Full-Channel Polarization-Multiplexed Structural Near-Field Excitations Using a Multiple-Phase-Assisted Metasurface

Surface waves (SWs), exhibiting local-field enhancement and subwavelength resolution, hold great promise for on-chip applications including communications, sensing/detection, integrated photonic circuits, and super-resolution imaging. While metasurfaces have offered unprecedented capabilities for exciting and manipulating SWs on the chip, existing meta-devices lack sufficient degrees of freedom to tailor SWs along multiple channels, which is unfavorable for optical integrations. Here, we introduce a strategy for designing helicity-modulated high-integration metasurfaces, which can generate structured SWs along four distinct channels. Our building-block meta-atoms, composed of multilayer metallic microstructures in transmission configuration, can exhibit tailored transmission phases governed by three distinct mechanisms, thereby enabling full control over four co/cross-polarization channels in the Jones matrix under illumination of two spin-polarized waves. To validate our concept, we numerically and experimentally demonstrate two high-integration metasurfaces operating in the microwave regime, which can generate four distinct directional SW beams and four distinct structured near-fields (including two deflected SW beams, one focused SW beam, and one SW Bessel beam). These findings provide a versatile and compact platform for integrated optics engineering and applications.