Active tunable MWIR filters: phase-change tunable filters for MWIR imaging based on GeSbTe-integrated metasurfaces

Abstract

The mid-wave infrared (MWIR) waveband (3-5 µm) contains numerous invaluable spectral /thermal signatures. Tunable MWIR filters are thus highly desirable in a variety of imaging and spectroscopic applications. We introduce phase-change tunable filters (PCTFs) which enable actively tunable spectral filtering across the MWIR waveband from a single solid-state element. This is achieved through the integration of the chalcogenide phase-change material GeSbTe (GST) into a plasmonic nanohole metasurface. We demonstrate polarization-insensitive PCTFs with >70% transmittance, 60nm bandwidth, and high-speed switching (MHz-GHz) across the MWIR waveband using a nanosecond laser pulse. We further show PCTF-based multispectral thermal imaging and dynamic gas sensing.