Large-Area MEMS Tunable Fabry-Perot Filters for Multi/Hyperspectral Infrared Imaging

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Abstract

This paper reports on a MEMS tunable Fabry-Perot filter technology capable of achieving nanometer-scale optical flatness across a large mirror area of up to square centimeters without any extraneous stress management techniques. The device employs a single-layer tensile silicon or germanium membrane for the suspended top mirror. Optical characterization of the fabricated single-membrane-based tunable filters for the SWIR, MWIR, and LWIR is presented. The fabricated 1000-μm dimension Si-membrane-based SWIR and MWIR filters are demonstrated with a wavelength tuning range of 1.77-2.42 and 4.1-4.9 μm, respectively, while the fabricated 200-μm-dimension Ge-membrane-based LWIR filter is demonstrated with a wavelength tuning range of 8.5-11.46 μm. All these filters are shown to achieve transmission characteristics that exceed the optical requirements for multispectral imaging applications. A large-area 1-cm dimension Si membrane-based SWIR tunable Fabry-Perot filter for multispectral imaging is demonstrated as a proof-of-concept, showing an excellent surface flatness in the order of 25 nm and an excellent optical uniformity with transmission peak wavelength variability less than 3% across the entire 1-cm dimension optical imaging area. In addition, the optical transmission behavior of the Fabry-Perot filters based on three-layer Si or Ge-based air-spaced DBRs for SWIR, MWIR, and LWIR is modeled, demonstrating that these filters can achieve a fine spectral resolution of several tens of nanometers suitable for hyperspectral imaging applications.

Original languageEnglish
Article number7795210
JournalIEEE Journal on Selected Topics in Quantum Electronics
Volume23
Issue number2
DOIs
Publication statusPublished - 1 Mar 2017

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