All-Silicon Multispot 2-D Beam Steering MEMS Mirror

Autonomous driving applications demand large Fields‑of‑View (FoV) and high scan rates from MEMS‑based LiDAR systems. To meet these requirements, a multispot system is proposed using a single beam source and a MEMS structure for simultaneous beam steering and splitting. The system integrates a MEMS scanner with a diffractive optical element, achieving a 86°H x 13°V FoV at a 20 Hz frame rate. The electrostatic MEMS mirror is based on a gimbal architecture, with a reflective surface relief Dammann grating (1550 nm wavelength targeted) on the mirror surface to split the incident beam into five equally distributed beams, increasing 5 times the probing field of view for the same vertical mechanical deflection. Vertically asymmetric electrodes actuate the inner axis (horizontal FoV) at resonance, while the outer axis (vertical FoV) was optimized for quasi‑static operation using staggered actuators. The device, fabricated on a 50 μm-thick SOI-wafer using a multilevel, self‑aligned, dicing‑free process, achieves an angular separation of the diffracted spots of 2.57°, with a beam uniformity of 68%. This work demonstrates a combined beam steering and beam splitting MEMS mirror to simultaneously increase the field of view and scan line resolution, motivating their integration in next-generation multispot LiDAR.