High-directionality grating coupler-based optical antenna for chip-level LiDAR applications

This paper presents a high-directionality optical grating antenna for chip-level LiDAR applications. The antenna, designed on a silicon-nitride-nitride platform, consists of two vertically stacked grating layers with a nitride waveguide layer in between. By optimizing the grating periods, duty cycles, and the relative offset between the grating layers using a particle swarm optimization algorithm, a directionality of 87.8% (0.56 dB) at 1550 nm wavelength and a minimum coupling loss of 1.7 dB were achieved. The performance of the antenna was demonstrated in a chip-to-chip transceiver configuration using a coherent detection system. With a transmitter output power of 10 dBm, the system achieved a signal-to-noise ratio of 17.7 dB and 13.2 dB at screen distances of 20 m and 40 m, respectively. These results highlight the potential of the proposed antenna for long-range, chip-level LiDAR applications.