Liquid-crystal tunable optical phased array for LiDAR applications

Optical phased arrays (OPAs) with the ability of dynamic beam-steering hold great promise for LiDAR applications. In contrast to mechanical scanning, OPAs have the advantage of being capable of agile beam pointing, allowing the multifunctional operation in LiDARs. In this paper, we propose a liquid crystal (LC) tunable OPA to achieve 2D beam steering. This approach enables a LC-tunable beam control in a second axis in addition to an OPA-tuning, thereby achieving 2D beam steering at a single wavelength. The LC-tunable OPA is fabricated using a standard Si photonics process and a LC process common for commercialized LC displays and LC on Si (LCOS) devices. We have fabricated samples of LC-tunable devices and LC-tunable OPA devices for 1D and 2D steering respectively and demonstrated a LiDAR using the 1D steering device. By taking advantage of non-mechanical movement of the device, a target tracking is realized by detecting a person from a camera image and irradiating the steering beam in that direction with more than 10 frames per second. With a faster 2D steering, a 3D target tracking even for multiple targets could be realized in the future.