Characterization of GaAs-based micro-origami mirrors by optical actuation

We have performed optical actuation to characterize GaAs-based micro-mirrors fabricated by the micro-origami technique. Micro-origami makes use of the energy stored as strain between lattice-mismatched semiconductor epitaxial layers to create self-positioning, three-dimensional structures with simple and robust hinges. Mirrors studied in this work were GaAs plates grown on In 0.22 Ga 0.78 As/GaAs strained layers. Optical actuation was achieved by uniformly shining the 488-nm line of a high-power Ar + laser on the mirrors. The laser light was either continuous wave (CW) or chopped with an acousto-optical modulator. Under a CW illumination of about 450 mW/mm 2 , an angular deflection of the mirror of 0.5° was obtained. When actuated with modulated light, the first resonant mode of the mirror was experimentally detected at 25 kHz. Finite element analysis showed that the experimental results correspond to a longitudinal-bending resonant mode of the mirror.