Broadband and high-efficiency ultrathin wavefront manipulation based on the Pancharatnam-Berry phase principle

A broadband and high-efficiency metasurface is proposed based on the Pancharatnam-Berry (PB) principle. The PB phase principle is analyzed using the scattering matrix approach and proposed to achieve the abrupt phase with an equal amplitude of the transmission coefficient. The abrupt phase φ has a linear relationship with the rotation angle θ, namely, φ=±2θ. A 1-D gradient metasurface was designed, and the circular polarized waves in the frequency range 8.2-10 GHz were refracted anomalously when left-handed circular polarization or right-handed circular polarization waves were irradiated vertically on the metasurface and the refraction angle of the circular polarized waves, depending on the chirality of the incident wave. Finally, a 2-D parabolic metasurface that not only converts planar circular polarized waves into spherical circular polarized waves, but also converges the parallel wave into a focus point, was designed. The focal distance of the 2-D parabolic metasurface decreases as the frequency of the incident wave decreases, and the half-maximum at full width shows the opposite trend.