Dynamically\nSwitchable Mid-Infrared Perfect Absorber\nBased on Grating-Assisted Graphene Plasmon Excitation

Mid-infrared perfect absorbers (MPAs)\nunderpin numerous\ncutting-edge\ntechnologies; however, achieving substantial tunability with moderate\nvoltage at high speeds remains a significant challenge. Here, we propose\nand investigate a metal–insulator–metal structure-based\nMPA (MMPA), utilizing grating-assisted graphene plasmon excitation.\nOur device leverages an analogue of electromagnetically induced transparency\nto achieve dynamic modulation of the MMPA’s perfect absorption.\nThe MMPA achieves an impressive absorption modulation (98.1 to 34.7%)\nat 7.86 μm with a low driving voltage of 15 V. This modulation\nsurpasses existing graphene-based MPAs, which typically require much\nhigher voltages. Additionally, the MMPA exhibits a preliminary 3 dB\ncutoff frequency of 8.47 kHz, limited by the measurement method employed\nbut anticipated to reach a few GHz. This work demonstrates in-plane\ngrating-assisted coupling to a graphene plasmon and paves the way\nfor high-performance mid-infrared modulators, reconfigurable filters,\nand beam-steering metasurfaces.