MEMS FTIR spectrometer with enhanced resolution for low cost gas sensing in the NIR

Abstract

In this work, we report the detection of C<inf>2</inf>H<inf>2</inf> and CO<inf>2</inf> in the NIR range using a MEMS Fourier Transform Infrared (FTIR) spectrometer. For this purpose, a super resolution autoregressive (AR) algorithm is used. The spectrometer is working in the wavelength range 1300-2500 nm while its core engine is a scanning Michelson interferometer micromachined using deep reactive ion etching (DRIE) technology on SOI wafer. The interferometer scanning mirror is driven by a MEMS electrostatic actuator with travel range corresponding to a resolution of about 30 cm^-1.The spectrometer with the algorithm are used for measuring a standard optical filter with line width of 1 nm and measured line width is 1.7 nm that corresponds to 7.5 cm^-1. The spectrum of a mixture of C<inf>2</inf>H<inf>2</inf> and CO<inf>2</inf> is measured using the MEMS spectrometer and a gas cell with 10cm light-gas interaction length. The AR model is applied on the interferogram. The resulting spectrum after the AR application shows an enhanced resolution of 15cm^-1 that led to better identification of the absorption peaks.