org/10.1021/acsmaterialslett.0c00505 (2020).

Yang, H. U. et al. Optical dielectric function of silver. Physical Review B 91, https://doi.org/10.1103/physrevb.91.235137 (2015).

The n2explorer.py script’s graphical user interface facilitates visual navigation through the n2 data. The nkexplorer.py script provides a similar interface for exploring linear optical constants.

Larruquert, J. I., Rodríguez-de Marcos, L. V., Méndez, J. A., Martin, P. J. & Bendavid, A. High reflectance ta-C coatings in the extreme ultraviolet. Optics Express 21, 27537, https://doi.org/10.1364/oe.21.027537 (2013).

Hanson, F. & Dick, D. Blue parametric generation from temperature-tuned LiB3O5. Optics Letters 16, 205, https://doi.org/10.1364/ol.16.000205 (1991).

Whang, U. S., Arakawa, E. T. & Callcott, T. A. Optical properties of Cs for photons of energy 36–96 eV. Journal of the Optical Society of America 61, 740, https://doi.org/10.1364/josa.61.000740 (1971).

Errors in converting original data to standardized data records occasionally occur and are typically reported by users. All efforts are made to implement necessary corrections promptly via regular updates of the dataset.

M.N.P. conceptualized, created, and has maintained the refractiveindex.info database throughout the years, ensuring its continuous update and improvement to meet the evolving needs of the optics and photonics community. The compilation, verification, and organization of the data, as well as the development and maintenance of the associated tools included with the database, were all carried out by M.N.P. The invaluable feedback and data contributions from the user community have played a crucial role in enhancing the comprehensiveness and accuracy of the database.

The subsequent sections delve into the methods employed for collecting the data included in refractiveindex.info, detailing the file format used for storing data records and our approach to verifying dataset integrity. We then highlight the application aspects of this dataset, illustrated with an example of an interactive data browser, and conclude with a statement on data availability.

Olmon, R. L. et al. Optical dielectric function of gold. Physical Review B 86, https://doi.org/10.1103/physrevb.86.235147 (2012).

The development of the n2 segment of the refractiveindex.info database was facilitated by grants from the US Department of Energy Accelerator Stewardship Program. Originally a part of the Office of High Energy Physics (HEP), this program is now under the purview of the Accelerator Research & Development and Production (ARDAP) office. The author extends heartfelt appreciation to the multitude of contributors from the scientific and engineering realms. Their contributions, spanning data submissions, error reporting, and invaluable insights, have been instrumental in the refinement and expansion of the database. The collective engagement of this dedicated community has been pivotal in elevating the database to its current stature of utility and comprehensiveness.

Fernández-Perea, M. et al. Transmittance and optical constants of Pr films in the 4–1600ev spectral range. Journal of Applied Physics 103, https://doi.org/10.1063/1.2939269 (2008).

Ciesielski, A., Skowronski, L., Trzcinski, M. & Szoplik, T. Controlling the optical parameters of self-assembled silver films with wetting layers and annealing. Applied Surface Science 421, 349–356, https://doi.org/10.1016/j.apsusc.2017.01.039 (2017).

Verification and documentation of data attribution: We trace the origin of the data to the first publication where it appeared and include the corresponding information in the data record file, ensuring users can validate the origins of the data. If the original data were re-analyzed, or a combination of data from multiple sources was used in a later publication (for example, to produce a dispersion formula valid in an extended wavelength range), this fact is also documented in the REFERENCES field of the data record file.

Moutzouris, K., Stavrakas, I., Triantis, D. & Enculescu, M. Temperature-dependent refractive index of potassium acid phthalate (KAP) in the visible and near-infrared. Optical Materials 33, 812–816, https://doi.org/10.1016/j.optmat.2010.12.021 (2011).

Kato, K., Petrov, V. & Umemura, N. Phase-matching properties of yellow color HgGa2S4 for shg and sfg in the 0.944–10.5910 μm range. Applied Optics 55, 3145, https://doi.org/10.1364/ao.55.003145 (2016).

In the initial example, the SPECS entries clarify that the refractive index is not absolute and is measured relative to air, that the wavelength is gauged under atmospheric conditions rather than in vacuum, and that the data is applicable at a temperature of 20 °C. In the preceding example concerning n2, the SPECS delineate the use of the Z-scan measurement method, specifying pulse durations of 280 fs, 140 fs, and 97 fs for the corresponding data points. Furthermore, the SPECS section is adaptable to encapsulate an enhanced depth of information regarding the material, as illustrated in the forthcoming example for SCHOTT N-BK7 glass:

Kulikova, D. P. et al. Optical properties of tungsten trioxide, palladium, and platinum thin films for functional nanostructures engineering. Optics Express 28, 32049, https://doi.org/10.1364/oe.405403 (2020).

Ninomiya, S. & Adachi, S. Optical properties of cubic and hexagonal CdSe. Journal of Applied Physics 78, 4681–4689, https://doi.org/10.1063/1.359815 (1995).

Aftenieva, O. et al. Directional amplified photoluminescence through large-area perovskite-based metasurfaces. ACS Nano 17, 2399–2410, https://doi.org/10.1021/acsnano.2c09482 (2023).

Weaver, J. H., Lynch, D. W. & Olson, C. G. Optical properties of niobium from 0.1 to 36.4 eV. Physical Review B 7, 4311–4318, https://doi.org/10.1103/physrevb.7.4311 (1973).

Harasaki, A. & Kato, K. New data on the nonlinear optical constant, phase-matching, and optical damage of AgGaS2. Japanese Journal of Applied Physics 36, 700, https://doi.org/10.1143/jjap.36.700 (1997).

Horcholle, B. et al. Growth and study of Tb3+ doped Nb2O5 thin films by radiofrequency magnetron sputtering: Photoluminescence properties. Applied Surface Science 597, 153711, https://doi.org/10.1016/j.apsusc.2022.153711 (2022).

Aspnes, D. E. & Studna, A. A. Dielectric functions and optical parameters of Si, Ge, GaP, GaAs, GaSb, InP, InAs, and InSb from 1.5 to 6.0 eV. Physical Review B 27, 985–1009, https://doi.org/10.1103/physrevb.27.985 (1983).

Radhakrishnan, T. Further studies on the temperature variation of the refractive index of crystals. Proceedings of the Indian Academy of Sciences - Section A 33, https://doi.org/10.1007/bf03172255 (1951).

Furthermore, users have the option to access the database through the RefractiveIndex.INFO website (https://refractiveindex.info). This online platform facilitates the browsing of data records and computations of various optical properties linked with n and k constants, such as Abbe numbers, reflectance, and Brewster’s angle.

Frisenda, R. et al. Characterization of highly crystalline lead iodide nanosheets prepared by room-temperature solution processing. Nanotechnology 28, 455703, https://doi.org/10.1088/1361-6528/aa8e5c (2017).

Kato, K. et al. Phase-matching properties of LiGaS2 in the 1.025–10.5910 μm spectral range. Optics Letters 42, 4363, https://doi.org/10.1364/ol.42.004363 (2017).

It’s important to note that users can create alternative ‘catalog’ files tailored to their specific needs. For instance, a customized catalog can contain only a subset of the dataset that is relevant for a particular application or study.

Jellison, G. E. et al. Refractive index of sodium iodide. Journal of Applied Physics 111, https://doi.org/10.1063/1.3689746 (2012).

Fujii, Y. & Sakudo, T. Dielectric and optical properties of KTaO3. Journal of the Physical Society of Japan 41, 888–893, https://doi.org/10.1143/jpsj.41.888 (1976).

Ordal, M. A., Bell, R. J., Alexander, R. W., Long, L. L. & Querry, M. R. Optical properties of Au, Ni, and Pb at submillimeter wavelengths. Applied Optics 26, 744, https://doi.org/10.1364/ao.26.000744 (1987).

Tatian, B. Fitting refractive-index data with the Sellmeier dispersion formula. Applied Optics 23, 4477, https://doi.org/10.1364/ao.23.004477 (1984).

Barker, A. S. & Ilegems, M. Infrared lattice vibrations and free-electron dispersion in GaN. Physical Review B 7, 743–750, https://doi.org/10.1103/physrevb.7.743 (1973).

Börzsönyi, A., Heiner, Z., Kalashnikov, M. P., Kovács, A. P. & Osvay, K. Dispersion measurement of inert gases and gas mixtures at 800 nm. Applied Optics 47, 4856, https://doi.org/10.1364/ao.47.004856 (2008).

Wang, K. et al. Order-of-magnitude multiphoton signal enhancement based on characterization of absorption spectra of immersion oils at the 1700-nm window. Optics Express 25, 5909, https://doi.org/10.1364/oe.25.005909 (2017).

Wood, D. L. & Nassau, K. Refractive index of cubic zirconia stabilized with yttria. Applied Optics 21, 2978, https://doi.org/10.1364/ao.21.002978 (1982).

Warren, S. G. & Brandt, R. E. Optical constants of ice from the ultraviolet to the microwave: A revised compilation. Journal of Geophysical Research: Atmospheres 113, https://doi.org/10.1029/2007jd009744 (2008).

Smith, D. R. & Loewenstein, E. V. Optical constants of far infrared materials 3: plastics. Applied Optics 14, 1335, https://doi.org/10.1364/ao.14.001335 (1975).

Join the ranks of world-leading microscopists with our expert training courses. Whether you're in academia or industry, a biologist, materials scientist, or somewhere in between, our training courses will help you unlock the full potential of your microscopy skills.

Parsons, D. F. & Coleman, P. D. Far infrared optical constants of gallium phosphide. Applied Optics 10, 1683, https://doi.org/10.1364/ao.10.1683_1 (1971).

The refractiveindex.info database emerged in response, offering a systematically organized, dynamic repository of optical constants. Since its inception in 2008, continuous enhancements have established it as a reliable resource, with the YAML-based file format ensuring data integrity and ease of access. The integration of the n2 database in 2023 reaffirms our dedication to addressing modern challenges in optics and photonics.

Kedenburg, S., Vieweg, M., Gissibl, T. & Giessen, H. Linear refractive index and absorption measurements of nonlinear optical liquids in the visible and near-infrared spectral region. Optical Materials Express 2, 1588, https://doi.org/10.1364/ome.2.001588 (2012).

θ is the objective’s angular aperture and n is the refractive index of the medium (air, water, or oil) between the objective and the specimen.

Gupta, V. et al. Mechanotunable surface lattice resonances in the visible optical range by soft lithography templates and directed self-assembly. ACS Applied Materials & Interfaces 11, 28189–28196, https://doi.org/10.1021/acsami.9b08871 (2019).

Kim, Y. D. et al. Optical properties of zinc-blende CdSe and ZnxCd1-xSe films grown on GaAs. Physical Review B 49, 7262–7270, https://doi.org/10.1103/physrevb.49.7262 (1994).

Zahedpour, S., Wahlstrand, J. K. & Milchberg, H. M. Measurement of the nonlinear refractive index of air constituents at mid-infrared wavelengths. Optics Letters 40, 5794, https://doi.org/10.1364/ol.40.005794 (2015).

The data records employ YAML-based file format (https://yaml.org), ensuring the data is both easily readable and maintainable. Each YAML file encompasses data related to a specific material, evaluated under defined conditions and reported in a particular publication, with a primary focus on the refractive index and extinction coefficient.

Philipp, H. R. Optical properties of silicon nitride. Journal of The Electrochemical Society 120, 295, https://doi.org/10.1149/1.2403440 (1973).

Shunji Ozaki, S. O. & Sadao Adachi, S. A. Optical constants of cubic ZnS. Japanese Journal of Applied Physics 32, 5008, https://doi.org/10.1143/jjap.32.5008 (1993).

Singh, S., Potopowicz, J. R., Van Uitert, L. G. & Wemple, S. H. Nonlinear optical properties of hexagonal silicon carbide. Applied Physics Letters 19, 53–56, https://doi.org/10.1063/1.1653819 (1971).

Li, H. H. Refractive index of ZnS, ZnSe, and ZnTe and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data 13, 103–150, https://doi.org/10.1063/1.555705 (1984).

Fernández-Perea, M. et al. Optical constants of Yb films in the 23–1700 eV range. Journal of the Optical Society of America A 24, 3691, https://doi.org/10.1364/josaa.24.003691 (2007).

White, W. T., Smith, W. L. & Milam, D. Direct measurement of the nonlinear refractive-index coefficient γ at 355 nm in fused silica and in BK-10 glass. Optics Letters 9, 10, https://doi.org/10.1364/ol.9.000010 (1984).

Fernández-Perea, M. et al. Transmittance and optical constants of Ho films in the 3–1340 eV spectral range. Journal of Applied Physics 109, https://doi.org/10.1063/1.3556451 (2011).

Fischer, M. P. et al. Coherent field transients below 15 THz from phase-matched difference frequency generation in 4H-SiC. Optics Letters 42, 2687, https://doi.org/10.1364/ol.42.002687 (2017).

Djurišić, A. B. & Li, E. H. Optical properties of graphite. Journal of Applied Physics 85, 7404–7410, https://doi.org/10.1063/1.369370 (1999).

Caldwell, R. S. & Fan, H. Y. Optical properties of tellurium and selenium. Physical Review 114, 664–675, https://doi.org/10.1103/physrev.114.664 (1959).

Brimhall, N. et al. Measured optical constants of copper from 10 nm to 35 nm. Optics Express 17, 23873, https://doi.org/10.1364/oe.17.023873 (2009).

Dodge, M. J. Refractive properties of magnesium fluoride. Applied Optics 23, 1980, https://doi.org/10.1364/ao.23.001980 (1984).

Yao, C., Shen, W., Hu, X. & Hu, C. Optical properties of large-size and damage-free polished Lu2O3 single crystal covering the ultraviolet-visible-and near-infrared (UV–VIS–NIR) spectral region. Journal of Alloys and Compounds 897, 162726, https://doi.org/10.1016/j.jallcom.2021.162726 (2022).

Munkhbat, B., Wróbel, P., Antosiewicz, T. J. & Shegai, T. O. Optical constants of several multilayer transition metal dichalcogenides measured by spectroscopic ellipsometry in the 300–1700 nm range: High index, anisotropy, and hyperbolicity. ACS Photonics 9, 2398–2407, https://doi.org/10.1021/acsphotonics.2c00433 (2022).

Johnson, P. & Christy, R. Optical constants of transition metals: Ti, V, Cr, Mn, Fe, Co, Ni, and Pd. Physical Review B 9, 5056–5070, https://doi.org/10.1103/physrevb.9.5056 (1974).

McPeak, K. M. et al. Plasmonic films can easily be better: Rules and recipes. ACS Photonics 2, 326–333, https://doi.org/10.1021/ph5004237 (2015).

As an illustrative example, consider a data record for SiO2 in which the refractive index n is expressed through a dispersion formula. The associated YAML file is located at data-nk/main/SiO2/Malitson.yml and is organized as follows:

Numericalapertureand resolution

Johnson, P. B. & Christy, R. W. Optical constants of the noble metals. Physical Review B 6, 4370–4379, https://doi.org/10.1103/physrevb.6.4370 (1972).

Nunley, T. N. et al. Optical constants of germanium and thermally grown germanium dioxide from 0.5 to 6.6 eV via a multisample ellipsometry investigation. Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena 34, https://doi.org/10.1116/1.4963075 (2016).

Sani, E. & Dell’Oro, A. Spectral optical constants of ethanol and isopropanol from ultraviolet to far infrared. Optical Materials 60, 137–141, https://doi.org/10.1016/j.optmat.2016.06.041 (2016).

Malitson, I. H. Refraction and dispersion of synthetic sapphire. Journal of the Optical Society of America 52, 1377, https://doi.org/10.1364/josa.52.001377 (1962).

Bideau-Mehu, A., Guern, Y., Abjean, R. & Johannin-Gilles, A. Interferometric determination of the refractive index of carbon dioxide in the ultraviolet region. Optics Communications 9, 432–434, https://doi.org/10.1016/0030-4018(73)90289-7 (1973).

Guo, Z., Gu, H., Yu, Y., Wei, Z. & Liu, S. Broadband and incident-angle-modulation near-infrared polarizers based on optically anisotropic SnSe. Nanomaterials 13, 134, https://doi.org/10.3390/nano13010134 (2022).

Phillips, L. J. et al. Dispersion relation data for methylammonium lead triiodide perovskite deposited on a (100) silicon wafer using a two-step vapour-phase reaction process. Data in Brief 5, 926–928, https://doi.org/10.1016/j.dib.2015.10.026 (2015).

Green, M. A. & Keevers, M. J. Optical properties of intrinsic silicon at 300 K. Progress in Photovoltaics: Research and Applications 3, 189–192, https://doi.org/10.1002/pip.4670030303 (1995).

Vogt, M. R. et al. Optical constants of UV transparent EVA and the impact on the PV module output power under realistic irradiation. Energy Procedia 92, 523–530, https://doi.org/10.1016/j.egypro.2016.07.136 (2016).

Hrabovský, J., Kučera, M., Paloušová, L., Bi, L. & Veis, M. Optical characterization of Y3Al5O12 and Lu3Al5O12 single crystals. Optical Materials Express 11, 1218, https://doi.org/10.1364/ome.417670 (2021).

Jöbsis, H. J. et al. Recombination and localization: Unfolding the pathways behind conductivity losses in Cs2AgBiBr6 thin films. Applied Physics Letters 119, https://doi.org/10.1063/5.0061899 (2021).

Sutherland, J. C. & Arakawa, E. T. Optical properties of potassium for photons of energy 396 to 969 eV. Journal of the Optical Society of America 58, 1080, https://doi.org/10.1364/josa.58.001080 (1968).

Whang, U. S., Arakawa, E. T. & Callcott, T. A. Optical properties of K between 4 and 10.7 eV and comparison with Na, Rb, and Cs. Physical Review B 6, 2109–2118, https://doi.org/10.1103/physrevb.6.2109 (1972).

Chengchao, W., Xingcan, L., Jianyu, T. & Linhua, L. Experimental measurement of optical constant of biodiesel by double optical pathlength transmission method. Laser & Optoelectronics Progress 52, 051206, https://doi.org/10.3788/lop52.051206 (2015).

Glass makers’ catalogs: We checked the websites of glass manufacturers for catalogs of glasses they produce. These catalogs are often available in Zemax AGF format, suitable for automatic data extraction.

Smith, N. V. Optical constants of sodium and potassium from 0.5 to 4.0 eV by split-beam ellipsometry. Physical Review 183, 634–644, https://doi.org/10.1103/physrev.183.634 (1969).

Smith, F. W. Optical constants of a hydrogenated amorphous carbon film. Journal of Applied Physics 55, 764–771, https://doi.org/10.1063/1.333135 (1984).

Jellison, G. Optical functions of silicon determined by two-channel polarization modulation ellipsometry. Optical Materials 1, 41–47, https://doi.org/10.1016/0925-3467(92)90015-f (1992).

König, T. A. F. et al. Electrically tunable plasmonic behavior of nanocube–polymer nanomaterials induced by a redox-active electrochromic polymer. ACS Nano 8, 6182–6192, https://doi.org/10.1021/nn501601e (2014).

Numericalapertureformula with refractive index

Bååk, T. Silicon oxynitride; a material for GRIN optics. Applied Optics 21, 1069, https://doi.org/10.1364/ao.21.001069 (1982).

Sahin, S., Nahar, N. K. & Sertel, K. Dielectric properties of low-loss polymers for mmw and THz applications. Journal of Infrared, Millimeter, and Terahertz Waves 40, 557–573, https://doi.org/10.1007/s10762-019-00584-2 (2019).

Manual number-by-number comparison: This test is routinely performed when the data is represented by a relatively small amount of numerical values, e.g., coefficients of a dispersion formula.

Resolution is clearly influenced by the objective’s numerical aperture. Note that lower values of D indicate higher resolution. In the tutorial, the Numerical Aperture slider is used to control how the image structure evolves as the objective’s numerical aperture is increased. At the lowest numerical aperture value (0.20), the image details visible in the microscope are poorly defined and surrounded by diffraction fringes. As the slider is moved to higher numerical aperture values (0.50-0.80), the structural outline of the image becomes sharper and higher-order diffraction rings begin to emerge. At the highest numerical apertures (1.00-1.30), the diffraction disks are resolved individually as discrete luminous points surrounded by alternating series of bright and dark higher-order diffraction rings of decreasing intensity.

Papatryfonos, K. et al. Refractive indices of mbe-grown AlxGa(1-x)As ternary alloys in the transparent wavelength region. AIP Advances 11, https://doi.org/10.1063/5.0039631 (2021).

Stefaniuk, T. et al. Optical, electronic, and structural properties of ScAlMgO4. Physical Review B 107, https://doi.org/10.1103/physrevb.107.085205 (2023).

Debenham, M. Refractive indices of zinc sulfide in the 0.405–13-μm wavelength range. Applied Optics 23, 2238, https://doi.org/10.1364/ao.23.002238 (1984).

Ciddor, P. E. Refractive index of air: new equations for the visible and near infrared. Applied Optics 35, 1566, https://doi.org/10.1364/ao.35.001566 (1996).

Daimon, M. & Masumura, A. High-accuracy measurements of the refractive index and its temperature coefficient of calcium fluoride in a wide wavelength range from 138 to 2326 nm. Applied Optics 41, 5275, https://doi.org/10.1364/ao.41.005275 (2002).

Medenbach, O., Dettmar, D., Shannon, R. D., Fischer, R. X. & Yen, W. M. Refractive index and optical dispersion of rare earth oxides using a small-prism technique. Journal of Optics A: Pure and Applied Optics 3, 174–177, https://doi.org/10.1088/1464-4258/3/3/303 (2001).

Chemnitz, M. et al. Hybrid soliton dynamics in liquid-core fibres. Nature Communications 8, https://doi.org/10.1038/s41467-017-00033-5 (2017).

Lomheim, T. S. & DeShazer, L. G. Optical-absorption intensities of trivalent neodymium in the uniaxial crystal yttrium orthovanadate. Journal of Applied Physics 49, 5517–5522, https://doi.org/10.1063/1.324471 (1978).

Taylor, A. et al. Comparative determination of atomic boron and carrier concentration in highly boron doped nano-crystalline diamond. Diamond and Related Materials 135, 109837, https://doi.org/10.1016/j.diamond.2023.109837 (2023).

Callcott, T. A. & Arakawa, E. T. Ultraviolet optical properties of Li. Journal of the Optical Society of America 64, 839, https://doi.org/10.1364/josa.64.000839 (1974).

Kerl, K. & Varchmin, H. Refractive index dispersion (RID) of some liquids in the UV/VIS between 20 °C and 60 °C. Journal of Molecular Structure 349, 257–260, https://doi.org/10.1016/0022-2860(95)08758-n (1995).

DeSalvo, R., Said, A., Hagan, D., Van Stryland, E. & Sheik-Bahae, M. Infrared to ultraviolet measurements of two-photon absorption and n2 in wide bandgap solids. IEEE Journal of Quantum Electronics 32, 1324–1333, https://doi.org/10.1109/3.511545 (1996).

Accurately determining both n and k, and their chromatic dispersion, is crucial in science, engineering, and 3D artistic rendering. The intricate design of optical instruments, particularly those minimizing aberrations, depends heavily on understanding the n(λ) function of transparent optical materials2. Cross-disciplinary efforts to characterize optical material properties have resulted in a wealth of datasets and analytical formulas, enhancing our grasp and utilization of optical constants.

Iezzi, B. et al. Electrohydrodynamic jet printing of 1D photonic crystals: Part II–optical design and reflectance characteristics. Advanced Materials Technologies 5, https://doi.org/10.1002/admt.202000431 (2020).

The code that underpins the refractiveindex.info database is made accessible under the Creative Commons Zero (CC0) license (https://creativecommons.org/publicdomain/zero/1.0). This license facilitates the unrestricted use, distribution, and modification of the code, making it widely accessible for various applications. The entire codebase, including detailed documentation, is publicly available on the refractiveindex.info-database GitHub project (https://github.com/polyanskiy/refractiveindex.info-database). This repository is regularly updated, ensuring it evolves to meet the ongoing needs of both the scientific and engineering sectors. For additional utility, users can explore the refractiveindex.info-scripts project on GitHub (https://github.com/polyanskiy/refractiveindex.info-scripts), which offers scripts for deriving optical constants from established models and tools for converting Zemax glass catalogs to the dataset’s YAML format.

Adachi, S., Kimura, T. & Suzuki, N. Optical properties of CdTe: Experiment and modeling. Journal of Applied Physics 74, 3435–3441, https://doi.org/10.1063/1.354543 (1993).

Zhang, J., Lu, Z. H. & Wang, L. J. Precision refractive index measurements of air, N2, O2, Ar, and CO2 with a frequency comb. Applied Optics 47, 3143, https://doi.org/10.1364/ao.47.003143 (2008).

Werner, K. et al. Ultrafast mid-infrared high harmonic and supercontinuum generation with n2 characterization in zinc selenide. Optics Express 27, 2867, https://doi.org/10.1364/oe.27.002867 (2019).

Stahrenberg, K. et al. Optical properties of copper and silver in the energy range 2.5–9.0 eV. Physical Review B 64, https://doi.org/10.1103/physrevb.64.115111 (2001).

Skauli, T. et al. Improved dispersion relations for gaas and applications to nonlinear optics. Journal of Applied Physics 94, 6447–6455, https://doi.org/10.1063/1.1621740 (2003).

Loiko, P. et al. Sellmeier equations, group velocity dispersion, and thermo-optic dispersion formulas for CaLnAlO4 (Ln = Y, Gd) laser host crystals. Optics Letters 42, 2275, https://doi.org/10.1364/ol.42.002275 (2017).

Rodney, W. S. & Malitson, I. H. Refraction and dispersion of thallium bromide iodide. Journal of the Optical Society of America 46, 956, https://doi.org/10.1364/josa.46.000956 (1956).

Joseph, S., Sarkar, S., Khan, S. & Joseph, J. Exploring the optical bound state in the continuum in a dielectric grating coupled plasmonic hybrid system. Advanced Optical Materials 9, https://doi.org/10.1002/adom.202001895 (2021).

Chandler-Horowitz, D. & Amirtharaj, P. M. High-accuracy, midinfrared (450 cm−1 ≤ ω ≤ 4000 cm−1) refractive index values of silicon. Journal of Applied Physics 97, https://doi.org/10.1063/1.1923612 (2005).

Milam, D. Review and assessment of measured values of the nonlinear refractive-index coefficient of fused silica. Applied Optics 37, 546, https://doi.org/10.1364/ao.37.000546 (1998).

Bucciarelli, A. et al. A comparative study of the refractive index of silk protein thin films towards biomaterial based optical devices. Optical Materials 78, 407–414, https://doi.org/10.1016/j.optmat.2018.02.058 (2018).

Song, B. et al. Layer-dependent dielectric function of wafer-scale 2D MoS2. Advanced Optical Materials 7, https://doi.org/10.1002/adom.201801250 (2018).

Li, H. H. Refractive index of alkali halides and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data 5, 329–528, https://doi.org/10.1063/1.555536 (1976).

Shimoji, Y., Fay, A. T., Chang, R. S. F. & Djeu, N. Direct measurement of the nonlinear refractive index of air. Journal of the Optical Society of America B 6, 1994, https://doi.org/10.1364/josab.6.001994 (1989).

Peck, E. R. & Fisher, D. J. Dispersion of argon. Journal of the Optical Society of America 54, 1362, https://doi.org/10.1364/josa.54.001362 (1964).

Belosludtsev, A. et al. Correlation between stoichiometry and properties of scandium oxide films prepared by reactive magnetron sputtering. Applied Surface Science 427, 312–318, https://doi.org/10.1016/j.apsusc.2017.08.068 (2018).

Larruquert, J. I. et al. Optical properties of scandium films in the far and the extreme ultraviolet. Applied Optics 43, 3271, https://doi.org/10.1364/ao.43.003271 (2004).

Supansomboon, S., Maaroof, A. & Cortie, M. B. “purple glory”: The optical properties and technology of AuAl2 coatings. Gold Bulletin 41, 296–304, https://doi.org/10.1007/bf03214887 (2008).

It is pivotal to underscore that our work does not generate original experimental data. Instead, we create a comprehensive data repository, systematizing and cataloging existing optical constants published by others. This approach ensures a diverse and rich collection of verified data is readily accessible for various applications in a standardized format. As a result, this section does not describe experimental procedures but focuses on the methodologies employed in data collection and formatting.

Zernike, F. Refractive indices of ammonium dihydrogen phosphate and potassium dihydrogen phosphate between 2000 Å and 15 μ. Journal of the Optical Society of America 54, 1215, https://doi.org/10.1364/josa.54.001215 (1964).

Larsén, T. Beitrag zur dispersion der edelgase. Zeitschrift für Physik 88, 389–394, https://doi.org/10.1007/bf01343498 (1934).

Chen, C. et al. New nonlinear-optical crystal: LiB3O5. Journal of the Optical Society of America B 6, 616, https://doi.org/10.1364/josab.6.000616 (1989).

This foundational knowledge article explores the effects of the numerical aperture (NA) of an objective lens on the resolution of images produced by a microscope. It explains the diffraction pattern produced by an objective lens and how increasing the NA results in higher resolution images. The tutorial demonstrates the changes in image structure as the NA is adjusted.

Ives, H. E. & Briggs, H. B. The optical constants of potassium. Journal of the Optical Society of America 26, 238, https://doi.org/10.1364/josa.26.000238 (1936).

Schneider, F., Draheim, J., Kamberger, R. & Wallrabe, U. Process and material properties of polydimethylsiloxane (PDMS) for optical MEMS. Sensors and Actuators A: Physical 151, 95–99, https://doi.org/10.1016/j.sna.2009.01.026 (2009).

Monin, J. & Boutry, G. A. Optical and photoelectric properties of alkali metals. Physical Review B 9, 1309–1327, https://doi.org/10.1103/physrevb.9.1309 (1974).

Here, the first column corresponds to the wavelength in micrometers, while the others represent the unitless refractive index n and extinction coefficient k. Alternatively, n and k can be outlined separately in two two-column entries. A data entry might also combine a dispersion formula for n with numerical data for k, as illustrated in the SCHOTT N-BK7 glass dataset at data-nk/glass/schott/N-BK7.yml:

Weber, J. W., Calado, V. E. & van de Sanden, M. C. M. Optical constants of graphene measured by spectroscopic ellipsometry. Applied Physics Letters 97, https://doi.org/10.1063/1.3475393 (2010).

Tikuišis, K. K. et al. Optical and magneto-optical properties of permalloy thin films in 0.7–6.4 eV photon energy range. Materials & Design 114, 31–39, https://doi.org/10.1016/j.matdes.2016.10.036 (2017).

Ives, H. E. & Briggs, H. B. Optical constants of rubidium and cesium. Journal of the Optical Society of America 27, 395, https://doi.org/10.1364/josa.27.000395 (1937).

Ninomiya, S. & Adachi, S. Optical properties of wurtzite CdS. Journal of Applied Physics 78, 1183–1190, https://doi.org/10.1063/1.360355 (1995).

Since the described dataset5 represents an extensive array of data compiled by the work of thousands of researchers over more than a century, we cannot verify the accuracy of every individual record. Instead, we rely on the peer-review process employed by publishers of scientific and technical journals, and on the experience and reputation of optical material manufacturers publishing their material properties. However, we make every effort to ensure the correctness of the data extraction and conversion process, as well as the consistency of the information included in the dataset. In particular, the following steps are typically involved in the process of adding a new data record.

Loiko, P. & Major, A. Dispersive properties of alexandrite and beryllium hexaaluminate crystals. Optical Materials Express 6, 2177, https://doi.org/10.1364/ome.6.002177 (2016).

Bertie, J. E., Lan, Z., Jones, R. N. & Apelblat, Y. Infrared intensities of liquids XVIII: Accurate optical constants and molar absorption coefficients between 6500 and 800 cm−1 of dichloromethane at 25 °C, from spectra recorded in several laboratories. Applied Spectroscopy 49, 840–851, https://doi.org/10.1366/0003702953964435 (1995).

Hale, G. M. & Querry, M. R. Optical constants of water in the 200-nm to 200-μm wavelength region. Applied Optics 12, 555, https://doi.org/10.1364/ao.12.000555 (1973).

Rioux, D. et al. An analytic model for the dielectric function of Au, Ag, and their alloys. Advanced Optical Materials 2, 176–182, https://doi.org/10.1002/adom.201300457 (2013).

Rasigni, M. & Rasigni, G. Optical constants of lithium deposits as determined from the Kramers-Kronig analysis. Journal of the Optical Society of America 67, 54, https://doi.org/10.1364/josa.67.000054 (1977).

Bright, T., Watjen, J., Zhang, Z., Muratore, C. & Voevodin, A. Optical properties of HfO2 thin films deposited by magnetron sputtering: From the visible to the far-infrared. Thin Solid Films 520, 6793–6802, https://doi.org/10.1016/j.tsf.2012.07.037 (2012).

Kato, K., Miyata, K., Badikov, V. V. & Petrov, V. Phase-matching properties of BaGa2GeSe6 for three-wave interactions in the 0.778–10.5910 μm spectral range. Applied Optics 57, 7440, https://doi.org/10.1364/ao.57.007440 (2018).

Gao, L., Lemarchand, F. & Lequime, M. Refractive index determination of SiO2 layer in the UV/Vis/NIR range: spectrophotometric reverse engineering on single and bi-layer designs. Journal of the European Optical Society: Rapid Publications 8, https://doi.org/10.2971/jeos.2013.13010 (2013).

Mavrona, E. et al. Refractive index measurement of IP-S and IP-Dip photoresists at THz frequencies and validation via 3D photonic metamaterials made by direct laser writing. Optical Materials Express 13, 3355, https://doi.org/10.1364/ome.500287 (2023).

Smith, N. V. Optical constants of rubidium and cesium from 0.5 to 4.0 eV. Physical Review B 2, 2840–2848, https://doi.org/10.1103/physrevb.2.2840 (1970).

Ermolaev, G. A. et al. Broadband optical properties of atomically thin PtS2 and PtSe2. Nanomaterials 11, 3269, https://doi.org/10.3390/nano11123269 (2021).

Data on the optical properties of materials is aggregated from a variety of publicly accessible and credible sources, ensuring a wide range of optical constants is represented. The systematic collection process involves categorizing the data based on the type of material, its properties, and the source of information. The entire process is mostly manual due to the large variety of data sources and presentation methods. Below, we detail the steps typically undertaken to identify sources, extract data, and convert it into a unified format used in the data records.

Babar, S. & Weaver, J. H. Optical constants of cu, ag, and au revisited. Applied Optics 54, 477, https://doi.org/10.1364/ao.54.000477 (2015).

Larruquert, J. I. et al. Self-consistent optical constants of sputter-deposited B4C thin films. Journal of the Optical Society of America A 29, 117, https://doi.org/10.1364/josaa.29.000117 (2011).

Cross-entry comparison: Plotting data entries for the same material from different sources on the same plot may help reveal a systematic error in a particular data record if a corresponding curve deviates from a general trend. An example of a Python-based user interface allowing for easy data comparison is given in the following section.

Tilton, L. W., Plyler, E. K. & Stephens, R. E. Refractive index of silver chloride for visible and infra-red radiant energy. Journal of the Optical Society of America 40, 540, https://doi.org/10.1364/josa.40.000540 (1950).

Kaminskii, A. A. et al. Mechanical and optical properties of Lu2O3 host-ceramics for Ln3+ lasants. Laser Physics Letters 5, 300–303, https://doi.org/10.1002/lapl.200710128 (2007).

Guo, Z., Gu, H., Fang, M., Ye, L. & Liu, S. Giant in-plane optical and electronic anisotropy of tellurene: a quantitative exploration. Nanoscale 14, 12238–12246, https://doi.org/10.1039/d2nr03226k (2022).

Sheik-Bahae, M., Hutchings, D., Hagan, D. & Van Stryland, E. Dispersion of bound electron nonlinear refraction in solids. IEEE Journal of Quantum Electronics 27, 1296–1309, https://doi.org/10.1109/3.89946 (1991).

Marcos, L. R.-d et al. Transmittance and optical constants of Ca films in the 4–1000 eV spectral range. Applied Optics 54, 1910, https://doi.org/10.1364/ao.54.001910 (2015).

Inagaki, T., Emerson, L. C., Arakawa, E. T. & Williams, M. W. Optical properties of solid Na and Li between 0.6 and 3.8 eV. Physical Review B 13, 2305–2313, https://doi.org/10.1103/physrevb.13.2305 (1976).

Choy, M. M. & Byer, R. L. Accurate second-order susceptibility measurements of visible and infrared nonlinear crystals. Physical Review B 14, 1693–1706, https://doi.org/10.1103/physrevb.14.1693 (1976).

Ordal, M. A., Bell, R. J., Alexander, R. W., Newquist, L. A. & Querry, M. R. Optical properties of Al, Fe, Ti, Ta, W, and Mo at submillimeter wavelengths. Applied Optics 27, 1203, https://doi.org/10.1364/ao.27.001203 (1988).

Larruquert, J. I., Aznárez, J. A., Méndez, J. A. & Calvo-Angós, J. Optical properties of ytterbium films in the far and the extreme ultraviolet. Applied Optics 42, 4566, https://doi.org/10.1364/ao.42.004566 (2003).

Zelmon, D. E., Hanning, E. A. & Schunemann, P. G. Refractive-index measurements and Sellmeier coefficients for zinc germanium phosphide from 2 to 9 μm with implications for phase matching in optical frequency-conversion devices. Journal of the Optical Society of America B 18, 1307, https://doi.org/10.1364/josab.18.001307 (2001).

Edwards, D. F. & Ochoa, E. Infrared refractive index of silicon. Applied Optics 19, 4130, https://doi.org/10.1364/ao.19.004130 (1980).

Kato, K. High-power difference-frequency generation at 4.4–5.7 μm in LiIO3. IEEE Journal of Quantum Electronics 21, 119–120, https://doi.org/10.1109/jqe.1985.1072617 (1985).

Cuthbertson, C. & Cuthbertson, M. On the refraction and dispersion of the halogens, halogen acids, ozone, steam, oxides of nitrogen and ammonia. Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character 213, 1–26, https://doi.org/10.1098/rsta.1914.0001 (1914).

Leite, T. R., Zschiedrich, L., Kizilkaya, O. & McPeak, K. M. Resonant plasmonic–biomolecular chiral interactions in the far-ultraviolet: Enantiomeric discrimination of sub-10 nm amino acid films. Nano Letters 22, 7343–7350, https://doi.org/10.1021/acs.nanolett.2c01724 (2022).

Fernández-Perea, M. et al. Transmittance and optical constants of Eu films from 8.3 to 1400 eV. Journal of Applied Physics 104, https://doi.org/10.1063/1.2982391 (2008).

Kato, K. & Takaoka, E. Sellmeier and thermo-optic dispersion formulas for KTP. Applied Optics 41, 5040, https://doi.org/10.1364/ao.41.005040 (2002).

Search engines: We perform a broader search for publications on optical properties of materials using tools like Google Scholar to find newer references and those that may have been missed in earlier steps.

Geints, Y. E. et al. Kerr-driven nonlinear refractive index of air at 800 and 400 nm measured through femtosecond laser pulse filamentation. Applied Physics Letters 99, https://doi.org/10.1063/1.3657774 (2011).

Bliss, E. S., Speck, D. R. & Simmons, W. W. Direct interferometric measurements of the nonlinear refractive index coefficient n2 in laser materials. Applied Physics Letters 25, 728–730, https://doi.org/10.1063/1.1655378 (1974).

Gan, F. Optical properties of fluoride glasses: a review. Journal of Non-Crystalline Solids 184, 9–20, https://doi.org/10.1016/0022-3093(94)00592-3 (1995).

DeVore, J. R. Refractive indices of rutile and sphalerite. Journal of the Optical Society of America 41, 416, https://doi.org/10.1364/josa.41.000416 (1951).

Shkondin, E., Repän, T., Takayama, O. & Lavrinenko, A. V. High aspect ratio titanium nitride trench structures as plasmonic biosensor. Optical Materials Express 7, 4171, https://doi.org/10.1364/ome.7.004171 (2017).

Bond, W. L., Boyd, G. D. & Carter, H. L. Refractive indices of HgS (cinnabar) between 0.62 and 11 μ. Journal of Applied Physics 38, 4090–4091, https://doi.org/10.1063/1.1709079 (1967).

Kitamura, R., Pilon, L. & Jonasz, M. Optical constants of silica glass from extreme ultraviolet to far infrared at near room temperature. Applied Optics 46, 8118, https://doi.org/10.1364/ao.46.008118 (2007).

Warren, S. G. Optical constants of ice from the ultraviolet to the microwave. Applied Optics 23, 1206, https://doi.org/10.1364/ao.23.001206 (1984).

Pigeon, J. J., Matteo, D. A., Tochitsky, S. Y., Ben-Zvi, I. & Joshi, C. Measurements of the nonlinear refractive index of AgGaSe2, GaSe, and ZnSe at 10 μm. Journal of the Optical Society of America B 37, 2076, https://doi.org/10.1364/josab.395844 (2020).

Larruquert, J. I. et al. Transmittance and optical constants of erbium films in the 325–1580 eV spectral range. Applied Optics 50, 2211, https://doi.org/10.1364/ao.50.002211 (2011).

Peck, E. R. & Reeder, K. Dispersion of air. Journal of the Optical Society of America 62, 958, https://doi.org/10.1364/josa.62.000958 (1972).

Šik, J., Hora, J. & Humlíček, J. Optical functions of silicon at high temperatures. Journal of Applied Physics 84, 6291–6298, https://doi.org/10.1063/1.368951 (1998).

Peter, F. Über brechungsindizes und absorptionskonstanten des diamanten zwischen 644 und 226 mμ. Zeitschrift für Physik 15, 358–368, https://doi.org/10.1007/bf01330487 (1923).

A variety of third-party scripts and web applications that harness the refractiveindex.info dataset can be found, notably on GitHub. These tools offer users alternative avenues to efficiently access and employ the data.

Kato, K., Miyata, K. & Petrov, V. Refined Sellmeier equations for AgGaSe2 up to 18 μm. Applied Optics 60, 805, https://doi.org/10.1364/ao.401828 (2021).

Patwardhan, G. N., Ginsberg, J. S., Chen, C. Y., Jadidi, M. M. & Gaeta, A. L. Nonlinear refractive index of solids in mid-infrared. Optics Letters 46, 1824, https://doi.org/10.1364/ol.421469 (2021).

Brannon, J. H., Lankard, J. R., Baise, A. I., Burns, F. & Kaufman, J. Excimer laser etching of polyimide. Journal of Applied Physics 58, 2036–2043, https://doi.org/10.1063/1.336012 (1985).

Kofman, V., He, J., Loes ten Kate, I. & Linnartz, H. The refractive index of amorphous and crystalline water ice in the UV–vis. The Astrophysical Journal 875, 131, https://doi.org/10.3847/1538-4357/ab0d89 (2019).

Beaini, R., Baloukas, B., Loquai, S., Klemberg-Sapieha, J. & Martinu, L. Thermochromic VO2-based smart radiator devices with ultralow refractive index cavities for increased performance. Solar Energy Materials and Solar Cells 205, 110260, https://doi.org/10.1016/j.solmat.2019.110260 (2020).

Tikuišis, K. K. et al. Dielectric function of epitaxial quasi-freestanding monolayer graphene on Si-face 6H-SiC in a broad spectral range. Physical Review Materials 7, https://doi.org/10.1103/physrevmaterials.7.044201 (2023).

Le, T. N., Pelouard, J.-L., Charra, F. & Vassant, S. Determination of the far-infrared dielectric function of a thin InGaAs layer using a detuned Salisbury screen. Optical Materials Express 12, 2711, https://doi.org/10.1364/ome.455445 (2022).

Stephens, R. & Malitson, I. Index of refraction of magnesium oxide. Journal of Research of the National Bureau of Standards 49, 249, https://doi.org/10.6028/jres.049.025 (1952).

Lorimor, O. G. & Spitzer, W. G. Infrared refractive index and absorption of InAs and CdTe. Journal of Applied Physics 36, 1841–1844, https://doi.org/10.1063/1.1714362 (1965).

Yamaguchi, S. & Hanyu, T. Optical properties of potassium. Journal of the Physical Society of Japan 31, 1431–1441, https://doi.org/10.1143/jpsj.31.1431 (1971).

Shaffer, P. T. B. Refractive index, dispersion, and birefringence of silicon carbide polytypes. Applied Optics 10, 1034, https://doi.org/10.1364/ao.10.001034 (1971).

Inagaki, T., Hamm, R. N., Arakawa, E. T. & Painter, L. R. Optical and dielectric properties of DNA in the extreme ultraviolet. The Journal of Chemical Physics 61, 4246–4250, https://doi.org/10.1063/1.1681724 (1974).

Laiho, R. & Lakkisto, M. Investigation of the refractive indices of LaF3, CeF3, PrF3 and NdF3. Philosophical Magazine B 48, 203–207, https://doi.org/10.1080/13642818308226470 (1983).

Bhar, G. C. Refractive index interpolation in phase-matching. Applied Optics 15, 305, https://doi.org/10.1364/ao.15.0305_1 (1976).

Tsuda, S., Yamaguchi, S., Kanamori, Y. & Yugami, H. Spectral and angular shaping of infrared radiation in a polymer resonator with molecular vibrational modes. Optics Express 26, 6899, https://doi.org/10.1364/oe.26.006899 (2018).

Hsu, C. et al. Thickness-dependent refractive index of 1L, 2L, and 3L MoS2, MoSe2, WS2, and WSe2. Advanced Optical Materials 7, https://doi.org/10.1002/adom.201900239 (2019).

Kabaciński, P., Kardaś, T. M., Stepanenko, Y. & Radzewicz, C. Nonlinear refractive index measurement by SPM-induced phase regression. Optics Express 27, 11018, https://doi.org/10.1364/oe.27.011018 (2019).

Windt, D. L. et al. Optical constants for thin films of Ti, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Ir, Os, Pt, and Au from 24 Å to 1216 Å. Applied Optics 27, 246, https://doi.org/10.1364/ao.27.000246 (1988).

By integrating a comprehensive data collection, adopting a standard-based data file format, ensuring ongoing updates, and maintaining open access, the refractiveindex.info emerges as an essential tool for researchers, engineers, and students delving into the complex world of optical constants and material properties.

Wang, Y. et al. Measurement of absorption spectrum of deuterium oxide (D2O) and its application to signal enhancement in multiphoton microscopy at the 1700-nm window. Applied Physics Letters 108, https://doi.org/10.1063/1.4939970 (2016).

Perotto, G. et al. The optical properties of regenerated silk fibroin films obtained from different sources. Applied Physics Letters 111, https://doi.org/10.1063/1.4998950 (2017).

Numericalapertureformula

Afsar, M. N. & Hasted, J. B. Measurements of the optical constants of liquid H2O and D2O between 6 and 450 cm−1. Journal of the Optical Society of America 67, 902, https://doi.org/10.1364/josa.67.000902 (1977).

Gao, L., Lemarchand, F. & Lequime, M. Exploitation of multiple incidences spectrometric measurements for thin film reverse engineering. Optics Express 20, 15734, https://doi.org/10.1364/oe.20.015734 (2012).

Li, H. H. Refractive index of alkaline earth halides and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data 9, 161–290, https://doi.org/10.1063/1.555616 (1980).

Boidin, R., Halenkovič, T., Nazabal, V., Beneš, L. & Němec, P. Pulsed laser deposited alumina thin films. Ceramics International 42, 1177–1182, https://doi.org/10.1016/j.ceramint.2015.09.048 (2016).

Cuthbertson, C. & Cuthbertson, M. The refraction and dispersion of neon and helium. Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character 135, 40–47, https://doi.org/10.1098/rspa.1932.0019 (1932).

Palm, K. J., Murray, J. B., Narayan, T. C. & Munday, J. N. Dynamic optical properties of metal hydrides. ACS Photonics 5, 4677–4686, https://doi.org/10.1021/acsphotonics.8b01243 (2018).

Sarkar, S. et al. Hybridized guided-mode resonances via colloidal plasmonic self-assembled grating. ACS Applied Materials & Interfaces 11, 13752–13760, https://doi.org/10.1021/acsami.8b20535 (2019).

Rodríguez-de Marcos, L. V., Larruquert, J. I., Méndez, J. A. & Aznárez, J. A. Self-consistent optical constants of SiO2 and Ta2O5 films. Optical Materials Express 6, 3622, https://doi.org/10.1364/ome.6.003622 (2016).

Hagemann, H.-J., Gudat, W. & Kunz, C. Optical constants from the far infrared to the x-ray region: Mg, Al, Cu, Ag, Au, Bi, C, and Al2O3. Journal of the Optical Society of America 65, 742, https://doi.org/10.1364/josa.65.000742 (1975).

Ermolaev, G. A. et al. Broadband optical constants and nonlinear properties of SnS2 and SnSe2. Nanomaterials 12, 141, https://doi.org/10.3390/nano12010141 (2021).

Gu, H. et al. Layer-dependent dielectric and optical properties of centimeter-scale 2D WSe2: evolution from a single layer to few layers. Nanoscale 11, 22762–22771, https://doi.org/10.1039/c9nr04270a (2019).

Fang, M. et al. Layer-dependent dielectric permittivity of topological insulator Bi2Se3 thin films. Applied Surface Science 509, 144822, https://doi.org/10.1016/j.apsusc.2019.144822 (2020).

Peck, E. R. & Huang, S. Refractivity and dispersion of hydrogen in the visible and near infrared. Journal of the Optical Society of America 67, 1550, https://doi.org/10.1364/josa.67.001550 (1977).

Uchida, N. Optical properties of single-crystal paratellurite (TeO2). Physical Review B 4, 3736–3745, https://doi.org/10.1103/physrevb.4.3736 (1971).

Kischkat, J. et al. Mid-infrared optical properties of thin films of aluminum oxide, titanium dioxide, silicon dioxide, aluminum nitride, and silicon nitride. Applied Optics 51, 6789, https://doi.org/10.1364/ao.51.006789 (2012).

Wahlstrand, J. K., Cheng, Y.-H. & Milchberg, H. M. Absolute measurement of the transient optical nonlinearity in N2, O2, N2O, and Ar. Physical Review A 85, https://doi.org/10.1103/physreva.85.043820 (2012).

Althoff, R. & Hertz, J. Measurement of the optical constants of Na and K in the range of wavelength from 2.5 to 10 μ. Infrared Physics 7, 11–16, https://doi.org/10.1016/0020-0891(67)90025-5 (1967).

Kato, K., Tanno, F. & Umemura, N. Sellmeier and thermo-optic dispersion formulas for GaSe (revisited). Applied Optics 52, 2325, https://doi.org/10.1364/ao.52.002325 (2013).

Pennington, D. M., Henesian, M. A. & Hellwarth, R. W. Nonlinear index of air at 1.053 μm. Physical Review A 39, 3003–3009, https://doi.org/10.1103/physreva.39.3003 (1989).

In another example, found at data-nk/main/Si/Aspnes.yml, n(λ) and k(λ) for Silicon (Si) are provided in tabulated numerical form:

Larruquert, J. I., Méndez, J. A. & Aznárez, J. A. Optical constants of aluminum films in the extreme ultraviolet interval of 82–77 nm. Applied Optics 35, 5692, https://doi.org/10.1364/ao.35.005692 (1996).

Mathar, R. J. Refractive index of humid air in the infrared: model fits. Journal of Optics A: Pure and Applied Optics 9, 470–476, https://doi.org/10.1088/1464-4258/9/5/008 (2007).

Selivanov, A., Denisov, I., Kuleshov, N. & Yumashev, K. Nonlinear refractive properties of Yb3+-doped KY(WO4)2 and YVO4 laser crystals. Applied Physics B 83, 61–65, https://doi.org/10.1007/s00340-005-2098-5 (2006).

‘DIVIDER’ assists in visually and logically separating related materials or data records, enhancing the navigation experience.

The described dataset5 is a collection of human-readable YAML files, meticulously organized for user convenience. While these files can be directly individually accessed for specific optical constants of materials, organizing them in a logically-structured way and employing computer programs for data retrieval and analysis unleashes the dataset’s comprehensive utility. The YAML format, a standardized data serialization language, ensures that the data files are easily parsable with libraries such as PyYAML for Python and libyaml for C/C++.

Adair, R., Chase, L. L. & Payne, S. A. Nonlinear refractive-index measurements of glasses using three-wave frequency mixing. Journal of the Optical Society of America B 4, 875, https://doi.org/10.1364/josab.4.000875 (1987).

Cunningham, P. D. et al. Broadband terahertz characterization of the refractive index and absorption of some important polymeric and organic electro-optic materials. Journal of Applied Physics 109, 043505–043505–5, https://doi.org/10.1063/1.3549120 (2011).

Ciesielski, A. et al. Evidence of germanium segregation in gold thin films. Surface Science 674, 73–78, https://doi.org/10.1016/j.susc.2018.03.020 (2018).

Song, B. et al. Broadband optical properties of graphene and hopg investigated by spectroscopic Mueller matrix ellipsometry. Applied Surface Science 439, 1079–1087, https://doi.org/10.1016/j.apsusc.2018.01.051 (2018).

We introduce the refractiveindex.info database, a comprehensive open-source repository containing optical constants for a wide array of materials, and describe in detail the underlying dataset. This collection, derived from a meticulous compilation of data sourced from peer-reviewed publications, manufacturers’ datasheets, and authoritative texts, aims to advance research in optics and photonics. The data is stored using a YAML-based format, ensuring integrity, consistency, and ease of access. Each record is accompanied by detailed metadata, facilitating a comprehensive understanding and efficient utilization of the data. In this descriptor, we outline the data curation protocols and the file format used for data records, and briefly demonstrate how the data can be organized in a user-friendly fashion akin to the books in a traditional library.

Mansfield, C. R. & Peck, E. R. Dispersion of helium. Journal of the Optical Society of America 59, 199, https://doi.org/10.1364/josa.59.000199 (1969).

Yamaguchi, S. & Hanyu, T. The optical properties of Rb. Journal of the Physical Society of Japan 35, 1371–1377, https://doi.org/10.1143/jpsj.35.1371 (1973).

Graphical-only data: Occasionally, authors choose to include only graphical data in publications without numerical data. In such cases, we first attempt to contact the authors for the original data. If this is not feasible (in the case of older publications) or if there is no response, semi-automatic digitization of the plots is sometimes performed (e.g., using Engauge Digitizer software); however, this is considered a last resort due to its time-consuming and less accurate nature and is typically used only when no alternative data is available.

Larruquert, J. I. et al. Self-consistent optical constants of SiC thin films. Journal of the Optical Society of America A 28, 2340, https://doi.org/10.1364/josaa.28.002340 (2011).

Numericalapertureof optical fiber

Nibbering, E. T. J., Grillon, G., Franco, M. A., Prade, B. S. & Mysyrowicz, A. Determination of the inertial contribution to the nonlinear refractive index of air, N2, and O2 by use of unfocused high-intensity femtosecond laser pulses. Journal of the Optical Society of America B 14, 650, https://doi.org/10.1364/josab.14.000650 (1997).

Green, M. A. Self-consistent optical parameters of intrinsic silicon at 300 K including temperature coefficients. Solar Energy Materials and Solar Cells 92, 1305–1310, https://doi.org/10.1016/j.solmat.2008.06.009 (2008).

Ordal, M. A., Bell, R. J., Alexander, R. W., Long, L. L. & Querry, M. R. Optical properties of fourteen metals in the infrared and far infrared: Al, Co, Cu, Au, Fe, Pb, Mo, Ni, Pd, Pt, Ag, Ti, V, and W. Applied Optics 24, 4493, https://doi.org/10.1364/ao.24.004493 (1985).

Beadie, G., Brindza, M., Flynn, R. A., Rosenberg, A. & Shirk, J. S. Refractive index measurements of poly(methyl methacrylate) (PMMA) from 0.4—1.6 μm. Applied Optics 54, F139, https://doi.org/10.1364/ao.54.00f139 (2015).

Li, H. H. Refractive index of silicon and germanium and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data 9, 561–658, https://doi.org/10.1063/1.555624 (1980).

The library is defined by two catalog files: catalog-nk.yml for linear optical properties and catalog-n2.yml for nonlinear properties. Below is an excerpt from the catalog-n2.yml file, exemplifying the integration of HTML typesetting and showcasing optional entries like ‘DIVIDER’ and ‘info’. The ‘DIVIDER’ is employed to separate distinct groups of books or pages clearly, while ‘info’ links to an HTML file furnishing extra details about a particular shelf, book, or page.

Zelmon, D. E., Small, D. L. & Page, R. Refractive-index measurements of undoped yttrium aluminum garnet from 04 to 50 μm. Applied Optics 37, 4933, https://doi.org/10.1364/ao.37.004933 (1998).

Hurlbut, W. C., Lee, Y.-S., Vodopyanov, K. L., Kuo, P. S. & Fejer, M. M. Multiphoton absorption and nonlinear refraction of GaAs in the mid-infrared. Optics Letters 32, 668, https://doi.org/10.1364/ol.32.000668 (2007).

Chen, C.-W. et al. Optical properties of organometal halide perovskite thin films and general device structure design rules for perovskite single and tandem solar cells. Journal of Materials Chemistry A 3, 9152–9159, https://doi.org/10.1039/c4ta05237d (2015).

To aid users in navigating the data, two Python scripts, nkexplorer.py and n2explorer.py, are housed in the tools folder in the root directory of the refractiveindex.info database. These utilities, boasting a QT-based graphical interface, facilitate the location and comparison of data from a variety of sources. Figure 1 displays the n2explorer.py interface, illustrating the visual comparison of n2 data for SiO2 sourced from multiple publications.

Svechnikov, M. et al. Optical constants of sputtered beryllium thin films determined from photoabsorption measurements in the spectral range 20.4–250 eV. Journal of Synchrotron Radiation 27, 75–82, https://doi.org/10.1107/s1600577519014188 (2020).

DeBell, A. G. et al. Cryogenic refractive indices and temperature coefficients of cadmium telluride from 6 μm to 22 μm. Applied Optics 18, 3114, https://doi.org/10.1364/ao.18.003114 (1979).

Zhang, H. et al. Measuring the refractive index of highly crystalline monolayer MoS2 with high confidence. Scientific Reports 5, https://doi.org/10.1038/srep08440 (2015).

The resolving power of an objective determines the size of the formed Airy diffraction pattern: The radius of the central disk is determined by the combined numerical apertures of the objective and condenser. When condenser and objective have equivalent numerical apertures or the objective acts also as the condenser like in an inverted fluorescence microscope, the Airy pattern radius from the central peak to the first minimum is given by the equation:

Lin, M., Sverdlov, B., Strite, S., Morkoç, H. & Drakin, A. Refractive indices of wurtzite and zincblende GaN. Electronics Letters 29, 1759, https://doi.org/10.1049/el:19931172 (1993).

Coulter, J. K., Hass, G. & Ramsey, J. B. Optical constants and reflectance and transmittance of evaporated rhodium films in the visible. Journal of the Optical Society of America 63, 1149, https://doi.org/10.1364/josa.63.001149 (1973).

Tabulated numerical data: In cases where optical constants are presented in tabulated numerical form, the data are transferred to the data record with minimal changes required by the used format (e.g., using micrometer as the unit of wavelength and expressing internal absorption by extinction coefficient k). This process is simplified if data is in a standard table format (e.g., CSV or Microsoft Excel) in supplementary materials or directly provided by authors. For older publications, typically available as bitmap-based PDF files, text recognition options in PDF reading software prove helpful.

Beliaev, L. Y., Shkondin, E., Lavrinenko, A. V. & Takayama, O. Thickness-dependent optical properties of aluminum nitride films for mid-infrared wavelengths. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 39, https://doi.org/10.1116/6.0000884 (2021).

Jellison, G. Optical functions of GaAs, GaP, and Ge determined by two-channel polarization modulation ellipsometry. Optical Materials 1, 151–160, https://doi.org/10.1016/0925-3467(92)90022-f (1992).

Daimon, M. & Masumura, A. Measurement of the refractive index of distilled water from the near-infrared region to the ultraviolet region. Applied Optics 46, 3811, https://doi.org/10.1364/ao.46.003811 (2007).

The dataset described here, which represents the core of the refractiveindex.info database, is available at Figshare5. It presently (as of December 2023) contains 3135 data records on 605 materials in the part of the dataset corresponding to linear optical properties (nk), and 193 records on 89 materials in the part corresponding to nonlinear optical properties (n2).

Rowe, P. M., Fergoda, M. & Neshyba, S. Temperature-dependent optical properties of liquid water from 240 to 298 K. Journal of Geophysical Research: Atmospheres 125, https://doi.org/10.1029/2020jd032624 (2020).

Zhukovsky, S. V. et al. Experimental demonstration of effective medium approximation breakdown in deeply subwavelength all-dielectric multilayers. Physical Review Letters 115, https://doi.org/10.1103/physrevlett.115.177402 (2015).

Polyanskiy, M.N. Refractiveindex.info database of optical constants. Sci Data 11, 94 (2024). https://doi.org/10.1038/s41597-023-02898-2

Arosa, Y. & de la Fuente, R. Refractive index spectroscopy and material dispersion in fused silica glass. Optics Letters 45, 4268, https://doi.org/10.1364/ol.395510 (2020).

Fernández-Perea, M. et al. Transmittance and optical constants of Ce films in the 6–1200ev spectral range. Journal of Applied Physics 103, https://doi.org/10.1063/1.2901137 (2008).

Boyd, G., Kasper, H. & McFee, J. Linear and nonlinear optical properties of AgGaS2, CuGaS2, and CuInS2, and theory of the wedge technique for the measurement of nonlinear coefficients. IEEE Journal of Quantum Electronics 7, 563–573, https://doi.org/10.1109/jqe.1971.1076588 (1971).

Ensley, T. R. & Bambha, N. K. Ultrafast nonlinear refraction measurements of infrared transmitting materials in the mid-wave infrared. Optics Express 27, 37940, https://doi.org/10.1364/oe.380702 (2019).

Pettit, G. D. & Turner, W. J. Refractive index of InP. Journal of Applied Physics 36, 2081–2081, https://doi.org/10.1063/1.1714410 (1965).

Zelmon, D. E., Small, D. L. & Jundt, D. Infrared corrected Sellmeier coefficients for congruently grown lithium niobate and 5 mol% magnesium oxide-doped lithium niobate. Journal of the Optical Society of America B 14, 3319, https://doi.org/10.1364/josab.14.003319 (1997).

Moutzouris, K., Hloupis, G., Stavrakas, I., Triantis, D. & Chou, M.-H. Temperature-dependent visible to near-infrared optical properties of 8 mol% Mg-doped lithium tantalate. Optical Materials Express 1, 458, https://doi.org/10.1364/ome.1.000458 (2011).

Vidal-Dasilva, M. et al. Transmittance and optical constants of Tm films in the 2.75–1600 eV spectral range. Journal of Applied Physics 105, https://doi.org/10.1063/1.3129507 (2009).

Unless explicitly defined, non-prefixed SI units (e.g., watts, meters, seconds) are the default to ensure unambiguous and standardized data representation and interpretation. For instance, n2 is expressed in units of m2/W. However, an exception exists for the wavelength, which is always specified in micrometers to comply with a general practice accepted in optical design and, in particular, to allow the direct use of published dispersion formulas that traditionally assume wavelength expressed in micrometers.

Adachi, S. Optical dispersion relations for AlSb from E=0 to 6.0 eV. Journal of Applied Physics 67, 6427–6431, https://doi.org/10.1063/1.345115 (1990).

Li, J., Wen, C.-H., Gauza, S., Lu, R. & Wu, S.-T. Refractive indices of liquid crystals for display applications. Journal of Display Technology 1, 51–61, https://doi.org/10.1109/jdt.2005.853357 (2005).

Stelling, C. et al. Plasmonic nanomeshes: their ambivalent role as transparent electrodes in organic solar cells. Scientific Reports 7, https://doi.org/10.1038/srep42530 (2017).

Models: If a reference presents a model for calculating optical constants, a Python script is developed to generate a tabulated data record compatible with the required format. This script is then made publicly available to refractiveindex.info users on GitHub.

Rodríguez-de Marcos, L. et al. Transmittance and optical constants of Sr films in the 6–1220 eV spectral range. Journal of Applied Physics 111, https://doi.org/10.1063/1.4729487 (2012).

David, M. et al. Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications. Optical Materials Express 12, 2168, https://doi.org/10.1364/ome.458667 (2022).

Sneep, M. & Ubachs, W. Direct measurement of the Rayleigh scattering cross section in various gases. Journal of Quantitative Spectroscopy and Radiative Transfer 92, 293–310, https://doi.org/10.1016/j.jqsrt.2004.07.025 (2005).

Salzberg, C. D. & Villa, J. J. Infrared refractive indexes of silicon germanium and modified selenium glass. Journal of the Optical Society of America 47, 244, https://doi.org/10.1364/josa.47.000244 (1957).

Dispersion formula: When the linear refractive index as a function of wavelength is given as a dispersion formula, the coefficients are manually transferred to the data record. Adjustments are made if necessary to fit the formula to one of the standard forms documented in the following section.

Bideau-Mehu, A., Guern, Y., Abjean, R. & Johannin-Gilles, A. Measurement of refractive indices of neon, argon, krypton and xenon in the 253.7—140.4 nm wavelength range. dispersion relations and estimated oscillator strengths of the resonance lines. Journal of Quantitative Spectroscopy and Radiative Transfer 25, 395–402, https://doi.org/10.1016/0022-4073(81)90057-1 (1981).

Aspnes, D. E., Kelso, S. M., Logan, R. A. & Bhat, R. Optical properties of AlxGa1-xAs. Journal of Applied Physics 60, 754–767, https://doi.org/10.1063/1.337426 (1986).

Schnepf, M. J. et al. Nanorattles with tailored electric field enhancement. Nanoscale 9, 9376–9385, https://doi.org/10.1039/c7nr02952g (2017).

Shkondin, E. et al. Large-scale high aspect ratio Al-doped ZnO nanopillars arrays as anisotropic metamaterials. Optical Materials Express 7, 1606, https://doi.org/10.1364/ome.7.001606 (2017).

Rakić, A. D. Algorithm for the determination of intrinsic optical constants of metal films: application to aluminum. Applied Optics 34, 4755, https://doi.org/10.1364/ao.34.004755 (1995).

Panah, M. E. A. et al. Highly doped inp as a low loss plasmonic material for mid-IR region. Optics Express 24, 29077, https://doi.org/10.1364/oe.24.029077 (2016).

Peck, E. R. & Khanna, B. N. Dispersion of nitrogen. Journal of the Optical Society of America 56, 1059, https://doi.org/10.1364/josa.56.001059 (1966).

Fern, R. E. & Onton, A. Refractive index of AlAs. Journal of Applied Physics 42, 3499–3500, https://doi.org/10.1063/1.1660760 (1971).

Valentine, J. et al. Three-dimensional optical metamaterial with a negative refractive index. Nature 455, 376–379, https://doi.org/10.1038/nature07247 (2008).

Ermolaev, G. A. et al. Spectroscopic ellipsometry of large area monolayer WS2 and WSe2 films. In AIP Conference Proceedings, https://doi.org/10.1063/5.0054947 (AIP Publishing, 2021).

Jung, G.-H., Yoo, S. & Park, Q.-H. Measuring the optical permittivity of two-dimensional materials without a priori knowledge of electronic transitions. Nanophotonics 8, 263–270, https://doi.org/10.1515/nanoph-2018-0120 (2018).

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Lisitsa, M. P., Gudymenko, L. F., Malinko, V. N. & Terekhova, S. F. Dispersion of the refractive indices and birefringence of CdSxSe1-x single crystals. physica status solidi (b) 31, 389–399, https://doi.org/10.1002/pssb.19690310146 (1969).

In n2 datasets, the data are always presented numerically. An example can be found at data-n2/main/SiO2/Flom.yml. n2 is expressed in m2/W:

Magnozzi, M., Ferrera, M., Mattera, L., Canepa, M. & Bisio, F. Plasmonics of au nanoparticles in a hot thermodynamic bath. Nanoscale 11, 1140–1146, https://doi.org/10.1039/c8nr09038f (2019).

Lin, Q. et al. Dispersion of silicon nonlinearities in the near infrared region. Applied Physics Letters 91, https://doi.org/10.1063/1.2750523 (2007).

Lee, S., Jeong, T., Jung, S. & Yee, K. Refractive index dispersion of hexagonal boron nitride in the visible and near-infrared. physica status solidi (b) 256, https://doi.org/10.1002/pssb.201800417 (2018).

Polyanskiy, M. N. et al. Single-shot measurement of the nonlinear refractive index of air at 9.2 μm with a picosecond terawatt CO2 laser. Optics Letters 46, 2067, https://doi.org/10.1364/ol.423800 (2021).

Schinke, C., Hinken, D., Schmidt, J., Bothe, K. & Brendel, R. Modeling the spectral luminescence emission of silicon solar cells and wafers. IEEE Journal of Photovoltaics 3, 1038–1052, https://doi.org/10.1109/jphotov.2013.2263985 (2013).

Giannios, P. et al. Visible to near-infrared refractive properties of freshly-excised human-liver tissues: marking hepatic malignancies. Scientific Reports 6, https://doi.org/10.1038/srep27910 (2016).

Islam, K. M. et al. In-plane and out-of-plane optical properties of monolayer, few-layer, and thin-film MoS2 from 190 to 1700 nm and their application in photonic device design. Advanced Photonics Research 2, https://doi.org/10.1002/adpr.202000180 (2021).

Schinke, C. et al. Uncertainty analysis for the coefficient of band-to-band absorption of crystalline silicon. AIP Advances 5, https://doi.org/10.1063/1.4923379 (2015).

Malitson, I. H. Interspecimen comparison of the refractive index of fused silica. Journal of the Optical Society of America 55, 1205, https://doi.org/10.1364/josa.55.001205 (1965).

Hartnett, T., Bernstein, S., Maguire, E. & Tustison, R. Optical properties of ALON (aluminum oxynitride). Infrared Physics & Technology 39, 203–211, https://doi.org/10.1016/s1350-4495(98)00007-3 (1998).

Werner, W. S. M., Glantschnig, K. & Ambrosch-Draxl, C. Optical constants and inelastic electron-scattering data for 17 elemental metals. Journal of Physical and Chemical Reference Data 38, 1013–1092, https://doi.org/10.1063/1.3243762 (2009).

Owyoung, A. Ellipse rotation studies in laser host materials. IEEE Journal of Quantum Electronics 9, 1064–1069, https://doi.org/10.1109/jqe.1973.1077417 (1973).

Ratzsch, S., Kley, E.-B., Tünnermann, A. & Szeghalmi, A. Influence of the oxygen plasma parameters on the atomic layer deposition of titanium dioxide. Nanotechnology 26, 024003, https://doi.org/10.1088/0957-4484/26/2/024003 (2014).

Wettling, W. & Windscheif, J. Elastic constants and refractive index of boron phosphide. Solid State Communications 50, 33–34, https://doi.org/10.1016/0038-1098(84)90053-x (1984).

Vukovic, D., Woolsey, G. A. & Scelsi, G. B. Refractivities of SF6 and SOF2 at wavelengths of 632.99 and 1300 nm. Journal of Physics D: Applied Physics 29, 634–637, https://doi.org/10.1088/0022-3727/29/3/023 (1996).

Beliaev, L. Y., Shkondin, E., Lavrinenko, A. V. & Takayama, O. Optical properties of plasmonic titanium nitride thin films from ultraviolet to mid-infrared wavelengths deposited by pulsed-DC sputtering, thermal and plasma-enhanced atomic layer deposition. Optical Materials 143, 114237, https://doi.org/10.1016/j.optmat.2023.114237 (2023).

Weaver, J. H., Olson, C. G. & Lynch, D. W. Optical investigation of the electronic structure of bulk Rh and Ir. Physical Review B 15, 4115–4118, https://doi.org/10.1103/physrevb.15.4115 (1977).

In the case of a data record for linear optical constants, the DATA field can be specified as a dispersion formula, identified by a formula number, or as tabulated data sets of n(λ) and/or k(λ). For dispersion formulas, the ‘wavelength_range’ entry indicates the applicable wavelength range for the data, always expressed in micrometers. Each dispersion formula in the database is numerically identified and described as follows:

Zhang, X., Qiu, J., Zhao, J., Li, X. & Liu, L. Complex refractive indices measurements of polymers in infrared bands. Journal of Quantitative Spectroscopy and Radiative Transfer 252, 107063, https://doi.org/10.1016/j.jqsrt.2020.107063 (2020).

Ghosh, G. Dispersion-equation coefficients for the refractive index and birefringence of calcite and quartz crystals. Optics Communications 163, 95–102, https://doi.org/10.1016/s0030-4018(99)00091-7 (1999).

El-Kashef, H. The necessary requirements imposed on polar dielectric laser dye solvents. Physica B: Condensed Matter 279, 295–301, https://doi.org/10.1016/s0921-4526(99)00856-x (2000).

Sani, E. & Dell’Oro, A. Optical constants of ethylene glycol over an extremely wide spectral range. Optical Materials 37, 36–41, https://doi.org/10.1016/j.optmat.2014.04.035 (2014).

Bristow, A. D., Rotenberg, N. & van Driel, H. M. Two-photon absorption and kerr coefficients of silicon for 850–2200nm. Applied Physics Letters 90, https://doi.org/10.1063/1.2737359 (2007).

Ishteev, A. et al. Investigation of structural and optical properties of MAPbBr3 monocrystals under fast electron irradiation. Journal of Materials Chemistry C 10, 5821–5828, https://doi.org/10.1039/d2tc00128d (2022).

Fang, S., Liu, H., Huang, L. & Ye, N. Growth and optical properties of nonlinear LuAl3(BO3)4 crystals. Optics Express 21, 16415, https://doi.org/10.1364/oe.21.016415 (2013).

Moerland, R. J. & Hoogenboom, J. P. Subnanometer-accuracy optical distance ruler based on fluorescence quenching by transparent conductors. Optica 3, 112, https://doi.org/10.1364/optica.3.000112 (2016).

The COMMENTS field can incorporate additional information to provide context to the data, while the SPECS field presents structured data in key-value pairs, giving machine-interpretable insights into specific measurement conditions or additional properties.

Giannios, P. et al. Complex refractive index of normal and malignant human colorectal tissue in the visible and near-infrared. Journal of Biophotonics 10, 303–310, https://doi.org/10.1002/jbio.201600001 (2016).

Cuthbertson, C. & Cuthbertson, M. The refraction and dispersion of argon, and redeterminations of the dispersion of helium, neon, krypton, and xenon. Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character 84, 13–15, https://doi.org/10.1098/rspa.1910.0052 (1910).

Jiang, Y., Pillai, S. & Green, M. A. Realistic silver optical constants for plasmonics. Scientific Reports 6, https://doi.org/10.1038/srep30605 (2016).

Siefke, T. et al. Materials pushing the application limits of wire grid polarizers further into the deep ultraviolet spectral range. Advanced Optical Materials 4, 1780–1786, https://doi.org/10.1002/adom.201600250 (2016).

Rodney, W. S. Optical properties of cesium iodide. Journal of the Optical Society of America 45, 987, https://doi.org/10.1364/josa.45.000987 (1955).

Herguedas, N. & Carretero, E. Optical properties in mid-infrared range of silicon oxide thin films with different stoichiometries. Nanomaterials 13, 2749, https://doi.org/10.3390/nano13202749 (2023).

Kachare, A. H., Spitzer, W. G. & Fredrickson, J. E. Refractive index of ion-implanted GaAs. Journal of Applied Physics 47, 4209–4212, https://doi.org/10.1063/1.323292 (1976).

Leguy, A. M. A. et al. Reversible hydration of CH3NH3PbI3 in films, single crystals, and solar cells. Chemistry of Materials 27, 3397–3407, https://doi.org/10.1021/acs.chemmater.5b00660 (2015).

Ferrera, M., Magnozzi, M., Bisio, F. & Canepa, M. Temperature-dependent permittivity of silver and implications for thermoplasmonics. Physical Review Materials 3, https://doi.org/10.1103/physrevmaterials.3.105201 (2019).

Ermolaev, G. A. et al. Giant optical anisotropy in transition metal dichalcogenides for next-generation photonics. Nature Communications 12, https://doi.org/10.1038/s41467-021-21139-x (2021).

DATA: - type: tabulated n2 data: | 0.772 2.07e-20 1.030 2.23e-20 1.550 2.42e-20 SPECS: n2_method: Z-scan pulse_duration: 280e-15 140e-15 97e-15

Brasse, Y. et al. Magnetic and electric resonances in particle-to-film-coupled functional nanostructures. ACS Applied Materials & Interfaces 10, 3133–3141, https://doi.org/10.1021/acsami.7b16941 (2018).

Luke, K., Okawachi, Y., Lamont, M. R. E., Gaeta, A. L. & Lipson, M. Broadband mid-infrared frequency comb generation in a Si3N4 microresonator. Optics Letters 40, 4823, https://doi.org/10.1364/ol.40.004823 (2015).

Adhering strictly to the syntactical rules of YAML is paramount. This adherence includes the mandatory use of spaces for indentation (tabs are prohibited) and the application of UTF-8 encoding without BOM, ensuring consistency and readability across diverse data records. While not a stringent requirement, a uniform format for similar entries, particularly references, is encouraged to optimize the user experience and enhance data interpretability.

Malitson, I. H. Refractive properties of barium fluoride. Journal of the Optical Society of America 54, 628, https://doi.org/10.1364/josa.54.000628 (1964).

Tan, C. Determination of refractive index of silica glass for infrared wavelengths by IR spectroscopy. Journal of Non-Crystalline Solids 223, 158–163, https://doi.org/10.1016/s0022-3093(97)00438-9 (1998).

Whang, U. S., Arakawa, E. T. & Callcott, T. A. Optical properties of Rb between 3.3 and 10.5 eV. Physical Review B 5, 2118–2124, https://doi.org/10.1103/physrevb.5.2118 (1972).

Otanicar, T. P., Phelan, P. E. & Golden, J. S. Optical properties of liquids for direct absorption solar thermal energy systems. Solar Energy 83, 969–977, https://doi.org/10.1016/j.solener.2008.12.009 (2009).

Suzuki, N., Sawai, K. & Adachi, S. Optical properties of PbSe. Journal of Applied Physics 77, 1249–1255, https://doi.org/10.1063/1.358926 (1995).

Inagaki, T., Arakawa, E. T., Birkhoff, R. D. & Williams, M. W. Optical properties of liquid Na between 0.6 and 3.8 eV. Physical Review B 13, 5610–5612, https://doi.org/10.1103/physrevb.13.5610 (1976).

Rheims, J., Köser, J. & Wriedt, T. Refractive-index measurements in the near-IR using an Abbe refractometer. Measurement Science and Technology 8, 601–605, https://doi.org/10.1088/0957-0233/8/6/003 (1997).

Glass catalogs: Glass makers’ catalogs in AGF format are automatically converted into refractiveindex.info data records using a dedicated Python script.

Logothetidis, S., Petalas, J., Cardona, M. & Moustakas, T. D. Optical properties and temperature dependence of the interband transitions of cubic and hexagonal GaN. Physical Review B 50, 18017–18029, https://doi.org/10.1103/physrevb.50.18017 (1994).

Boyd, G., Kasper, H., McFee, J. & Storz, F. Linear and nonlinear optical properties of some ternary selenides. IEEE Journal of Quantum Electronics 8, 900–908, https://doi.org/10.1109/jqe.1972.1076900 (1972).

Rubin, M. Optical properties of soda lime silica glasses. Solar Energy Materials 12, 275–288, https://doi.org/10.1016/0165-1633(85)90052-8 (1985).

Barnes, N. P. & Gettemy, D. J. Temperature variation of the refractive indices of yttrium lithium fluoride. Journal of the Optical Society of America 70, 1244, https://doi.org/10.1364/josa.70.001244 (1980).

Meretska, M. L. et al. Measurements of the magneto-optical properties of thin-film EuS at room temperature in the visible spectrum. Applied Physics Letters 120, https://doi.org/10.1063/5.0090533 (2022).

Hulme, K. F., Jones, O., Davies, P. H. & Hobden, M. V. Synthetic proustite (Ag3AsS3): A new crystal for optical mixing. Applied Physics Letters 10, 133–135, https://doi.org/10.1063/1.1754880 (1967).

Schmitt, P. et al. Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications. Optical Materials Express 12, 545, https://doi.org/10.1364/ome.447306 (2022).

Zemel, J. N., Jensen, J. D. & Schoolar, R. B. Electrical and optical properties of epitaxial films of PbS, PbSe, PbTe, and SnTe. Physical Review 140, A330–A342, https://doi.org/10.1103/physrev.140.a330 (1965).

Birkhoff, R. D., Painter, L. R. & Heller, J. M. Optical and dielectric functions of liquid glycerol from gas photoionization measurements. The Journal of Chemical Physics 69, 4185–4188, https://doi.org/10.1063/1.437098 (1978).

Vogt, M. R. et al. Measurement of the optical constants of soda-lime glasses in dependence of iron content and modeling of iron-related power losses in crystalline si solar cell modules. IEEE Journal of Photovoltaics 6, 111–118, https://doi.org/10.1109/jphotov.2015.2498043 (2016).

Gant, P. et al. Optical contrast and refractive index of natural van der waals heterostructure nanosheets of franckeite. Beilstein Journal of Nanotechnology 8, 2357–2362, https://doi.org/10.3762/bjnano.8.235 (2017).

Pastrňák, J. & Roskovcová, L. Refraction index measurements on AlN single crystals. physica status solidi (b) 14, https://doi.org/10.1002/pssb.19660140127 (1966).

Inclusion of additional information on optical glasses makes the data records suitable for use in optical design software.

Kerremans, R. et al. The optical constants of solution-processed semiconductors—new challenges with perovskites and non-fullerene acceptors. Advanced Optical Materials 8, https://doi.org/10.1002/adom.202000319 (2020).

Ciesielski, A., Skowronski, L., Pacuski, W. & Szoplik, T. Permittivity of ge, te and se thin films in the 200–1500 nm spectral range. predicting the segregation effects in silver. Materials Science in Semiconductor Processing 81, 64–67, https://doi.org/10.1016/j.mssp.2018.03.003 (2018).

Zelmon, D. E., Bayya, S. S., Sanghera, J. S. & Aggarwal, I. D. Dispersion of barium gallogermanate glass. Applied Optics 41, 1366, https://doi.org/10.1364/ao.41.001366 (2002).

Křen, P. Comment on “Precision refractive index measurements of air, N2, O2, Ar, and CO2 with a frequency comb”. Applied Optics 50, 6484, https://doi.org/10.1364/ao.50.006484 (2011).

The refractiveindex.info database is build upon the dataset described in the previous sections and include additions aimed at simplifying the access and navigation through the data. The main addition is a descriptor defining a hierarchical structure akin to a library. In this setup, each data record is akin to a "page," housed within a "book," and all such books are systematically arranged on different "shelves." This logical structure is defined and maintained through YAML-based catalog files, that categorize each data record following the ‘library’ analogy and indicate the relative path of the corresponding data records.

Barnes, N. P. & Piltch, M. S. Temperature-dependent Sellmeier coefficients and nonlinear optics average power limit for germanium. Journal of the Optical Society of America 69, 178, https://doi.org/10.1364/josa.69.000178 (1979).

Leonard, P. Refractive indices, verdet constants, and polarizabilities of the inert gases. Atomic Data and Nuclear Data Tables 14, 21–37, https://doi.org/10.1016/s0092-640x(74)80028-8 (1974).

Boyd, G., Buehler, E., Storz, F. & Wernick, J. Linear and nonlinear optical properties of ternary AIIBIVC2V chalcopyrite semiconductors. IEEE Journal of Quantum Electronics 8, 419–426, https://doi.org/10.1109/jqe.1972.1076982 (1972).

Verification of accuracy of data extraction: Several tests are used to ensure the absence of errors in the conversion process:

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Djurišić, A., Li, E., Rakić, D. & Majewski, M. Modeling the optical properties of AlSb, GaSb, and InSb. Applied Physics A: Materials Science & Processing 70, 29–32, https://doi.org/10.1007/s003390050006 (2000).

Shaw, M., Hooker, C. & Wilson, D. Measurement of the nonlinear refractive index of air and other gases at 248 nm. Optics Communications 103, 153–160, https://doi.org/10.1016/0030-4018(93)90657-q (1993).

Simon, M. et al. Refractive indices of photorefractive bismuth titanate, barium-calcium titanate, bismuth germanium oxide, and lead germanate. physica status solidi (a) 159, 559–562, 10.1002/1521-396x(199702)159:2<559::aid-pssa559>3.0.co;2-0 (1997).

Weaver, J. H., Olson, C. G. & Lynch, D. W. Optical properties of crystalline tungsten. Physical Review B 12, 1293–1297, https://doi.org/10.1103/physrevb.12.1293 (1975).

Martonchik, J. V. & Orton, G. S. Optical constants of liquid and solid methane. Applied Optics 33, 8306, https://doi.org/10.1364/ao.33.008306 (1994).

Zhang, Z. M., Lefever-Button, G. & Powell, F. R. Infrared refractive index and extinction coefficient of polyimide films. International Journal of Thermophysics 19, 905–916, https://doi.org/10.1023/a:1022655309574 (1998).

Wood, D. L., Nassau, K., Kometani, T. Y. & Nash, D. L. Optical properties of cubic hafnia stabilized with yttria. Applied Optics 29, 604, https://doi.org/10.1364/ao.29.000604 (1990).

Philipp, H. R., Cole, H. S., Liu, Y. S. & Sitnik, T. A. Optical absorption of some polymers in the region 240–170 nm. Applied Physics Letters 48, 192–194, https://doi.org/10.1063/1.96940 (1986).

Rodney, W. S., Malitson, I. H. & King, T. A. Refractive index of arsenic trisulfide. Journal of the Optical Society of America 48, 633, https://doi.org/10.1364/josa.48.000633 (1958).

Seçkin, S., Singh, P., Jaiswal, A. & König, T. A. F. Super-radiant sers enhancement by plasmonic particle gratings. ACS Applied Materials & Interfaces 15, 43124–43134, https://doi.org/10.1021/acsami.3c07532 (2023).

The author declares no competing interests. However, for complete transparency, it is noted that the author is the owner of the RefractiveIndex.INFO website, which utilizes the refractiveindex.info database to provide optical constants. The website generates modest revenue from advertisements, which primarily covers maintenance expenses including web hosting, domain registration, and email services.

Connolly, J., diBenedetto, B. & Donadio, R. Specifications of raytran material. In Fischer, R. E. (ed.) Contemporary Optical Systems and Components Specifications, https://doi.org/10.1117/12.957359 (SPIE, 1979).

Woods, B. W., Payne, S. A., Marion, J. E., Hughes, R. S. & Davis, L. E. Thermomechanical and thermo-optical properties of the LiCaAlF6:Cr3+ laser material. Journal of the Optical Society of America B 8, 970, https://doi.org/10.1364/josab.8.000970 (1991).

Looking for data abnormalities: A deviation of a data point from the general trend in the data record is usually an indication of a data extraction error. All such abnormalities are manually compared against the original data, and necessary corrections are made.

The tutorial starts with a pattern of Airy disks appearing in the focal plane of the microscope and the point-spread function / three dimensional of a corresponding, single Airy disk pattern shown on the right. To operate the tutorial, use the Numerical Aperture slider to change the objective´s numerical aperture and the resolution of the Airy patterns. The left position of the slider shows the pattern at the lowest objective numerical aperture (= 0.20), and the right position illustrates the highest degree of resolution (numerical aperture = 1.30). As the slider is moved from left to right, the objective’s numerical aperture increases and the complex Airy pattern, as visible in the image, results in a progressively increased resolution of image detail. Correspondingly, the central peak and higher-order diffraction rings in the three-dimensional Airy pattern drawing grow smaller in diameter.

Kaiser, W., Spitzer, W. G., Kaiser, R. H. & Howarth, L. E. Infrared properties of CaF2, SrF2, and BaF2. Physical Review 127, 1950–1954, https://doi.org/10.1103/physrev.127.1950 (1962).

Marcos, L. R.-d. et al. Optical constants of SrF2 thin films in the 25–780-eV spectral range. Journal of Applied Physics 113, https://doi.org/10.1063/1.4800099 (2013).

It is noteworthy that for n2, information on the measurement method and pulse duration is essential for comparing data from different sources. This information is specified in the optional SPECS field.

Ermolaev, G. A. et al. Anisotropic optical properties of monolayer aligned single-walled carbon nanotubes. physica status solidi (RRL) – Rapid Research Letters 2300199, https://doi.org/10.1002/pssr.202300199 (2023).

Carvajal, J. J. et al. Structural and optical properties of RbTiOPO4:Nb crystals. Journal of Physics: Condensed Matter 19, 116214, https://doi.org/10.1088/0953-8984/19/11/116214 (2007).

Jansonas, G., Budriūnas, R., Vengris, M. & Varanavičius, A. Interferometric measurements of nonlinear refractive index in the infrared spectral range. Optics Express 30, 30507, https://doi.org/10.1364/oe.458850 (2022).

Perner, L. W. et al. Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs. Physical Review Research 5, https://doi.org/10.1103/physrevresearch.5.033048 (2023).

Sasaki, T., Mori, Y. & Yoshimura, M. Progress in the growth of a CsLiB6O10 crystal and its application to ultraviolet light generation. Optical Materials 23, 343–351, https://doi.org/10.1016/s0925-3467(02)00316-6 (2003).

Miller, S. et al. Polarization-dependent nonlinear refractive index of BiB3O6. Optical Materials 30, 1469–1472, https://doi.org/10.1016/j.optmat.2007.11.015 (2008).

Plot comparison: We use Python scripts that automatically read YAML data record files and plot the included optical constants as a function of wavelength. Comparing these plots with those included in the original publications is a robust tool for spotting inconsistencies.

Vidal-Dasilva, M., Aquila, A. L., Gullikson, E. M., Salmassi, F. & Larruquert, J. I. Optical constants of magnetron-sputtered magnesium films in the 25–1300 eV energy range. Journal of Applied Physics 108, https://doi.org/10.1063/1.3481457 (2010).

Tamošauskas, G., Beresnevičius, G., Gadonas, D. & Dubietis, A. Transmittance and phase matching of BBO crystal in the 3–5 µm range and its application for the characterization of mid-infrared laser pulses. Optical Materials Express 8, 1410, https://doi.org/10.1364/ome.8.001410 (2018).

Kumar, A. et al. Linear and nonlinear optical properties of BiFeO3. Applied Physics Letters 92, https://doi.org/10.1063/1.2901168 (2008).

Beliaev, L. Y., Shkondin, E., Lavrinenko, A. V. & Takayama, O. Optical, structural and composition properties of silicon nitride films deposited by reactive radio-frequency sputtering, low pressure and plasma-enhanced chemical vapor deposition. Thin Solid Films 763, 139568, https://doi.org/10.1016/j.tsf.2022.139568 (2022).

Moutzouris, K. et al. Refractive, dispersive and thermo-optic properties of twelve organic solvents in the visible and near-infrared. Applied Physics B 116, 617–622, https://doi.org/10.1007/s00340-013-5744-3 (2013).

Larruquert, J. I., Méndez, J. A. & Aznárez, J. A. Far-ultraviolet reflectance measurements and optical constants of unoxidized aluminum films. Applied Optics 34, 4892, https://doi.org/10.1364/ao.34.004892 (1995).

Gomez, M. S., Guerra, J. M. & Vilches, F. Weighted nonlinear regression analysis of a Sellmeier expansion: comparison of several nonlinear fits of CdS dispersion. Applied Optics 24, 1147, https://doi.org/10.1364/ao.24.001147 (1985).

Kato, K., Umemura, N. & Petrov, V. Sellmeier and thermo-optic dispersion formulas for CdGa2S4 and their application to the nonlinear optics of Hg1-xCdxGa2S4. Optics Communications 386, 49–52, https://doi.org/10.1016/j.optcom.2016.10.054 (2017).

Lane, D. W. The optical properties and laser irradiation of some common glasses. Journal of Physics D: Applied Physics 23, 1727–1734, https://doi.org/10.1088/0022-3727/23/12/037 (1990).

Wu, Y. et al. Intrinsic optical properties and enhanced plasmonic response of epitaxial silver. Advanced Materials 26, 6106–6110, https://doi.org/10.1002/adma.201401474 (2014).

Beal, A. R. & Hughes, H. P. Kramers-Kronig analysis of the reflectivity spectra of 2H-MoS2, 2H-MoSe2 and 2H-MoTe2. Journal of Physics C: Solid State Physics 12, 881–890, https://doi.org/10.1088/0022-3719/12/5/017 (1979).

Cheng, F. et al. Epitaxial growth of atomically smooth aluminum on silicon and its intrinsic optical properties. ACS Nano 10, 9852–9860, https://doi.org/10.1021/acsnano.6b05556 (2016).

Vos, M. F. J., Macco, B., Thissen, N. F. W., Bol, A. A. & Kessels, W. M. M. E. Atomic layer deposition of molybdenum oxide from (NtBu)2(NMe2)2Mo and O2 plasma. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 34, https://doi.org/10.1116/1.4930161 (2015).

Feldman, A. & Horowitz, D. Refractive index of cuprous chloride*. Journal of the Optical Society of America 59, 1406, https://doi.org/10.1364/josa.59.001406 (1969).

Existing data collections: The initial sources for literature containing data on optical constants were published collections, such as those included in the Handbook of Optics4. The publications referenced therein constituted our initial list of data sources.

Krauter, P. et al. Optical phantoms with adjustable subdiffusive scattering parameters. Journal of Biomedical Optics 20, 105008, https://doi.org/10.1117/1.jbo.20.10.105008 (2015).

Wang, C. C., Tan, J. Y., Jing, C. Y. & Liu, L. H. Temperature-dependent optical constants of liquid isopropanol, n-butanol, and n-decane. Applied Optics 57, 3003, https://doi.org/10.1364/ao.57.003003 (2018).

Arakawa, E. T., Williams, M. W. & Inagaki, T. Optical properties of arc-evaporated carbon films between 0.6 and 3.8 eV. Journal of Applied Physics 48, 3176–3177, https://doi.org/10.1063/1.324057 (1977).

Song, B. et al. Giant gate-tunability of complex refractive index in semiconducting carbon nanotubes. ACS Photonics 7, 2896–2905, https://doi.org/10.1021/acsphotonics.0c01220 (2020).

Zhang, D., Kong, Y. & Zhang, J.-Y. Optical parametric properties of 532-nm-pumped beta-barium-borate near the infrared absorption edge. Optics Communications 184, 485–491, https://doi.org/10.1016/s0030-4018(00)00968-8 (2000).

Kato, K., Banerjee, S. & Umemura, N. Phase-matching properties of AgGa0.86In0.14S2 for three-wave interactions in the 0.615–10.5910 μm spectral range. Optical Materials Express 11, 2800, https://doi.org/10.1364/ome.428688 (2021).

Phillip, H. R. & Taft, E. A. Kramers-Kronig analysis of reflectance data for diamond. Physical Review 136, A1445–A1448, https://doi.org/10.1103/physrev.136.a1445 (1964).

All collected data are converted into a standardized format stored in human-readable YAML files, as detailed in the following section. This approach ensures consistency and facilitates easy access and manipulation by both users and computer programs.

Pflüger, J., Fink, J., Weber, W., Bohnen, K. P. & Crecelius, G. Dielectric properties of TiCx, TiNx, VCx, and VNx from 1.5 to 40 eV determined by electron-energy-loss spectroscopy. Physical Review B 30, 1155–1163, https://doi.org/10.1103/physrevb.30.1155 (1984).

Ermolaev, G. A. et al. Broadband optical properties of monolayer and bulk MoS2. npj 2D Materials and Applications 4, https://doi.org/10.1038/s41699-020-0155-x (2020).