Planar Light Valve and Displacement Phase Modulator: MEMS-based spatial light modulators for high-speed amplitude and phase modulation

We report on the development of high-speed 2D MEMS-based spatial light modulators for amplitude and phase modulation. The Planar Light Valve (PLV) and Displacement Phase Modulator (DPM) are 32×256-pixel arrays with programmable 7-bit control for modulation of UV to NIR wavelengths. With a frame rate of 250 kHz, PLV and DPM are targeted at laser applications requiring high switching speed, high power-handling and analog amplitude or phase control. We describe the primary technical challenges in developing these devices, including (a) materials selection and development, (b) MEMS process design, (c) MEMS electro-mechanics, and (d) CMOS driver design. For direct integration of MEMS on CMOS, we selected thermally compatible silicon–germanium. We describe how electromechanical finite element analysis was used to develop a CMOS driver with linearized displacement. We present preliminary test results on stroke, linearity, uniformity, efficiency, contrast, switching speed, and crosstalk. We show preliminary demonstrations of focusing and beam steering by phase modulation.