Wavefront reversal (phase conjugation) using a MEMS spatial phase modulator (SPM) integrated with a metasurface retro-array: a proposal

Abstract

It is well-known that closed-loop deformable mirrors (DMs), liquid-crystal light valves, as well as MEMS SLMs, can compensate for piston errors. However, most aberrated beams additionally possess local tilt errors. Classes of MEMS-based SLMs exist that can provide "true wavefront reversal": tilt and piston error correction, but require three actuators to service each optical pixel, with tilt/piston-stroke tradeoffs. True wavefront reversal has also been demonstrated if a corner cube is attached to each piston element of a DM, which is not amenable to large arrays. We propose a compact MEMS-based SLM, augmented with a metasurface-based retroreflector array, providing true wavefront reversal (phase conjugation). Application to free-space optical (FSO) links, targeting, compensated imaging and long lasers will be described.