Compact Power-Efficient Optical Phased Array Enabled by Photonic Crystal Waveguide Phase Shifters

Optical phased arrays (OPAs) on a silicon chip enable non-mechanical beam steering and show promise for solid-state LiDAR, scanning imaging, and other applications. Thermo-optic phase shifters are widely used in such an OPA for low cost although they can consume much power. It is preferred to reduce the power consumption while maintaining compact sizes for phase shifters. In this work, we introduce a slow-light photonic crystal waveguide into the phase shifter, with a compact size of approximately $50~\mu $ m $\times 5~\mu $ m. By integrating an array of such phase shifters, we have developed a power-efficient silicon OPA. Its phase shift power consumption is 4 times lower than that of an OPA with conventional phase shifters, while realizing favorable beam steering over an angular range of 100°. The results pave a path forward to constructing power-efficient OPAs with a compact size.