Hybrid Integrated Silicon Nitride-Polymer Optical Phased Array For Efficient Light Detection and Ranging

Silicon nitride (SiN) optical phased arrays (OPAs) have emerged as a potential alternative to their silicon counterparts, owing to their low nonlinearity, easy scalability, and low propagation loss. However, the development of SiN OPAs for light detection and ranging (LiDAR) applications has attracted less attention due to the low thermo-optic (TO) effect of SiN. Moreover, SiN OPAs are considered to be undesirable for transmitters in LiDAR systems because of the limited longitudinal tuning efficiency of SiN grating antenna. We present a hybrid integrated SiN-polymer OPA for realizing an efficient LiDAR. Owing to the large TO effect of polymer, the proposed OPA with polymeric phase modulators resolves the power dissipation drawback of the SiN devices. The polymeric modulators are integrated with a SiN power splitter and grating antenna, and the coupling loss is alleviated via a spot-size converter. Additionally, a steering angle magnifying lens is used to enhance the tuning efficiency of the antenna, expanding the longitudinal beam steering range. The prepared OPA transmitter equipped with the lens exhibits decent two-dimensional beam steering, featuring stable emission characteristics over a 12° × 30° field of view. With the transmitter, efficient time-of-flight based LiDAR is demonstrated to provide a detection range of 10 m under a peak optical power of 55 dBm. The proposed SiN-polymer OPA is highly anticipated to circumvent the challenges of conventional SiN counterparts and potentially spearhead the development of a prominent OPA platform for advanced LiDAR schemes.