Photoconductive optically driven deformable membrane under high-frequency bias: fabrication, characterization, and modeling

Abstract

The fabrication and characterization of an optically addressable deformable mirror for a spatial light modulator are described. Device operation utilizes an electrostatically driven pixelated aluminized polymeric membrane mirror supported above an optically controlled photoconductive GaAs substrate. A 5 mum thick grid of patterned photoresist supports the 2 mum thick aluminized Mylar membrane. A conductive ZnO layer is placed on the backside of the GaAs wafer. Similar devices were also fabricated with InP. A standard Michelson interferometer is used to measure mirror deformation data as a function of illumination, applied voltage, and frequency. The device operates as an impedance distribution between two cascaded impedances of deformable membrane substrate, substrate, and electrode. An analysis of device's operation under several bias conditions, which relates membrane deformation to operating parameters, is presented.

All optically driven MEMS deformable device via a photodetector array

“…Fig. 2 shows our experimental arrangement; it is essentially the same setup used in our earlier work [7] except that the external photodetector, rather than the MEMS device, is illuminated by the optical control beam. The optical drive was provided by laser diodes operating at 830 nm and 980 nm, or by a helium-neon laser.…”

All optically driven MEMS deformable mirrors via direct cascading with wafer bonded GaAs/GaP PIN photodetectors

“…In earlier work [1,2] low stress Si 3 N 4 (Silicon Nitride) spring plate mirrors for such applications were successfully demonstrated. Future applications demand optically as well as individually addressable arrays of such mirrors.…”

MEMS-based optical limiter

“…Illuminating the device from the back side, changes the photoconductivity across the substrate and consequently the voltage drop across the membrane and substrate, which leads to membrane deflection. The membrane deflects in a parabolic form and the deflection is proportional to the square of the applied field Several operating mechanisms of this device have been described before 11,12,13 . These include:…”