We design and analyse an ultra-thin metasurface consists of mono-layer all-dielectric fishnet structure. It is demonstrated that coherent perfect absorption (CPA) can be achieved in such a metasurface, and the coherent absorptivity is controllable by phase modulation. The angular selectivity of the metasurface shows the feasibility of CPA in oblique incidence circumstances, where the CPA frequency splits into two frequency bands for TE and TM polarizations. The CPA frequency of the metasurface can be manipulated by solely adjusting the thickness of the fishnet metasurface. Through rigorous numerical simulation, we show that the electromagnetic energy of two symmetrically propagating waves from both sides of the metasurface can be almost totally absorbed by the metasurface, and the coherent absorptivity can be flexibly modulated.
This work is supported by the Australian Research Council and the National Natural Science Foundation of China.