arXiv subjects

R. F. Oulton

Publications and source records attributed to R. F. Oulton.

3 recordsLinked to original sources

arXiv2011

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.

physics.optics↗

arXiv2004

Efficiency enhancement of organic based Light Emitting Diodes using a scattering layer

This paper presents an investigation of organic LED extraction efficiency enhancement using a low refractive index scattering layer. A scattering model is developed based on rigorous electromagnetic modelling techniques. The model accounts for proportions of scattered guided and radiation modes as well as the efficiencies with which emitted and scattered light are extracted. Constrained optimisation techniques are implemeneted for a single operation wavelength to maximise the extraction efficiency of a generic OLED device. Calculations show that a 2 fold efficiency enhancement is achievable with a correctly engineered scattering layer. The detailed analysis of the enhancement mechanism highlights ways in which this scheme could be improved.

physics.optics↗

arXiv2004

Optical coherence properties of planar microcavity emission

An analytical expression for the self coherence function of a microcavity and partially coherent source is derived from first principles in terms of the component self coherence functions. Excellent agreement between the model and experimental measurements of two Resonant Cavity LEDs (RCLEDs) is evident. The variation of coherence length as a function of numerical aperture is also described by the model. This is explained by a microcavity's angular sensitivity in filtering out statistical fluctuations of the underlying light source. It is further demonstrated that the variable coherence properties of planar microcavities can be designed by controlling the underlying coherences of microcavity and emitter whereby coherence lengths ranging over nearly an order of magnitude could be achieved.

physics.optics↗