Single‐Photon Emission into Arbitrary Polarization States with Emitter Integrated Anisotropic Metasurfaces

Abstract The compact implementation of versatile polarization control for single‐photon emission is of vital importance in advanced optics and quantum photonics. However, the current design principles are restricted by poor choice of available polarization transformation, leading to limited control over the polarization of single‐photon emission. Here, on‐chip manipulation of single‐photon emission into arbitrary polarization states are proposed by integrating quantum emitters (QEs) with anisotropic metasurfaces. Holographic metasurfaces with segmented areas of anisotropic nano‐scatterers are employed to efficiently outcouple the QE‐excited surface plasmon polaritons, forming free‐space radiation consisting of two orthogonally linearly polarized components with completely and independently tailored phases and amplitudes. The latter enables single‐photon generation encoded with arbitrary polarization states, covering thereby the whole Poincaré sphere. Using nanodiamonds with germanium vacancy (GeV) color centers integrated with metasurfaces, room temperature experiments demonstrate the single‐photon generation of well‐collimated beams with circular, linear, and elliptical polarizations, characterized by high polarization purity (>94%) and small angular divergence (<2.5°). This work paves the way for versatile at‐source polarization control of on‐chip quantum emission, enabling diverse applications in quantum nanophotonics.