White Light Interferometry of SOI Deeply-Etched Fully Integrated MEMS Interferometers

In this paper we investigate numerically and experimentally the effect of thin Silicon (Si) splitter

parasitic Fabry-Perot and Si/Air splitter Silicon dispersion on the white light interferometry of deeplyetched

MEMS interferometers using Silicon On Insulator (SOI) technology. The numerical simulations and

practical measurements show that multiple internal reflections inside the thin Silicon splitter form a

parasitic Fabry-Perot cavity inside the MEMS interferometer. This results in duplicated side interferograms

that practically limits the interferometer maximum optical path difference and hence the resolution of

MEMS based FT-IR spectrometer. Silicon dispersion, in case of Si/Air splitter results in a chirped and

shifted interferogram that can be compensated using very long travel range electrostatic MEMS actuators.

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