A quantum cascade laser (QCL) is a semiconductor laser that emits in the mid- to far-infrared region of the electromagnetic spectrum. Contrary to the typical semiconductor lasers which emit radiation by recombination of electron-hole pairs across the band-gap, emission from QCLs results from inter-subband transitions in a repeated stack of quantum well semiconductor heterostructures.

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The University of Waterloo acknowledges that much of our work takes place on the traditional territory of the Neutral, Anishinaabeg, and Haudenosaunee peoples. Our main campus is situated on the Haldimand Tract, the land granted to the Six Nations that includes six miles on each side of the Grand River. Our active work toward reconciliation takes place across our campuses through research, learning, teaching, and community building, and is co-ordinated within the Office of Indigenous Relations.

QCLs illustrates the power of structure engineering offered by molecular beam epitaxy. THz QCLs can be based on different kinds of super-lattice structures such as GaAs/AlGaAs, InAs/AlSb and InGaAs/GaAsSb. The main challenge is to have the QCL lasing without the need of cryogenic cooling – a key factor for a variety of novel applications such as pollutant sensors, dynamic radar cruise control, medical diagnostics and infrared spectroscopy. While working at the National Research Council (NRC) and in collaboration with scientists from other institutions, Prof. Wasilewski developed a structure which lases in the 3 THz frequency at 200K. To date, this is the record maximum lasing temperature; but we are in the quest to beat it!

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It's a kind of energy called "electromagnetic (EM) radiation" (but this kind of radiation is not harmful, except for an occasional sunburn). There are other kinds of EM radiation too (radio waves, microwaves, x-rays, etc.), but light is the part WE can see, the part that makes the rainbow.

Change its direction by making it pass into another transparent material of different density, like glass or water. This is called REFRACTION, and it's how lenses work. There are actually other ways to bend or deflect light, including diffraction gratings and holographic lenses. Scientists have also found that gravity can bend light! View "Bending Light" demo from the University of Colorado Boulder

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About 186,000 miles per second [300,000 kilometers per second], so light from the sun takes about 8 minutes to go 93 million miles [149 million kilometers] to earth. Does this seem SLOW? Well, if you could DRIVE to the sun at 60 mph [100 kph], it would take you 177 years to get there! In one second, light can go around the earth 7 times!