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arXiv · 2106.07093

Switchable induced-transmission filters enabled by vanadium dioxide

Abstract

Abstract: An induced-transmission filter (ITF) uses an ultrathin layer of metal positioned at an electric-field node within a dielectric thin-film bandpass filter to select one transmission band while suppressing other transmission bands that would have been present without the metal layer. Here, we introduce a switchable mid-infrared ITF where the metal film can be "switched on and off", enabling the modulation of the filter response from single-band to multiband. The switching is enabled by a deeply subwavelength film of vanadium dioxide (VO2), which undergoes a reversible insulator-to-metal phase transition. We designed and experimentally demonstrated an ITF that can switch between two states: one broad passband across the long-wave infrared (LWIR, 8 - 12 um) and one narrow passband at ~8.8 um. Our work generalizes the ITF -- previously a niche type of bandpass filter -- into a new class of tunable devices. Furthermore, our unique fabrication process -- which begins with thin-film VO2 on a suspended membrane -- enables the integration of VO2 into any thin-film assembly that is compatible with physical vapor deposition (PVD) processes, and is thus a new platform for realizing tunable thin-film filters.

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Chenghao Wan, David Woolf, Colin M. Hessel, Jad Salman, Yuzhe Xiao, Chunhui Yao, Albert Wright, Joel M. Hensley, Mikhail A. Kats. 2021-06-13. Switchable induced-transmission filters enabled by vanadium dioxide. https://doi.org/10.1021/acs.nanolett.1c02296

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