Tunable multiband metamaterial coherent perfect absorber based on graphene and vanadium dioxide

In this paper, we propose a tunable multiband metamaterial coherent perfect absorber, where vanadium dioxide (VO 2 ) square particles are periodically arranged on the two sides of polysilicon–silica–graphene–silica–polysilicon​ structure. The absorption spectrum of our absorber exhibits three peaks with high absorptivity which are originated from the plasmon resonance modes of graphene and VO 2 particle. Benefitting from the tunable conductivity of graphene, the adjustment range of the absorption peak based on the first-order plasmon resonance mode of graphene is as much as 7 . 88 μ m when the Fermi level of graphene is increased from 0.3 to 1 eV. As VO 2 is changed from metal phase to insulating phase, the absorption peak stemming from the plasmon resonance mode of VO 2 particle disappears. The modulation depth of absorption peak can achieve up to 98.85% by tuning the relative phase of two coherent light beams . The resonance wavelengths and intensities of absorption peaks are also dependent on the array period, side length of VO 2 particle and the thickness of silica layer. In addition, the change of surrounding refractive index causes a shift of the absorption peak corresponding to VO 2 particle. Our findings are helpful for the engineering of actively tunable nano plasmonic devices and metamaterials. • We propose a tunable multiband coherent perfect absorber based on graphene and VO 2 . • The adjustment range of the absorption peak of graphene is as much as 7.88 μ m. • As VO 2 is changed from metal phase to insulating phase, the absorption peak of VO 2 particle disappears. • The modulation depth of absorption peak can achieve up to 98.85%.