Optical fabrication and characterisation of SU-8 disk photonic waveguide heterostructure cavities

In order to demonstrate cavity quantum electrodynamics using photonic crystal (PhC) cavities fabricated around self-assembled quantum dots (QDs), reliable spectral and spatial overlap between the cavity mode and the quantum dot is required. We present a method for using photoresist to optically fabricate heterostructure cavities in a PhC waveguide with a combined photolithography and micro-photoluminescence spectroscopy system. The system can identify single QDs with a spatial precision of ±25 nm, and we confirm the creation of high quality factor cavity modes deterministically placed with the same spatial precision. This method offers a promising route towards bright, on-chip single photon sources for quantum information applications

Strongly coupled single quantum dot in a photonic crystal waveguide cavity

Cavities embedded in photonic crystal waveguides offer a promising route towards large scale integration of coupled resonators for quantum electrodynamics applications. In this letter, we demonstrate a strongly coupled system formed by a single quantum dot and such a photonic crystal cavity. The resonance originating from the cavity is clearly identified from the photoluminescence mapping of the out-of-plane scattered signal along the photonic crystal waveguide. The quantum dot exciton is tuned towards the cavity mode by temperature control. A vacuum Rabi splitting of ~ 140 \mueV is observed at resonance.Comment: 11 pages, 3 figure

Ultrafast all-optical switching by single photons

An outstanding goal in quantum optics is the realization of fast optical non-linearities at the single-photon level. Such non-linearities would allow for the realization of optical devices with new functionalities such as a single-photon switch/transistor or a controlled-phase gate, which could form the basis of future quantum optical technologies. While non-linear optics effects at the single-emitter level have been demonstrated in different systems, including atoms coupled to Fabry-Perot or toroidal micro-cavities, super-conducting qubits in strip-line resonators or quantum dots (QDs) in nano-cavities, none of these experiments so far has demonstrated single-photon switching on ultrafast timescales. Here, we demonstrate that in a strongly coupled QD-cavity system the presence of a single photon on one of the fundamental polariton transitions can turn on light scattering on a transition from the first to the second Jaynes-Cummings manifold with a switching time of 20 ps. As an additional device application, we use this non-linearity to implement a single-photon pulse-correlator. Our QD-cavity system could form the building-block of future high-bandwidth photonic networks operating in the quantum regime

Photonic molecules defined by SU-8 photoresist strips on a photonic crystal waveguide

We present experimental and numerical investigations of photonic molecules obtained from laser patterned SU-8 photoresist strips on photonic crystal waveguides. Properties of cavities defined by a single strip are investigated and we show that two adjacent strips on a waveguide form a pair of optically coupled cavities. Simulation results and micro-photoluminescence mapping measurements demonstrate that the coupling strength is tunable by controlling the separation between the strips. Confocal mapping with decoupled collection and excitation points is used to explicitly show coupling between two cavities of a photonic molecule

Photonic molecules defined by SU-8 photoresist strips on a photonic crystal waveguide

We present experimental and numerical investigations of photonic molecules obtained from laser patterned SU-8 photoresist strips on photonic crystal waveguides. Properties of cavities defined by a single strip are investigated and we show that two adjacent strips on a waveguide form a pair of optically coupled cavities. Simulation results and micro-photoluminescence mapping measurements demonstrate that the coupling strength is tunable by controlling the separation between the strips. Confocal mapping with decoupled collection and excitation points is used to explicitly show coupling between two cavities of a photonic molecule

Cavity modes of tapered ZnO nanowires

We report on a cavity mode mapping of ZnO tapered nanowires using micro-photoluminescence spectroscopy at room temperature. Both the Fabry-Perot (FP) and the whispering gallery (WG) modes are identified in a single wire. The emission spectra from single nanowires comprise regular Lorentzian peaks, which arise from the FP interference between the ends of the nanowire. The overall intensity along the tapered wire varies periodically. This variation is ascribed to WG mode resonances across the nanowire. The results agree well with the theoretical calculations using the finite-difference time-domain method. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

Mapping cavity modes of ZnO nanobelts

ZnO nanostructures attract current interest because they have the potential to implement cavity quantum electrodynamics at room temperature. We report a photoluminescence mapping of ZnO nanobelts both at room temperature and 4.2 K. The multicavity modes were observed all over the belt surface, which were induced by Fabry-Ṕrot interference. The emission from the belt surface is enhanced at both the ends and the sides of the belt, and is highly linearly polarized in the direction perpendicular to the long axis of the belt. The results are explained using finite-difference time-domain simulations. © 2009 American Institute of Physics

Registration of single quantum dots for solid state cavity quantum electrodynamics

We discuss a novel technique to register the spatial and spectral characteristics of a single quantum dot using two photon absorption laser lithography. This would be useful in realizing solid state cavity quantum electrodynamics. © 2005 British Crown Copyright