Simultaneous Enhancement of Viewing Angle and Angular Resolution of Integrated Lidar with Bidirectional Signals and Orthogonal Polarizations

Coarse wavelength division multiplexing (CWDM) technology has been widely used in short-reach optical communication systems. By using the same technology in a solid-state photonics-based Lidar, one can achieve significant cost reduction. Beam steering is realized through diffraction of light wave upon grating couplers. However, current design has a small viewing angle and a low angular resolution. We propose a configuration based on Silicon-on-Insulator (SOI) waveguide grating coupler. The viewing angle is increased by 2.5 times with light signals propagating bidirectionally. The angular resolution is doubled through interleaving beams with trans-electrical (TE) polarization and beams with trans-magnetic (TM) polarization. By optimizing the design of a single grating coupler, the output beams are evenly distributed and the transmittance is improved. With 4 CWDM lasers being the source, a 34° beam angle of view and an angular resolution of 1.9° are demonstrated.