Polarization characteristics of surface grating vertical cavity surface emitting laser

The polarization control of vertical cavity surface emitting laser (VCSEL) with surface grating structure was studied. After introducing the surface grating, the polarization-dependent mirror loss under different etching depths was simulated. The results show that the etching depth of the surface grating can achieve stable polarization in the range of 44 nm to 130 nm, which has a large fabrication tolerance. For the fundamental transverse mode, the orthogonal polarization suppression ratio (OPSR) of the surface grating VCSEL is more than 20 dB, and the peak-to-peak OPSR of the polarization-resolved spectrum reaches 40 dB. Effective polarization control can also be achieved even for multimode VCSEL. In order to further verify the effect of the grating on polarization control, two surface gratings with mutually perpendicular directions were fabricated. The OPSRs of the VCSEL with the two directional gratings were more than 20 dB. The test results show that surface grating is an effective means for VCSEL to achieve stable polarization.