Hyperbolic Metamaterial Devices for Wavefront Manipulation

Metasurfaces have shown great potential to reshape the wavefront of electromagnetic (EM) waves, but transmissive meta‐devices face challenges of low‐efficiency and/or fabrication complexities. Here, an alternative approach to realize high‐efficiency transmission‐mode meta‐devices to control EM wavefronts, based on hyperbolic metamaterial (HMM) waveguides supporting tailored spoof surface plasmons (SSPs) on their side walls, is proposed. By manipulating the dispersions of SSPs through adjusting the HMM geometrical parameters, the phases of EM waves passing through such waveguides, which enables the design of meta‐devices with desired transmission‐phase profiles for particular wave‐manipulation applications, can be controlled. Microwave experiments are implemented to demonstrate two wave‐control effects based on the mechanism, that is, beam‐deflection and focusing, and a maximum conversion efficiency of 42.9% is achieved for the anomalous refracted beam. By scaling down the HMM meta‐devices, the proposal herein is applicable to optical frequencies and in principle promises significantly raised conversion efficiencies. The scheme herein can offer a higher effective refractive index and more tunable dispersion without using high‐index dielectric materials, and thus can serve as an effective and robust approach to make high‐efficiency transmissive meta‐devices with diversified functionalities. Hyperbolic metamaterial (HMM) meta‐devices are proposed to construct high‐efficiency transmissive metasurfaces for wavefront manipulation over the entire spectral regimes without the requirement of high‐index materials. HMM meta‐devices enable an anomalous refracted beam for linearly polarized and circularly polarized electromagnetic waves with conversion efficiencies of 42.9% in the microwave region and 77.9% in the near infrared region.