Development of a Fourier-transform waveguide spectrometer for space applications

We describe the development of a waveguide Fourier-transform spectrometer for space-borne high-resolution sensing. A prototype device is designed to monitor the water vapor absorption band near 1,364 nm with a resolution of 0.05 nm. It has no moving parts and is based on a unique concept of arrayed interferometers implemented in silicon-on-insulator planar waveguide chip. The optical input is formed by many independent waveguides, providing a significantly increased light gathering capability (étendue) compared to single-waveguide input configurations. Enhancements of the spectrometer capabilities are achieved by stacking planar waveguide layers and by using surface gratings to couple light into the waveguides.