Strongly enhanced local electromagnetic field in mid-infrared and terahertz photodetectors employing a hybrid antenna

A hybrid antenna consisting of a patch cavity and a metal grating is designed in this work. This antenna can effectively localize and enhance the intensity of the electric field inside a quantum well photodetector (QWP). The optical properties of the designed antenna are theoretically investigated, and it is found that the electric field can be increased by a factor of ∼104 in the infrared region (6–10 μm) and ∼105 in the terahertz (THz) region (100 μm). These enhancements can greatly improve the performance of QWPs. In the THz region, it is theoretically estimated that the hybrid antenna can increase the working temperature of the detector to 195 K, and the noise equivalent power is theoretically estimated to be as low as ∼10−18 W/Hz0.5 at T = 4 K and ∼10−15 W/Hz0.5 at room temperature, T = 300 K. These results are of great significance for applications of QWPs.