Tunable Resonant‐Photopyroelectric Detector Using Chalcogenide−Metal−Fluoropolymer Nanograting

Abstract Pyroelectric detectors are often broadband and require external filters for wavelength‐specific applications. This paper reports a tunable, narrowband, and lightweight pyroelectric infrared detector built upon a flexible membrane of As₂S₃−Ag−P(VDF‐TrFE) with subwavelength grating, which is capable of both on‐chip filtering and photopyroelectric energy conversion. The top surface of this hybrid membrane is a corrugated As₂S₃−Ag film contributing to narrowband light absorption in the near‐infrared (NIR) regime, and the bottom part is a polyvinylidene fluoride‐trifluoroethylene (PVDF‐TrFE) membrane for the conversion of the absorbed light to an electrical signal. Uniquely, applying a bias voltage to the PVDF‐TrFE membrane enables the tuning of the device's absorption and pyroelectric characteristics owing to the piezoelectrically induced mechanical bending. The resonator exhibited a resonant absorption coefficient of 80% and a full‐width‐half‐maximum of 15 nm within the NIR, a responsivity of 1.4 mV mW⁻¹, and an equivalent noise power of 13 µW Hz^−1/2 at 1560 nm. By applying a 15‐V bias to the PVDF‐TrFE membrane, the absorption coefficient decreased to 18% due to the change in the grating period and incident angle. The narrowband and tunable features of the As₂S₃−Ag−P(VDF‐TrFE) pyroelectric detector will benefit a variety of potential applications in sensors, optical spectroscopy, and imaging.