Polarization-independent multifunction applications based on perfect absorption in a simple graphene metasurface

The perfect absorption is realized in a simple graphene-based metasurface structure in the terahertz range. Tunability of the absorbance spectra in the proposed system is achieved thanks to the adjustable Fermi level of the graphene. The finite difference time domain (FDTD) and coupled model theory (CMT) methods are employed to analyze absorbance spectra. Then, the polarization-independent multifunction applications in the system are discussed. The maximal group index for slow-light effects is 40911, the maximal sensitivity for the sensing is 8886 nm/RIU, and the maximal modulation depth(MD) and the insertion loss(IL) for the on-off modulator are 99.14% and 0.0015 dB, respectively. The results may provide a way to design multifunction micro-nano optical devices.