Thermo-Optic and Electric-Optic Dual-Channel Dynamically Switchable Terahertz Perfect Absorber

We theoretically demonstrate a thermo-optic and electric-optic dual-channel dynamically switchable terahertz (THz) absorber based on both bandwidth and intensity in a graphene-VO $_{\text {2}~}$ complex metamaterial. An ultra-broadband from 2.5 THz to 10.8 THz with near-unity absorption ( ${\geq }90$ %) is achieved when the ambient temperature ( $\boldsymbol {T}$ $_{\text {a}}$ ) is equal to ${}\,72{{ }^{\circ }\mathrm {C}}$ and the Fermi energy ( $ {E}$ $_{\text {F}}$ ) of graphene is zero and the absorption intensity decreases to less than 5% when ${T}$ $_{\text {a}}$ = ${}\,28{{ }^{\circ }\mathrm {C}}$ , accompanied by the sharply reduced bandwidth, verifying the superior thermo-optic modulation function. The absorption intensity is also artificially tuned from ~3.9% to ~99% in the 2.29-4.86 THz range by tuning the ${E}$ $_{\text {F}}$ from 0 to 0.9 eV, implying the remarkable electric-optic modulation behavior. Moreover, the designed absorber is independent on the polarization of incident light. The proposed absorber paves an effective avenue for its applications in intelligent absorbers, telecom and THz modulators, etc.