Biaxial Lissajous Scanning Piezoelectric MEMS Mirror Based on High Fill Factor and Large Optical Aperture

This paper reports a novel piezoelectric MEMS micromirror with high fill factor (19.6%) and large optical aperture (5 mm) based on CMOS-compatible Al(Sc)N. The 5 mm aperture can obtain a smaller laser divergence angle and achieve longer detection distance. Different from the gimbal-less micromirror which is prone to biaxial crosstalk, the double circular arc beam structure nested inside and outside can achieve high efficiency actuation and large scanning angle with low stress and low crosstalk. In vacuum, the mirror shows a biaxial scan angle of 52.5° (Horizontal, H) ×42.1° (Vertical, V) and reduce biaxial crosstalk by around 60% compared to previous work. Optical scanning angles of 21.8° at 816 Hz in the X-axis and 24.9° at 928 Hz in the Y-axis were initially achieved under air conditions. The figure of merit (FoM) of 0.502 is representing the leading level of piezoelectric micromirrors, which can meet the LiDAR (Light Detection and Ranging) system requirements.