Directional off-Normal Photon Streaming from Hybrid Plasmon-Emitter Coupled Metasurfaces

Efficiently funneling photon streams from quantum emitters (QEs) in controllable directions is essential for interfacing the photon emission from nanoscale volumes with complex optical configurations exploited in quantum information and communication systems. We propose hybrid plasmon-QE coupled metasurfaces featuring circular nanoridges with displaced centers to funnel the photon emission along a given off-normal direction. The design principle relies on phase matching QE-excited circularly diverging surface plasmons to a well-collimated off-normal propagating photon stream by using a modified bullseye antenna with circular nanoridges having appropriately displaced centers. We demonstrate with the simulations that the hybrid plasmon-QE coupled metasurfaces enable highly directional off-normal photon emission with collection efficiencies exceeding 96%. Using nanodiamonds with multiple nitrogen vacancy centers, we experimentally demonstrate the directional photon streaming with different, up to 17.3°, off-normal angles and efficiencies reaching 90% for solid angles of <0.1 sr.