Highly efficient wavefront control based on extremely anisotropic materials

In this paper, a new strategy to design phase gradient metasurfaces (PGMs) are proposed. Using this way, we can achieve highly efficient control of the electromagnetic wavefronts. Specifically, we design reflection-type PGMs formed by an extremely anisotropic medium and a perfect electric conductor boundary. Instead of using refractive index distributions of materials to control the phases, we use a uniform anisotropic medium to control the reflection phases by changing the shape of the boundary. Using this strategy, three devices of the reflection focusing lens, the generator of the quasi airy beam and the PGMs have been realized, which show excellent performance in wavefront control. Our method is also suitable for the design of transmission-type metasurfaces and other wavefront transformations, which provides a novel approach for wave manipulation.