MEMS-based tunable Fabry-Perot filters on silicon substrates

A wavelength-tunable bandpass optical filter based on a Fabry-Perot cavity combined with a micro-actuator has been designed and fabricated, with an emphasis on achieving a wide tuning range. The measured tuning range of 1620 nm to 2425 nm is the largest reported for a MEMS-based Fabry-Perot filter, and is achieved by utilizing the strain stiffening effect in fixed-fixed beam actuators. This paper describes the optical design of the Fabry-Perot cavity, the mechanical design of the actuators, the fabrication process, and the measurement of both the device transmittance and the physical movement of the actuators. There is excellent agreement between the theoretical and measured transmittance of the filters when the small curvature in the top mirror of the Fabry-Perot cavity is accounted for.