Controllable coherent perfect absorber made of liquid metal-based metasurface

Coherent perfect absorber (CPA) is a novel strategy proposed and demonstrated for solving the challenge to attain efficient control of absorption by exploiting the inverse process of lasing. The operation condition of CPA results in narrow-band, which is the main limitation obstruct it from practical applications. Here, we demonstrate a CPA with tunable operation frequency employing the liquid metal made reconfigurable metasurface. The flow of liquid metal is restricted with a plastic pipe for realizing a controllable liquid metal cut-wire. The adjustable electric dipolar mode of the reconfigurable cur-wire metasurface ensures that the quasi-CPA point can be dynamically controlled; the measured CPA under proper phase modulation is in good agreement with the simulation results. The proposed CPA system involving liquid metal for dynamic control of operation frequency will have potential applications and may stimulate the exploitation of liquid based smart absorption control of optical waves.