Dual-band perfect absorber for a mid-infrared photodetector based on a dielectric metal metasurface

Mid-infrared thermal detectors have very important applications in the aerospace and military fields. However, due to the low heat transfer efficiency and slow response time, their application has been greatly restricted. Here, we theoretically demonstrate a dual-band perfect absorber for a mid-infrared detector based on a dielectric metal metasurface, and the optical and thermal properties are analyzed in detail. Simulation results show that the two narrow absorption peaks, corresponding to the absorption value of 97.5% at lambda = 6.142 mu m with lambda(FWHM) approximate to 40 nm and 99.7% at lambda = 7.795 mu m with lambda(FWHM) approximate to 80 nm, respectively, are achieved, and their different dependences on the structural parameters have been studied. A thermal detector at room temperature with total response time within 1.3 ms for dual-band and 0.4 ms for single-band is realized when the incident light flux is 1.0 W/cm(2) for an average temperature increase of Delta T approximate to 1.0 K. Our study offers a promising approach for designing a narrowband mid-infrared perfect absorber and a high-performance photodetector in nano-integrated photonics. (C) 2020 Chinese Laser Press