Simulation of superconducting single photon detector coupled with metal–insulator–metal concentric ring grating

Sub-wavelength metal–insulator–metal (MIM) concentric ring grating structure has been introduced to couple with superconducting single photon detector (SSPD) to enhance its response. The effects of the coupling structure parameters on the enhancement factor have been studied systematically. Our numerical simulation results show that the optical density arriving at the detection area of SSPD can be greatly enhanced by the structure of MIM concentric ring grating, corresponding to the improvement of detection response of the detector. A high enhancement factor more than 40 times can be obtained at wavelength of 1.55 μm with proper structure parameters.