We numerically demonstrate an optical waveguide structure for the coherent tunnelling adiabatic passage of photons. An alternative coupling scheme is used compared to earlier work. We show that a three rib optical waveguide structure is robust to material loss in the intermediate waveguide and variations to the waveguide parameters. We also present a five rib optical waveguide structure that represents a new class of octave spanning power divider.

Zinc oxide (ZnO) is a promising semiconductor that is suitable for bioimaging applications due to its intrinsic defect fluorescence. However, ZnO generally suffers from poor photostability. We report room‐temperature single‐photon emission from optical defects found in ZnO nanoparticles (NPs) formed by ion implantation followed by thermal oxidation in a silica substrate. We conduct a thorough investigation into the photophysics of a particularly bright defect and identify other single emitters within the NPs. Photostability was observed when the NPs were removed from the growth substrate and taken up by skin cells for in vitro imaging.

The emission rate of a radiating dipole within a nanoparticle is crucially dependent on its surrounding refractive index environment. In this manuscript, we present numerical results on how the emission rates are affected for nanoparticles in a homogenous and substrate environment. These results are general, applicable to any refractive index distribution and emitter.

Titanium dioxide is an emerging optical material, with a relatively high refractive index (n ∼ 2), which allows for high confinement of the electromagnetic field. Extensive research has been conducted on the negatively charged nitrogen vacancy centre in diamond due to its robust electronic and optical properties. In particular, its stable room-temperature photoluminescence properties have been considered for quantum optical applications. Nanobeam cavities are a geometry that offer exceptionally large-Q values given their minimal footprint, a must for high density and compact optical architecture. This paper presents an ultrahigh-Q nanobeam cavity within titanium dioxide in a low-refractive index environment operating at the negatively charged nitrogen vacancy centre of diamond. This research opens the possibility of hybrid optical devices utilising titanium dioxide and diamond.

We propose a high-Q photonic crystal cavity formed by introducing random disorder to the central region of an otherwise defect-free photonic crystal slab (PhC). Three-dimensional finite-difference time-domain simulations determine the frequency, quality factor, Q, and modal volume, V, of the localized modes formed by the disorder. Relatively large Purcell factors of 500–800 are calculated for these cavities, which can be achieved for a large range of degrees of disorders.