Ultracompact single-photon sources of highly polarized vortex beams based on emitter coupled metasurface

Efficient integration of Quantum Emitters (QEs) with beam shaping and polarization encoding functionalities has always been on the agenda but heretofore remained elusive. Here, we proposed a general approach for designing chip-integrated single-photon sources with flexible control of photon polarization states and Orbital Angular Momenta (OAM), including the possibility for multichannel single-photon generation. The developed approach is based on meticulous design of QE-coupled anisotropic metasurfaces for outcoupling QE-excited diverging Surface Plasmon Polaritons (SPPs) into single-photon beams with desired properties. We have realized independent manipulation of the single photon Spin Angular Momentum (SAM) and OAM states by using anisotropic metasurfaces. Furthermore, we have demonstrated the generation of high-purity Linearly Polarized (LP) single-photon beams with arbitrary different OAMs and further extend to realize multiplexing of single-photon emission channels with orthogonal LPs carrying different topological charges. Our findings provide a promising approach for chip-scale control of quantum emission with versatile functionalities.