Dr Graham McDonald's Outputs (169)

Relativistic and pseudorelativistic formulation of nonlinear envelope equations with spatiotemporal dispersion. I. Cubic-quintic systems (2018)
Journal Article

A generic envelope equation is proposed for describing the evolution of scalar pulses in systems with spatiotemporal dispersion and cubic-quintic nonlinearity. Our analysis has application, for instance, in waveguide optics where the physical origin... Read More about Relativistic and pseudorelativistic formulation of nonlinear envelope equations with spatiotemporal dispersion. I. Cubic-quintic systems.

Relativistic and pseudorelativistic formulation of nonlinear envelope equations with spatiotemporal dispersion. II. Saturable systems (2018)
Journal Article

We consider an envelope equation with space-time symmetry for describing scalar waves in systems with spatiotemporal dispersion and a generic saturable nonlinearity. Exact bright and gray solitons are derived by direct integration methods and coordin... Read More about Relativistic and pseudorelativistic formulation of nonlinear envelope equations with spatiotemporal dispersion. II. Saturable systems.

Spontaneous spatial fractal pattern formation in dispersive systems (2017)
Journal Article
Huang, J., Christian, J., & McDonald, G. (2017). Spontaneous spatial fractal pattern formation in dispersive systems. Journal of Nonlinear Optical Physics and Materials, 26(01), https://doi.org/10.1142/S0218863517500096

We report spontaneous spatial optical fractal patterns in a ring cavity containing a thin slice of diffusive Kerr-type material. The Turing threshold instability condition is derived through linear analysis, and static patterns are found to be descri... Read More about Spontaneous spatial fractal pattern formation in dispersive systems.

Vector dark solitons in systems with spatiotemporal dispersion and cubic nonlinearity : solutions and stability, transformations and relativity (2015)
Presentation / Conference
Carter, L., Christian, J., McDonald, G., & Chamorro-Posada, P. (2015, July). Vector dark solitons in systems with spatiotemporal dispersion and cubic nonlinearity : solutions and stability, transformations and relativity. Presented at 12th International Conference on the Mathematical and Numerical Aspects of Waves, Karlsruhe, Germany

The origin of conventional models for nonlinear optical pulse propagation lies in the ubiquitous slowly-varying envelope approximation (SVEA) accompanied by a Galilean boost to a local-time frame. While such a near-universal procedure typically resul... Read More about Vector dark solitons in systems with spatiotemporal dispersion and cubic nonlinearity : solutions and stability, transformations and relativity.

Nonlinear Helmholtz wave refraction & Goos-Hänchen shifts in nonparaxial optics : angles and interfaces, solitons and Snell's law (2015)
Presentation / Conference
McCoy, E., Christian, J., Sanchez-Curto, J., & McDonald, G. (2015, July). Nonlinear Helmholtz wave refraction & Goos-Hänchen shifts in nonparaxial optics : angles and interfaces, solitons and Snell's law. Presented at 12th International Conference on the Mathematical and Numerical Aspects of Waves, Karlsruhe, Germany

The interaction of self-localized waves with an abrupt interface is a problem of fundamental importance in many branches of physics, engineering, and applied mathematics. Waveguide optics, for instance, is dominated in an essential way by such consid... Read More about Nonlinear Helmholtz wave refraction & Goos-Hänchen shifts in nonparaxial optics : angles and interfaces, solitons and Snell's law.

Diffraction of Weierstrass scalar fractal waves by circular apertures : symmetry and patterns, complexity and dimension (2015)
Presentation / Conference
Christian, J., Woodroofe, E., & McDonald, G. (2015, July). Diffraction of Weierstrass scalar fractal waves by circular apertures : symmetry and patterns, complexity and dimension. Presented at 12th International Conference on the Mathematical and Numerical Aspects of Wave Propagation, Karlsruhe, Germany

The diffraction of plane waves from simple hard-edged apertures constitutes a class of boundary value problem that is well understood in optics, at least within the scalar approximation. Similarly, the diffraction of such waves from fractal apertures... Read More about Diffraction of Weierstrass scalar fractal waves by circular apertures : symmetry and patterns, complexity and dimension.

Unstable resonators with polygon and von Koch-type boundary conditions : virtual source modelling of fractal eigenmodes (2015)
Presentation / Conference
Christian, J., Begleris, I., Wickham, S., McDonald, G., & Huang, J. (2015, July). Unstable resonators with polygon and von Koch-type boundary conditions : virtual source modelling of fractal eigenmodes. Presented at 12th International Conference on the Mathematical and Numerical Aspects of Wave Propagation, Karlsruhe, Germany

We will report on our latest research into modelling fractal lasers (linear systems that involve geometrically-unstable resonators with inherent magnification), and propose two new classes of cavity configuration. These devices are of fundamental the... Read More about Unstable resonators with polygon and von Koch-type boundary conditions : virtual source modelling of fractal eigenmodes.

Multi-Turing instabilities & spontaneous patterns in discrete nonlinear systems : simplicity and complexity, cavities and counterpropagation (2015)
Presentation / Conference
Bostock, C., Christian, J., Leite, A., McDonald, G., & Huang, J. (2015, June). Multi-Turing instabilities & spontaneous patterns in discrete nonlinear systems : simplicity and complexity, cavities and counterpropagation. Presented at 12th International Conference on the Mathematical and Numerical Aspects of Wave Propagation, Karlsruhe, Germany

Alan Turing's profound insight into morphogenesis, published in 1952, has provided the cornerstone for understanding the origin of pattern and form in Nature. When the uniform states of a nonlinear reaction-diffusion system are sufficiently stressed,... Read More about Multi-Turing instabilities & spontaneous patterns in discrete nonlinear systems : simplicity and complexity, cavities and counterpropagation.

Diffraction of optical Weierstrass waves by simple apertures : circular symmetry and fractal dimension (2015)
Presentation / Conference
Christian, J., Woodroofe, E., & McDonald, G. (2015, June). Diffraction of optical Weierstrass waves by simple apertures : circular symmetry and fractal dimension. Presented at Conference on Lasers and Electro-optics Europe - European Quantum Electronics Conference 2015, Munich, Germany

On the asymptotic evolution of finite energy Airy wavefunctions (2015)
Journal Article
Chamorro-Posada, P., Sanchez-Curto, J., Aceves, A., & McDonald, G. (2015). On the asymptotic evolution of finite energy Airy wavefunctions. Optics Letters, 40(12), 2850-2853. https://doi.org/10.1364/OL.40.002850

In general, there is an inverse relation between the degree of localization of a wavefunction of a certain class and its transform representation dictated by the scaling property of the Fourier transform. We report that in the case of finite energy A... Read More about On the asymptotic evolution of finite energy Airy wavefunctions.

Helmholtz non-paraxial beam propagation method: An assessment (2014)
Journal Article
Chamorro-Posada, P., & McDonald, G. (2014). Helmholtz non-paraxial beam propagation method: An assessment. Journal of Nonlinear Optical Physics and Materials, 23(4), https://doi.org/10.1142/S0218863514500404

We present a performance evaluation of a non-paraxial beam propagation method suitable for the study of Helmholtz solitons. The analysis aims to determine the accuracy limits of the numerical scheme in terms of the maximum propagation angle addressab... Read More about Helmholtz non-paraxial beam propagation method: An assessment.

Single interfaces and coupled-waveguide arrays: off-axis nonparaxial analyses (2014)
Presentation / Conference
McCoy, E., Christian, J., McDonald, G., Sanchez-Curto, J., & Chamorro-Posada, P. (2014, September). Single interfaces and coupled-waveguide arrays: off-axis nonparaxial analyses. Presented at 5th European Optical Society Annual Meeting, Berlin, Germany

We report on our most recent results concerning arbitrary-angle spatial soliton
refraction at the interface between dissimilar dielectrics, each of which comprises
both X(3)and X(5) susceptibilities. Attention is also paid to the oblique injectio... Read More about Single interfaces and coupled-waveguide arrays: off-axis nonparaxial analyses.

Efficient parallel implementation of the nonparaxial beam propagation method (2014)
Journal Article
Sanchez-Curto, J., Chamorro-Posada, P., & McDonald, G. (2014). Efficient parallel implementation of the nonparaxial beam propagation method. Parallel Computing, 40(8), 394-407. https://doi.org/10.1016/j.parco.2014.06.003

An efficient parallel implementation of a nonparaxial beam propagation method for the numerical study of the nonlinear Helmholtz equation is presented. Our solution focuses on minimizing communication and computational demands of the method which are... Read More about Efficient parallel implementation of the nonparaxial beam propagation method.

Widely varying giant Goos–Hänchen shifts from airy beams at nonlinear interfaces (2014)
Journal Article
Chamorro-Posada, P., Sánchez-Curto, J., Aceves, A., & McDonald, G. (2014). Widely varying giant Goos–Hänchen shifts from airy beams at nonlinear interfaces. Optics Letters, 39(6), 1378-1381. https://doi.org/10.1364/OL.39.001378

We present a numerical study of the giant Goos–Hänchen shifts (GHSs) obtained from an Airy beam impinging on a nonlinear interface. To avoid any angular restriction associated with the paraxial approximation, the analysis is based on the nonlinear He... Read More about Widely varying giant Goos–Hänchen shifts from airy beams at nonlinear interfaces.

Gravitational theoretical development supporting MOND (2013)
Journal Article
Chadwick, E., Hodgkinson, T., & McDonald, G. (2013). Gravitational theoretical development supporting MOND. Physical Review D - Particles, Fields, Gravitation and Cosmology, 88(024036), https://doi.org/10.1103/PhysRevD.88.024036

Conformal geometry is considered within a general relativistic framework. An invariant distant for proper time is defined and a parallel displacement is applied in the distorted space-time, modifying Einstein’s equation appropriately. A particular so... Read More about Gravitational theoretical development supporting MOND.

The spatiotemporal ginzburg-landau equation: Dissipative solitons & stability (2013)
Presentation / Conference
Bresnahan, D., Christian, J., & McDonald, G. (2013, June). The spatiotemporal ginzburg-landau equation: Dissipative solitons & stability. Presented at College of Science & Technology Research Showcase, University of Salford

The complex Ginzburg-Landau (GL) equation describes universal wave propagation in dispersive systems that also exhibit competition between amplification and dissipation [1,2]. The balance between dispersive effects (group-velocity dispersion and self... Read More about The spatiotemporal ginzburg-landau equation: Dissipative solitons & stability.

Kaleidoscope lasers: Polygonal boundary conditions & geometrical instabilities (2013)
Presentation / Conference
McDonald, G., Christian, J., & Huang, J. (2013, June). Kaleidoscope lasers: Polygonal boundary conditions & geometrical instabilities. Presented at College of Science & Technology Research Showcase, University of Salford

Kaleidoscope lasers are geometrically unstable cavities with a feedback mirror that has the shape of a regular polygon [1]. Early calculations of the transverse eigenmodes of these systems hinted toward a fractal (or multi-scale) characteristic, but... Read More about Kaleidoscope lasers: Polygonal boundary conditions & geometrical instabilities.

Spontaneous spatial fractal patterns: Towards nonparaxial nonlinear ring cavities (2013)
Presentation / Conference
Bostock, C., Christian, J., & McDonald, G. (2013, June). Spontaneous spatial fractal patterns: Towards nonparaxial nonlinear ring cavities. Presented at College of Science & Technology Reserach Showcase, University of Salford

Spontaneous pattern formation in optical ring cavities containing a nonlinear (e.g., Kerr-type) material [see Fig. 1(a)] has been studied extensively for the past three decades. A notable trend in the literature over recent years has been a shift awa... Read More about Spontaneous spatial fractal patterns: Towards nonparaxial nonlinear ring cavities.

The absorptive ring cavity: Dynamics & patterns beyond the mean-field limit (2013)
Presentation / Conference
Readman, S., Christian, J., Bostock, C., & McDonald, G. (2013, June). The absorptive ring cavity: Dynamics & patterns beyond the mean-field limit. Presented at College of Science & Technology Research Showcase, University of Salford

An optical ring cavity filled with an absorptive material is a fundamental spontaneous pattern-forming system [1]. Analyses of Turing bifurcations in these (uni-directional) cavity configurations [see Fig. 1(a)] can be simplified by deploying the thi... Read More about The absorptive ring cavity: Dynamics & patterns beyond the mean-field limit.

The nonlinear fabry-pérot cavity: Complexity in a simple optical feedback system (2013)
Presentation / Conference
Patel, S., Christian, J., Bostock, C., & McDonald, G. (2013, June). The nonlinear fabry-pérot cavity: Complexity in a simple optical feedback system. Presented at College of Science & Technology Research Showcase, University of Salford

The nonlinear Fabry-Pérot (FP) cavity [see Fig. 1(a)] is a generalization of the classic diffusive Kerr slice with a single feedback mirror [1,2]. Such apparent simplicity is deceptive. Historically, analysis of the FP geometry has proved to be a non... Read More about The nonlinear fabry-pérot cavity: Complexity in a simple optical feedback system.