Optical design considerations in substrate-air-membrane micromechanical modulators

Summary form only given. We present a new design for nonsubstrate-contacting WDM micromechanical modulators, the phase-mismatched Fabry-Perot cavity. Micromechanical modulators in which a variable air gap forms the cavity between two mirrors, thus producing a Fabry-Perot optical device, have been explored for some time. Typically, the mirrors are multilayer, thus having reflectivities and producing cavities with high finesse. However, as we show here, Fabry-Perot devices can be designed with just a single-layer membrane suspended over a substrate that, therefore, have the same wide manufacturing tolerances and low finesse (and thus broad spectral bandwidth) as the MARS device. The noncontacting substrate-air-membrane micromechanical modulator improves upon the basic MARS by allowing a larger range of refractive indices to be used for the membrane.