Zero modal birefringence

Vescent Photonics is developing a new generation of broadly tunable laser sources, under contract to the US National Institute of Standard and Technology.

Involvement of LioniX

For Vescent Photonics, LioniX designed and fabricated an optical slab waveguide which should show zero modal birefringence at roughly 450 nm. Therefore, the geometrical and material birefringence should completely compensate each other at that wavelength.

In the video, it is demonstrated that this is indeed possible. Here, both the TE- and the TM slab mode are exited by edge coupling, using a widely tunable dye laser. Above the waveguide, a polarizer is mounted, at 45 degrees with both TE and TM. As a consequence, the interference fringes of this polarimeter layout appear as a dark and bright "bands": the smaller the modal birefringence, the wider these bands. While sweeping the wavelength from green to blue, the birefringence clearly goes through zero. f

More information on www.vescentphotonics.com