Chalcogenide Metasurfaces Enabling Ultra‐Wideband Detectors From Visible to Mid‐infrared

Thermoelectric materials can be designed to support optical resonances across multiple spectral ranges to enable ultra‐wideband photodetection. For instance, antimony telluride (Sb₂Te₃) chalcogenide exhibits interband plasmonic resonances in the visible range and Mie resonances in the mid‐infrared (mid‐IR) range, while simultaneously possessing large thermoelectric Seebeck coefficients of 178 µV K⁻¹. However, chalcogenide metasurfaces for achieving miniaturized and wavelength‐sensitive ultra‐wideband detectors have not been explored so far, especially with a single material platform. In this paper, Sb₂Te₃ metasurface devices are designed and fabricated to achieve ≈97% resonant absorption for enabling photodetectors operating across an ultra‐wideband spectrum, from visible to mid‐IR. Furthermore, relying on linear polarization‐sensitive Sb₂Te₃ metasurface, the thermoelectric photodetectors with linear polarization‐selectivity are demonstrated. This work provides a potential platform toward the portable ultrawide band spectrometers without requiring cryogenic cooling, for environmental sensing applications.