Dynamically Switchable Mid-Infrared Perfect Absorber Based on Grating-Assisted Graphene Plasmon Excitation

Abstract

Mid-infrared perfect absorbers (MPAs) underpin numerous cutting-edge technologies; however, achieving substantial tunability with moderate voltage at high speeds remains a significant challenge. Here, we propose and investigate a metal-insulator-metal structure-based MPA (MMPA), utilizing grating-assisted graphene plasmon excitation. Our device leverages an analogue of electromagnetically induced transparency to achieve dynamic modulation of the MMPA's perfect absorption. The MMPA achieves an impressive absorption modulation (98.1 to 34.7%) at 7.86 mu m with a low driving voltage of 15 V. This modulation surpasses existing graphene-based MPAs, which typically require much higher voltages. Additionally, the MMPA exhibits a preliminary 3 dB cutoff frequency of 8.47 kHz, limited by the measurement method employed but anticipated to reach a few GHz. This work demonstrates in-plane grating-assisted coupling to a graphene plasmon and paves the way for high-performance mid-infrared modulators, reconfigurable filters, and beam-steering metasurfaces.