Novel Wavefront-Splitting Interferometer for Ultra-Compact Broadband FT-IR Spectroscopy Extending to Visible Range

While MEMS interferometers reported so far rely on amplitude-splitting, this paper reports the first wavefront-splitting MEMS interferometer. The interferometer is ultra-compact and is part of a Fourier transform (FT) spectrometer fabricated using Deep Reactive Ion Etching (DRIE) of Silicon-on-Insulator (SOI). It enables the extension of the spectral range from Infrared to the visible range as validated from the experiments. The proposed interferometer architecture is based on spatial splitting and combination of optical beams using wavefront-splitting, where free-space propagation is only through air.