Coherent line-beam LiDARs using polymer waveguide optical phased array

By incorporating a polymer waveguide optical phased array (OPA) device emitting a line beam output, we demonstrated a coherent detecting LiDAR system. The OPA comprises 128 polymer-waveguide phase modulators, providing efficient low-power phase modulation. A line-beam output was emitted from the end-fired waveguide array of the OPA, which was driven by a directly modulated DFB laser with a linear chirp rate of 83 THz/s. An iterative linearization process of the chirp was incorporated for the precise measurement of Doppler-induced beat frequencies produced by a moving target. Compared to the conventional raster-scanning method, the proposed line beam scanning method could reduce the acquisition time for a 4D point cloud. With the fabricated OPA chip exhibiting an insertion loss of 6.5 dB and a field of view of 30° × 32°, simultaneous detection of distance and velocity was demonstrated in order to distinguish between stationary and moving targets.