Polysilicon Grating Switches for LiDAR

Abstract

Novel polysilicon grating switches are demonstrated, consisting of an optical grating suspended on a moving platform above a waveguide. Electrostatic attraction pulls the grating into close proximity to the waveguide, ejecting light out of the waveguide plane. The switches move only 0.9 to 1.4 $\mu \text{m}$ , and have MHz mechanical resonant frequencies, making them robust to mechanical vibration and shock. These switches enable a new mode of LiDAR imaging; by creating a focal plane array of switches, and coupling it with a standard camera lens, the LiDAR beam can be scanned across the scene with high speed and arbitrary pattern. Both time of flight and coherent ranging techniques are compatible with this approach. We have demonstrated a $10\times 10$ pixel array of these switches in a LiDAR system, collecting 3D raging data at up to 15 meters away and 5 frames per second, over a 1 degree field of view with 0.1 degree resolution. Additionally, we have shown the switches to be robust, efficient, and reliable, actuating at 15 Volts, with speeds faster than $4~\mu \text{s}$ , for over 9 billion cycles without degradation or failure. [2020-0132]