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Proceedings Paper

Tunable Fabry-Pérot interferometer with subwavelength grating reflectors for MWIR microspectrometers
Author(s): Marco Meinig; Steffen Kurth; Mario Seifert; Karla Hiller; Julia Wecker; Martin Ebermann; Norbert Neumann; Thomas Gessner
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Paper Abstract

This report presents recent advances in the design and fabrication of a tunable Fabry-Pérot interferometer (FPI) with subwavelength grating (SWG) reflectors, as well as measurement results and applications. The FPI is designed as wavelength selecting element for highly miniaturized mid-wave infrared spectrometers. The optical resonator of the FPI is built between two highly reflecting mirrors. The mirrors are integrated in a supporting MEMS structure with one electrostatically movable and one fixed mirror carrier. The FPI is fabricated in a bulk micromachining batch process on wafer level from two silicon substrates. The substrates are bonded together with an intermediate SU-8 layer. The reflectors are made of aluminum subwavelength gratings, structured on a thin LP-Si3N4 membrane by nanoimprint lithography. The subwavelength structures build a frequency selective surface with high reflectance and low absorbance in a defined spectral range. Simulations and optimization of the design were done using finite element method with a 3D EM frequency domain solver. Comparison of simulation results and measurements of fabricated reflectors and FPIs are in very good agreement. The FPIs are used in the 5th interference order and can be tuned from 3.5 μm to 2.9 μm electrically. The measured maximum transmittance is between 70 % and 50 % and the measured FWHM bandwidth is lower than 50 nm. The new subwavelength grating reflectors can be integrated in a MEMS batch process more cost-efficient than previously used reflectors of dielectric layer stacks.

Paper Details

Date Published: 1 April 2016
PDF: 14 pages
Proc. SPIE 9759, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics IX, 97590W (1 April 2016); doi: 10.1117/12.2213647
Show Author Affiliations
Marco Meinig, Fraunhofer-Institut für Elektronische Nanosysteme (Germany)
Steffen Kurth, Fraunhofer-Institut für Elektronische Nanosysteme (Germany)
Mario Seifert, Technische Univ. Chemnitz (Germany)
Karla Hiller, Technische Univ. Chemnitz (Germany)
Julia Wecker, Technische Univ. Chemnitz (Germany)
Martin Ebermann, InfraTec GmbH (Germany)
Norbert Neumann, InfraTec GmbH (Germany)
Thomas Gessner, Fraunhofer-Institut für Elektronische Nanosysteme (Germany)
Technische Univ. Chemnitz (Germany)

Published in SPIE Proceedings Vol. 9759:
Advanced Fabrication Technologies for Micro/Nano Optics and Photonics IX
Georg von Freymann; Winston V. Schoenfeld; Raymond C. Rumpf, Editor(s)

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