Optical fibre-based single photon source using InAsP quantum dot nanowires and gradient-index lens collection.

We present a compact, fibre-coupled single photon source using gradient-index (GRIN) lenses and an InAsP semiconductor quantum dot embedded within an InP photonic nanowire waveguide. A GRIN lens assembly is used to collect photons close to the tip of the nanowire, coupling the light immediately into a single mode optical fibre. The system provides a stable, high brightness source of fibre-coupled single photons.

Multiplexed Single-Photon Source Based on Multiple Quantum Dots Embedded within a Single Nanowire.

Photonics-based quantum information technologies require efficient, high emission rate sources of single photons. Position-controlled quantum dots embedded within a broadband nanowire waveguide provide a fully scalable route to fabricating highly efficient single-photon sources. However, emission rates for single-photon devices are limited by radiative recombination lifetimes.

Subwavelength grating periodic structures in silicon-on-insulator: a new type of microphotonic waveguide.

We report on the experimental demonstration and analysis of a new waveguide principle using subwavelength gratings. Unlike other periodic waveguides such as line-defects in a 2D photonic crystal lattice, a subwavelength grating waveguide confines the light as a conventional index-guided structure and does not exhibit optically resonant behaviour. Subwavelength grating waveguides in silicon-on-insulator are fabricated with a single etch step and allow for flexible control of the effective refractive index of the waveguide core simply by lithographic patterning.

Selective-area vapour-liquid-solid growth of InP nanowires.

A comparison is made between the conventional non-selective vapour-liquid-solid growth of InP nanowires and a novel selective-area growth process where the Au-seeded InP nanowires grow exclusively in the openings of a SiO(2) mask on an InP substrate. This new process allows the precise positioning and diameter control of the nanowires required for future advanced device fabrication. The growth temperature range is found to be extended for the selective-area growth technique due to removal of the competition between material incorporation at the Au/nanowire interface and the substrate.

Nanowire coupling to photonic crystal nanocavities for single photon sources.

We demonstrate highly efficient evanescent coupling via a silica loop-nanowire, to ultra-small (0.5 (lambda/n)(3) ), InAs/InP quantum dot photonic crystal cavities, specifically designed for single photon source applications. This coupling technique enables the tuning of both the Q-factor and the wavelength of the cavity mode independently, which is highly relevant for single photon source applications.