MZI

The laser, iris, and lenses must be aligned to the same optical axis. Ideally, the optical axis of these components should not change even if they are translated on the optical rail. A stage installed on the optical rail carrier allows for horizontal movement perpendicular to the direction of the rail.

Mach-Zehnder interferometers consist of a coherent light source like a laser, two beamsplitters, and two mirrors (Figure 1 and Figure 2). First, the light source is split into two paths using the first beamsplitter. The two beams each have the same optical path length, which is the distance traveled multiplied by the refractive index of the media they travel through. Each beam reflects off of a mirror and is recombined by the second beamsplitter. If there is a difference in the optical path lengths of the two beams that is less than the coherence length of the light source, interference fringes will be generated. Because the coherence length of a source can be extremely short, precision components and alignment are crucial. A sample can be measured by being placed in one of the beam paths. The resulting optical path length difference can be measured by observing the change in the interference fringes.

Each optical sub-assembly can be added to a table-top breadboard and easily slid along the optical axis via optical rails. The small linear motion stage placed on the carrier of the optical rail makes it easy to make fine adjustments in the optical axis direction or the orthogonal direction.

mach-zehnder modulator

Knowledge Center/ Application Notes/ Optomechanics Application Notes/ Building a Mach-Zehnder Interferometer

Mach-Zehnder interferometers are simple interferometric instruments that measure the relative phase shift between two collimated light beams. This phase shift can be used to determine small displacements, the transmitted wavefront error of transmissive optics, the refractive index of transparent materials, air flow in wind tunnels, and more.