Development of High-Fill-Factor Large-Aperture Micromirrors for Agile Optical Phased Arrays

摘要

A new design of high-full-factor(HFF)micromirror array(MMA) has been proposed, fabricated and tested. Optical-phased-array (OPA) beam steering based on the HFF MMA has also been demonstrated. This unique HFF MMA design consists of large sub-apertures (i.e., mirror pixels). The flatness of the mirror surface is provided by a 80 micrometers-thick single-crystal silicon layer. The MMAs are fabricated using a single-wafer fabrication process without any wafer bonding, and the devices are surface-mountable right after the batch fabrication. A fabricated 4 4 MMA achieves a combined optical aperture of 6.4mm 6.4mm with approximately 90% fill factor and > 25 degree scan range in two axes at 4V DC. A static piston of 320 micrometers is achieved at less than 8V. The measured piston and rotation resonance modes are 247Hz and 320Hz, respectively. It is experimentally shown that the spot size from a rectangular aperture consisting of two consecutive sub-apertures is significantly reduced compared to that from a single sub-aperture when the phase difference between the two sub-apertures is electrically tuned to multiple 2pi.