Subwavelength Metal Grating Tunable Filter

This paper reports on the integration of subwavelength metal gratings with surface micro-machined, electrostatic MEMS actuators to produce a tunable electromagnetic filter. Metal films perforated with periodically-spaced subwavelength diameter holes have been shown to transmit light with greater efficiency than predicted by classical models for evanescent propagation. Additionally, the field propagation shows strong dependance on the index of refraction on either surface of the metal. This characteristic performance leads to electric field enhancement at the apertures in the metal, an effect that holds promise for nanoscale optical sensors. We describe our work on the integration of MEMS electrostatic actuators with patterned metal films that were interrogated using infrared (IR) radiation. We report a transmission modulation factor of 7 with an actuation voltage of 46V.