On-chip spatial multiplexing metasurface for multi-channel optical field modulation

On-chip integrated metasurfaces driven by waveguides have excellent capabilities in optical field manipulation, enabling great significance in fields such as holographic display and optical communication. However, realizing the simultaneous modulation of both spatial and waveguide beams with a single metasurface remains challenging. Here, we proposed a metasurface modulation method based on the theories of the detour phase and Pancharatnam-Berry phase, which achieves simultaneous manipulation of waveguide radiation, polarization state, and dynamic wavefront from five incident optical channels. Moreover, to fully tap into the design potential of metasurfaces and avoid complex physical model inference, an end-to-end design framework was proposed to achieve joint optimization of design parameters and target light fields. As a prototype, we demonstrated three types of multi-channel silicon metasurfaces on Si₃N₄ waveguides, which realize the functions of holographic display, multi-focusing, and multi-channel vortex beam generation. The on-chip spatial multiplexing metasurface has the advantage of high integration and easy implementation, which has the potential to promote the development of multifunctional integrated optical systems.