Realization of broadband coherent perfect absorption of spoof surface plasmon polaritons

Abstract

In this work, we propose and demonstrate a scheme to realize broadband coherent perfect absorption of spoof surface plasmon polaritons (SPPs) using an ultrathin conductive film vertically placed on a plasmonic metasurface that supports spoof SPPs. When the conductive film possesses an appropriate sheet resistance, two incident coherent beams of spoof SPP waves can be simultaneously absorbed over a broad spectrum. By tuning the phase difference between the two incident beams from 0 to [Formula: see text], the absorption can be gradually changed from near-100% to near-zero, as verified in full-wave simulations and microwave experiments. Our work extends the theory of coherent perfect absorption from propagating waves to spoof SPPs with a significant advantage of broad working bandwidth.