Tunable multichannel terahertz perfect graphene absorber with Fibonacci quasiperiodic photonic crystal

Tunable multichannel perfect absorption in monolayer graphene at terahertz frequencies is studied, which is realized through depositing a graphene monolayer on a Fibonacci quasiperiodic multilayer structure separated by a spacer. Three absorption peaks with absorptivity larger than 95% are obtained, which is attributed to the graphene Tamm plasmon polaritons and multiple photonic stopbands of dielectric Fibonacci multilayers. And the distributions of the electric field intensity are investigated to reveal the physical origin. Besides, the multichannel operating frequencies can be flexibly tuned through varying the angle of incidence and structure dimensions of the absorber, and it is found the absorption is not sensitive to the polarization state. In addition, the multichannel perfect absorption could be tuned to different frequencies through merely a change in the Fermi energy and the absorption performance could be flexibly extended to various channels of different number without re-optimizing the structure dimensions. We believe that the conclusions may find significant applications for the realization of novel tunable optoelectronic devices.