Manipulation of the arbitrary scattering angle based on all-dielectric transmissive Pancharatnam Berry phase coding metasurfaces in the visible range.

In order to improve the transmitted efficiency of the metasurface in the visible range, an all-dielectric Pancharatnam-Berry phase unit structure was proposed. Using these Pancharatnam-Berry phase element particles with different rotation angles, all-dielectric encoding metasurfaces can be constructed. The encoding metasurface connects the physical coding particles with digital coding in digital signal processing. The manipulation of the continuous transmission angle requires the continuous change of the encoding metasurface period. Since the size of encoding particles on the coded metasurfaces cannot be designed to be infinitesimally small, it is impossible to obtain the continuously changing period of the coded metasurfaces. To manipulate effectively and freely the angle of scattering in the visible range, Fourier convolution principle in digital signal processing was introduced on all-dielectric encoding metasurfaces with Pancharatnam-Berry phase meta-atoms. The addition and subtraction operations on two initial encoding sequences can be implemented to obtain a new encoding sequence. The manipulation of the arbitrary scattering pattern after Fourier convolution operations on different encoding sequences can be realized, especially for larger abnormal deflection angles. The checkerboard encoding metasurface was also designed to further prove the applicability of the Fourier convolution principle. Moreover, by using the proposed all-dielectric highly efficient Pancharatnam-Berry phase encoding meta-atoms, these coded particles with different rotation angles can be precisely arranged to build the generators of the orbital angular momentum beam with different topological charges.