High-responsivity dual-frequency hot-electron photodetectors with magnetic polaritons beneath metal grating strips

Abstract

Abstract In this work, near-infrared Au-grating/MoS2/Au hot-electron photodetectors (HEPDs) with magnetic polaritons (MPs) beneath the top Au grating strips are designed and proposed. The MPs are formed by the near-field coupling between the grating and the bottom Au film, which achieves a light absorption greater than 99.5% at 1550 nm for the HEPDs. The simulations show that the absorption wavelength can be tuned independently and widely to cover the whole short wavelength infrared band by adjusting width of the grating strips, and the near-perfect absorption characteristics can be maintained. Then, dual-frequency HEPDs with two different grating strip widths in one cycle of the Au-grating are designed. Without external bias, the theoretical responsivities as high as 11.2 mA W−1 at 1200 nm and 6.2 mA W−1 at 1550 nm are achieved for the HEPDs by a three-step electrical model. In addition, a modulation distance between the two absorption peak positions of the HEPDs could be larger than 1100 nm. This provides a new idea for the realization of high-responsivity near-infrared HEPDs for arbitrary dual-band detection, which has great potential in modern optical communication systems.