Multidimensional and multifunctional metasurface design using hybrid spin decoupling

Metasurfaces are nanometer-thick patterned interfaces that exhibit unprecedented control over the quintessential properties of light and provide a footing ground for many innovative optical effects and groundbreaking phenomena like metalenses, complex wavefront shaping, polarimetric sensing, etc. Often multifunctional metasurfaces enact a multitude of simultaneous functionalities by employing the photonic spin Hall effect (PSHE) that allows independent control of photons through spin-orbital interactions. However, the exhibited optical responses are locked to be opposite to each other, resulting in significant design complexities, cross-talk, and noise while adding more functionalities into a single device. Herein, we demonstrate multifunctional all-dielectric transmissive metasurfaces exploiting PSHE-based unique phase multiplexing as a generic designing method to provide independent control of orthogonal helicities, squeezing spin-dependent quad information channels with minimal observed noise and cross-talk. To authenticate the proposed concept, multifocal metalenses enabling spin-depended splitting in longitudinal and transverse directions are demonstrated, which generate two high-intensity focused spots under opposite handedness of the circularly polarized incidence and all four focus spots under the linearly polarized incidence of ultraviolet wavelengths. The proposed functional domain enhancement of metasurfaces with high-resolution phase modulation brings advances in compact multifunctional device design to the fields of microscopy, communication, data storage, imaging, etc.