Thermo-Optically Tunable Mid-Infrared Bandpass Filters Comprising Ultra-Thin Silicon-on-Sapphire Metasurfaces

Abstract

There is a need for high performance and compact mid-infrared hyperspectral imaging and spectroscopy systems for the reliable optical detection of chemical contaminants in environmental science, agriculture, heavy industry, and defense contexts. These applications are traditionally serviced by Fourier transform infrared (FTIR) spectrometers, but such systems are large, heavy, power hungry and of high cost. Tunable bandpass filters present a means to achieve mid-infrared spectrometers that are very compact, but previous approaches based on microelectromechanical systems are hindered by complex fabrication methods. Herein, how the thermo-optic effect can be exploited in zero-contrast grating (..