Extreme Metasurfaces Enable Targeted and Protected Wireless Energy Transfer

Abstract: Controlling the electromagnetic properties of materials beyond those achievable with natural substances has become a reality with the advent of metamaterials, artificially designed materials offering a wide range of unusual physical phenomena. The extreme properties that metamaterials provide can protect optical and electromagnetic systems from surrounding ordinary materials and substances - a feature never explicitly used yet. Wireless energy transfer, i.e., the transmission of electromagnetic energy without physical connectors, demands reliable and stable solutions for charging high-power systems like electric vehicles with no effect on people, animals, plants, etc. Here we tackle this challenging problem and suggest a novel approach of using metamaterials with extreme parameters to enable targeted and protected wireless energy transfer. We design and experimentally implement epsilon-near-zero (ENZ) and epsilon-and-mu-near-zero (EMNZ) metamaterials that provide an energy transmission if and only if both the transmitter and the receiver are equipped with these metamaterials. The fact of absence of materials with such extreme parameters protects the system against surrounding objects, which cause neither noticeable change in the system operation nor experience any detrimental effect. The system behind the proposed approach can be realised in virtually any frequency band by appropriate scaling and suitable choice of material. This technology will find applications in targeted wireless energy transfer systems, especially where high power is needed, including electric vehicles.