Efficiently Controlling near-Field Wavefronts via Designer Metasurfaces

Freely tailoring the wavefronts of surface waves (SWs) plays a vital role in on-chip photonics applications, but diffraction-optics based devices usually exhibit limited tuning functionalities and low working efficiencies. Here, we propose a new strategy to manipulate the near-field wavefronts of SWs with Pancharatnam-Berry (PB) metasurfaces exhibiting predesigned phase profiles. As a SW beam flows across such a metasurface, waves scattered by different PB meta-atoms interfere with each other, forming a new SW wavefront under appropriate wavevector matching condition. As a proof of concept, we design and fabricate a series of PB metasurfaces working in the microwave regime and experimentally demonstrate that they can efficiently realize SW manipulations, including deflection, focusing, Bessel beam, and Airy beam generations. These findings may inspire the realization of highly miniaturized on-chip devices for integrated photonics applications.