High-Order Multifunctional Vortex Beam Generated by Pancharatnam-Berry Phase Coding Metasurfaces

We have designed a reflective ultra-wideband metasurface based on the Pancharatnam-Berry (PB) phase principle. This metasurface can work under the excitation of both circularly polarized waves and linearly polarized waves. Under the excitation of circularly polarized waves, this metasurface achieves a polarization conversion rate of over 80% in the frequency range of 7.6 GHz-13.5 GHz. By arranging the metasurface units in calculatedly phase distribution, we can achieve beam splitting, beam deflection, and orbital angular momentum (OAM) beam generation under the incident of circularly polarized waves. This allows for flexible control of circular polarized beams. Based on the phase superposition principle, vortex beam is compensated by phase focusing, which has a long propagation distance. By superimposing vortex beam with the beam splitting phase, multiple vortex beams can be generated. Under the incident of linearly polarized waves, different reflection amplitudes are obtained by changing the rotation angle of the metasurface unit. By arranging the metasurface units with different reflection amplitudes, we can achieve near-field imaging under the incident of linearly polarized waves. To improve the practical applicability of the metasurface in integrated optical devices, we combine phase and amplitude to construct the metasurface. This enhances the performance of the metasurface and improves its practical application.