Polarization switching VCSEL (P-VCSEL)

Ziva Corporation in collaboration with UCSB will develop a directly modulated polarization switching laser based on the Vertical Cavity Surface Emitting Laser (VCSEL) geometry with a 3dB frequency of at least 10 GHz. This will be a major breakthrough in the ability to cost effectively fabricate directly modulated lasers (even in 2-D arrays) with polarization diversity which has hitherto been only possible by using expensive, bulky and lossy external modulators. The basic principle which we demonstrated in Phase I relies on the fact that the polarization of a diode laser optical output can be influenced by the direction of the current flow. As opposed to the horizontal geometry of a waveguide diode laser, the vertical VCSEL geometry makes it possible to inject pump current in two orthogonal directions. Two electrode pairs can be placed orthogonally around the cavity and the resulting orthogonal current directions can overcome the built-in asymmetry given by birefringence to actively control the polarization of the emitted laser light. We believe that this new class of device will be critical for laser-detection-and-ranging (LADAR) applications, and will open up a whole new class of devices and applications which exploit high speed polarization modulation.