274 research outputs found
Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation
We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed
Anomalous spectral scaling of light emission rates in low dimensional metallic nanostructures
The strength of light emission near metallic nanostructures can scale
anomalously with frequency and dimensionality. We find that light-matter
interactions in plasmonic systems confined in two dimensions (e.g., near metal
nanowires) strengthen with decreasing frequency owing to strong mode
confinement away from the surface plasmon frequency. The anomalous scaling also
applies to the modulation speed of plasmonic light sources, including lasers,
with modulation bandwidths growing at lower carrier frequencies. This allows
developing optical devices that exhibit simultaneously femto-second response
times at the nano-meter scale, even at longer wavelengths into the mid IR,
limited only by non-local effects and reversible light-matter coupling
Tunable Indistinguishable Photons From Remote Quantum Dots
Single semiconductor quantum dots have been widely studied within devices
that can apply an electric field. In the most common system, the low energy
offset between the InGaAs quantum dot and the surrounding GaAs material limits
the magnitude of field that can be applied to tens of kVcm^-1, before carriers
tunnel out of the dot. The Stark shift experienced by the emission line is
typically 1 meV. We report that by embedding the quantum dots in a quantum well
heterostructure the vertical field that can be applied is increased by over an
order of magnitude whilst preserving the narrow linewidths, high internal
quantum efficiencies and familiar emission spectra. Individual dots can then be
continuously tuned to the same energy allowing for two-photon interference
between remote, independent, quantum dots
Clinical and cost effectiveness of a parent mediated intervention to reduce challenging behaviour in pre-schoolers with moderate to severe intellectual disability (EPICC-ID) study protocol: a multicentre, parallel-group randomised controlled trial
Background: Children with intellectual disabilities are likely to present with challenging behaviour. Parent mediated interventions have shown utility in influencing child behaviour, although there is a paucity of UK research into challenging behaviour interventions in this population. NICE guidelines favour Stepping Stones Triple P (SSTP) as a challenging behaviour intervention and this trial aims to evaluate its clinical and cost effectiveness in preschool children with moderate to severe intellectual disabilities. Methods: This trial launched in 2017 at four sites across England, with the aim of recruiting 258 participants (aged 30–59months). The Intervention Group receive nine weeks of SSTP parenting therapy (six group sessions and three individualised face to face or telephone sessions) in addition to Treatment as Usual, whilst the Treatment as Usual only group receive other available services in each location. Both study groups undergo the study measurements at baseline and at four and twelve months. Outcome measures include parent reports and structured observations of behaviour. Service use and health related quality of life data will also be collected to carry out a cost effectiveness and utility evaluation. Discussion: Findings from this study will inform policy regarding interventions for challenging behaviour in young children with moderate to severe intellectual disabilities. Trial registration number: Clinicaltrials.gov, NCT03086876. Registered 22nd March 2017, https://clinicaltrials.gov/ ct2/show/NCT03086876. Keywords: Intellectual disabilities, Challenging behaviour, Randomised control trial, Stepping stones triple P, SSTP, Parenting intervention
Hybrid plasmonic waveguide coupling of photons from a single molecule
We demonstrate the emission of photons from a single molecule into a hybrid gap plasmon waveguide. Crystals of anthracene, doped with dibenzoterrylene (DBT), are grown on top of the waveguides. We investigate a single DBT molecule coupled to the plasmonic region of one of the guides and determine its in-plane orientation, excited state lifetime, and saturation intensity. The molecule emits light into the guide, which is remotely out-coupled by a grating. The second-order autocorrelation and cross-correlation functions show that the emitter is a single molecule and that the light emerging from the grating comes from that molecule. The coupling efficiency is found to be βWG = 11.6(1.5)%. This type of structure is promising for building new functionality into quantum-photonic circuits, where localized regions of strong emitter-guide coupling can be interconnected by low-loss dielectric guides
Inequality, mobility and the financial accumulation process: A computational economic analysis
Our computational economic analysis investigates the relationship between inequality, mobility and the financial accumulation process. Extending the baseline model by Levy et al., we characterise the economic process trough stylised return structures generating alternative evolutions of income and wealth through historical time. First we explore the limited heuristic contribution of one and two factors models comprising one single stock (capital wealth) and one single flow factor (labour) as pure drivers of income and wealth generation and allocation over time. Then we introduce heuristic modes of taxation in line with the baseline approach. Our computational economic analysis corroborates that the financial accumulation process featuring compound returns plays a significant role as source of inequality, while institutional configurations including taxation play a significant role in framing and shaping the aggregate economic process that evolves over socioeconomic space and time
- …