Recent progress in quantum nanophotonics brings novel ways for manipulating single photons in various nano-waveguides. Among them, one promising approach is to use optical nanofibres (ONFs), tapered optical fibres with sub-wavelength diameter waists. Here, we develop a hybrid system of an ONF and a single quantum dot (QD) operated at cryogenic temperatures. We deposit a single colloidal CdSe QD on an ONF waist and observe emitted photons through the fibre guided modes. We systematically investigate emission characteristics for both the neutral exciton and charged exciton (trion) for one specific QD. We quantitatively show that the trion at cryogenic temperatures acts as an excellent quantum emitter for the ONF and QD hybrid system. The present ONF/QD hybrid system at cryogenic temperatures paves the way for quantum information technologies for manipulating single photons in fibre networks.

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We demonstrate a bright and polarized fiber in-line single-photon source based on plasmon-enhanced emission of colloidal single quantum dots into an optical nanofiber. We show that emission properties of single quantum dots can be strongly enhanced in the presence of single gold nanorods leading to a bright and strongly polarized single-photon emission. The single photons are efficiently coupled to guided modes of the nanofiber and eventually to a single-mode optical fiber. The brightness (fiber-coupled photon count rate) of the single-photon source is estimated to be 12.2 ± 0.6 MHz, with high single-photon purity [g 2 (0) = 0.20 ± 0.04] and degree of polarization as high as 94-97 %. The polarized and fiber-coupled single photons can be implemented for potential applications in quantum photonics.

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We demonstrate a one-sided cavity on an optical nanofiber (ONF) using a composite method. The one-sided composite cavity is created by mounting an asymmetric defect mode grating on an ONF. We design the one-sided composite cavity on an ONF to enhance channeling efficiency into one side of ONF while operating from under-to critical-and over-coupling regimes using numerical simulations. Experimentally, we demonstrate coupling characteristics of the one-sided composite cavity, showing good correspondence with simulation results.

We investigate the emission characteristics of a single CdSe quantum dot on an optical nanofiber at cryogenic temperatures from the viewpoint of quantum photonics. We show that the charged exciton (trion) of the quantum dot is a promising quantum emitter for both aspects of spectral and temporal characteristics. The nanofiber/quantum-dot system may give a promising work bench for the future quantum photonic network.