Digital coding THz dynamical multi-band perfect absorber via graphene/diamond metasurface

The monolayer graphene-based terahertz (THz) perfect absorber has made significant progress in switchable devices with diverse functionalities. However, the prior approaches to achieving switchability rely on either multi-layered metasurface with complex configuration or complicated patterned metasurface. A switchable absorber that uses tunable materials to switch between n-band and m-band modes is also intriguing but has not yet been reported. Here, a dynamically switchable multi-band perfect absorber with a digital coding graphene metasurface is proposed and demonstrated. By integrating multiple metasurface units with different Fermi levels into a newly generated period, we realize a multi-band perfect absorber with a rather simple and straightforward configuration composed of patterned metasurface. Through introducing a digital coding metasurface into the perfect absorber, we successfully use the digital signals from FPGA to convert n-band to m-band absorption modes. Moreover, the results reveal that the THz perfect absorber, possessing a great impedance matching with the free space, has excellent angle tolerance and robustness. Such a perfect absorber offers a flexible tool for selecting THz channels and may pave the way for the 6th generation communication.