Abstract: We have incorporated membrane mirror technology over a discrete array of pixel wells to create both high-efficiency optical shutters and spatial light modulators (SLM). A continuous metalized-membrane mirror with greater than 98% reflectivity minimizes optical insertion loss. This mirror is electrostatically deformed into the wells with either a common electrode (shutter) or pixilated electrodes (SLM). By using a spatial filter, analog intensity optical modulation is realized. Both 1-D (linear) and 2-D grating pixel patterns have been investigated. With the appropriate pixel dimensions, both coherent monochromatic and broadband incoherent light within the 0.25 to 10.6 micron range can be modulated with contrast ratios up to 1000:1. Small well sizes (approximately 10-micron diameter) allow for modulation speeds up to 1 MHz.

The theoretical foundations for the well layout, the membrane mirror deformation and its diffraction properties, and the design trade-offs are detailed. We have applied our membrane mirror technology to CMOS VLSI circuits creating a high-speed, high efficiency spatial light modulator capable of 80x64 resolution and scalable to HDTV standards. The membrane mirror SLM provides either amplitude or phase modulation. In the phase modulation mode, at least two waves of stroke per discrete well are possible.