Broadband and High-Resolution Mid-Infrared Spectroscopy Enabled by a Single Phase Change Metasurface

The mid-infrared (MIR) spectral region is crucial for various applications due to its unique properties, but traditional spectrometers are often bulky. Miniaturized spectrometers face a trade-off between spectral and spatial resolution. Here, a novel approach to MIR spectroscopy is numerically demonstrated by employing an electrically controlled phase-change metasurface. This method fully exploits the high optical contrast and the quasi-continuous phase change characteristics of chalcogenide phase change materials, enabling the construction of a set of spectral responses that provide broad spectral coverage with low correlation, utilizing a single metasurface pixel. With this innovative strategy, a broadband and high-resolution spectral reconstruction is numerically demonstrated with a full width at half maximum (FWHM) resolution of 20 nm and a dual-peak resolution of 160 nm within a 2400 nm bandwidth. Furthermore, the potential of the spectral detection scheme is underscored by the successful numerical reconstruction of the absorption peaks of methane and carbon dioxide, highlighting its capability for gas analysis and molecular identification. The integration of the spectral detection method into the field of spectral imaging is anticipated to have significant implications, suggesting substantial improvements in chemical process monitoring, and rapid diagnostic techniques in combustion environments.