Magnetic polariton enhanced broadband absorption and photoresponse of monolayer MoS2 based on normal and anomalous metallic gratings

Abstract

A novel structure of two-dimensional MoS2, with normal and anomalous metallic Ag grating, is proposed to enhance the broadband absorption of monolayer (ML) MoS2 and the photoresponse of MoS2-based photodetectors. The basic physical mechanism of both the normal and anomalous Ag grating with ML MoS2 is understood by studying the magnetic field distribution. The simulation results indicate that magnetic polaritons (MPs) with different orders could form different absorption peaks, and the same-order MPs with different groove heights can also form different absorption peaks, which can meet the expectations of achieving broadband adjustable absorption. Equivalent inductor capacitor circuit theoretical models are adopted to further verify the physical mechanism and resonance conditions of MPs in the structures of normal and anomalous metallic Ag gratings with ML MoS2, demonstrating that the theoretical calculations agree well with the simulation results. The effect of grating geometry for the absorption and photoresponse enhancement of ML MoS2-based photodetectors is also investigated, indicating that anomalous metallic gratings are more effective at achieving broadband absorption and an enhanced photoresponse of ML MoS2 compared with that of normal metallic gratings.