Single mode-fiber scale based square solid immersion metalens for single quantum emitters

Abstract In quantum networks, photons are used as flying qubits. The solid-state single quantum emitter based on the Diamond NV (Nitrogen-Vacancy) center exhibits good single-photon emission characteristics, which is the basis of a series of quantum technologies. Due to the high refractive index of the diamond, refraction and reflection at the material interface will hinder the collection of photons. Therefore, we designed a metalens formed by nano-scale rutile TiO2 pillar elements as an immersion lens to improve the collection efficiency of the deep diamond NV center at 700 nm, it is emphasized that the metalens is a technology that achieves light focusing beyond the diffraction limit through the surface micro-nano structure. This kind of structural design will be conducive to miniaturization of quantum devices and the development of single-photon-emitting metasurface based on fiber coupling.