Polarization Splitting Grating Coupler for Optical Antenna of LiDARs Consisting of Two Gratings Coupling Light in a Perfectly Vertical Direction

Grating couplers (GCs) are devices for transmitting and receiving the light propagated in a waveguide in silicon photonic integrated circuits (PICs). In this study, we propose a polarization splitting GC (PSGC) for the optical antenna of light detection and ranging (LiDAR). The PSGC was designed on the basis of two GCs coupling in a perfectly vertical direction. Our experiment demonstrated that the designed PSGC transmitted a polarization-multiplexed beam. The transmitting and receiving efficiencies of the optical antenna consists of lenses and PSGCs were calculated, and then the optical parameter for maximizing them was clarified.