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.