MEMS fourier transform spectrometer

Abstract

A comb actuated lamellar grating interferometer based MEMS Fourier Transform Infrared (FTIR) Spectrometer device is designed, fabricated and characterized. The device operates at out-of-plane resonant mode which will allow ultra miniaturized, sensitive, robust, and fast spectrometers. As a novel approach pantograph type springs are used in the mechanical design to achieve high deflections. The dynamic deformation on the gratings is minimized using additional suspension springs. Optical simulations are conducted to extensively analyze the device performance in terms of spectral resolution and signal-to-bias ratio (SBR). In the light of simulations and experiments, the grating geometry is optimized for the region of wavelengths of interest (2.5-16 μm). Comb structures are designed and placed around pantograph springs for low voltage operation. The fabrication process is developed based on CMOS compatible bulk micromachining of a silicon-on-insulator wafer. A maximum peak to peak mechanical deflection of 478 μm is acquired with 50 V p-p input voltage in ambient pressure.