Dual-band photodetector based on a large circular dichroism

Room temperature near-infrared photodetector has important applications in military, aerospace, and other fields. However, the development of highly efficient and highly selective circularly polarized photodetectors is still a challenge. Here, we theoretically demonstrate a near-infrared photodetector based on the dual-band perfect absorber in a filleted L-shaped chiral dielectric metal metasurface, and the optical, thermal, and electrical properties are analyzed in detail. Numerical simulation results show that two absorption peaks at λ=1129 nm and λ=1148 nm under right-hander circularly polarized (RCP) are achieved, and the absorption rate is both greater than 90%, while the electromagnetic waves are almost completely reflected under left-hander circularly polarized (LCP), which indicates that the proposed system has strong optical chirality. Then, we investigate the effects of polarization angle and structure period on the absorption spectra. The relationship between the surface temperature of the thermo-sensitive material and the wavelength is calculated when the absorber is used as the heat source. Finally, two kinds of chiral photodetectors based on different effects, thermoelectric and pyroelectric effects, are designed, and the temperature time-varying relationship of the thermo-sensitive material is mainly discussed at λ=1129 nm. By constructing a complete external circuit, the correlated electrical properties of the system to the load are analyzed. This integrated photothermoelectric numerical simulation method can comprehensively consider the optical, thermal, and electrical effects so as to more accurately predict the overall performance of the photo-detection system in practical applications, which can significantly improve the overall efficiency of the system and achieve better energy utilization and performance.