▎ 摘　　要

Due to multimode coupling of the metal-grating assisted graphene plasmonic asymmetric system, multiple high-quality near-unity absorption enabling the quantitative manipulation, multiplexing function, high modulation efficiency and multi-functionalization of novel optical devices can be obtained. Since the spectral positions of the absorption peaks are with strong parabolic or linear relationship to the lower-layer graphene's chemical potential or the dielectric spacer's thickness, such system can be regarded as controllable modulators to realize electrically switchable effect, whose operation frequency can be tuned precisely over five discrete operation bandwidths. Excellent plasmonic switching is achieved, when a millimeter-level change of 0.0027 eV for the upper-layer graphene's chemical potential can result in an intensity change ratio of 73.7%. Otherwise, the maximum optical sensitivity and FOM factor for sensing the analyte refractive index can reach up to 38.675 THz/RIU and 584, respectively. Besides, the ultrahigh sensitivity (1321.5 nm/RIU) for sensing the environment also enables the temperature detection, and the solution limit can be as down as the absolute zero (-273.15 degrees C). Moreover, the polarization-adjustable and incident angle-insensitive properties (up to 75 degrees) further enhance the practicability and feasibility of the proposed system as sophisticated optoelectronic devices.