High-throughput deeply-etched scanning Michelson interferometer on-chip

A miniaturized scanning Michelson interferometer is demonstrated on-chip using a deep-etching process. Etching depths larger 300 μm were obtained with side-wall angle better than 0.1 degree and scalloping depth smaller than 60 nm. Multi-mode optical fibers with core diameters of 62.5 μm and 200 μm were used for delivering the white light to SOI chips with device layer heights of 90 μm and 200 μm for evaluating the improvement with larger depth. The resulting interferograms were compared showing 12-dB increase in the signal, which is a significant boost for the signal-to-noise ratio. The presented interferometer opens the door for the use of miniaturized instruments in practical applications.