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Dr James Christian's Outputs (152)

Bistable Helmholtz dark spatial optical solitons in materials with self-defocusing saturable nonlinearity (2017)
Journal Article
Christian, J., & Lundie, M. (2017). Bistable Helmholtz dark spatial optical solitons in materials with self-defocusing saturable nonlinearity. Journal of Nonlinear Optical Physics and Materials, 26(02), https://doi.org/10.1142/S0218863517500242

We present, to the best of our knowledge, the first exact dark spatial solitons of a nonlinear Helmholtz equation with a self-defocusing saturable refractive-index model. These solutions capture oblique (arbitrary-angle) propagation in both the forwa... Read More about Bistable Helmholtz dark spatial optical solitons in materials with self-defocusing saturable nonlinearity.

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.

Exact dipole solitary wave solution in metamaterials with higher-order dispersion (2016)
Journal Article
Min, X., Yang, R., Tian, J., Xue, W., & Christian, J. (2016). Exact dipole solitary wave solution in metamaterials with higher-order dispersion. Journal of Modern Optics, 63(Sup.3), 544-550. https://doi.org/10.1080/09500340.2016.1185178

We present an exact dipole solitary wave solution in a mutual modulation form of bright and dark
solitons for a higher-order nonlinear Schrödinger equation with third- and fourth-order dispersion
in metamaterials (MMs) using an ansatz method. Based... Read More about Exact dipole solitary wave solution in metamaterials with higher-order dispersion.

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.

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.

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.

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.

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.

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.

Diffraction of fractal light: New frontiers for the mathematics of edge waves (2013)
Presentation / Conference
Mylova, M., McDonald, G., & Christian, J. (2013, June). Diffraction of fractal light: New frontiers for the mathematics of edge waves. Presented at College of Science & Technology Research Showcase, University of Salford

The diffraction pattern produced by a plane wave (i.e., a perfectly uniform wavefront) scattering from an infinite hard edge is well-described by the Fresnel integral [1]. Such one-dimensional (1D) edge waves [see Fig. 1(a)] turn out to be truly elem... Read More about Diffraction of fractal light: New frontiers for the mathematics of edge waves.

Dark & anti-dark spatiotemporal solitons: From cubic to cubic-quintic systems (2013)
Presentation / Conference
Cowey, R., Christian, J. M., & McDonald, G. S. (2013, June). Dark & anti-dark spatiotemporal solitons: From cubic to cubic-quintic systems. Presented at College of Science & Technology Research Showcase, University of Salford, Greater Manchester M5 4WT, U.K

The origin of conventional models for optical pulse propagation lies in the universal slowly-varying envelope approximation (SVEA) accompanied by a Galilean boost to the local time frame. However, Biancalana and Creatore [1] have recently pointed out... Read More about Dark & anti-dark spatiotemporal solitons: From cubic to cubic-quintic systems.

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.

Coupled spatiotemporal waves: New paradigms in vector soliton physics (2013)
Presentation / Conference
Ashley, J. T., Christian, J., & McDonald, G. (2013, June). Coupled spatiotemporal waves: New paradigms in vector soliton physics. Presented at College of Science & Technology Research Showcase, University of Salford

In this presentation, we propose a novel spatiotemporal generalization of Menyuk’s classic equations [1] describing the propagation of two nonlinearly-coupled waves in a dispersive optical system (such as a fibre or planar waveguide). Our approach is... Read More about Coupled spatiotemporal waves: New paradigms in vector soliton physics.

Refraction at interfaces with X(5) nonlinearity: Snell’s law & Goos-Hänchen shifts (2013)
Presentation / Conference
McCoy, E., Christian, J., & McDonald, G. (2013, June). Refraction at interfaces with X(5) nonlinearity: Snell’s law & Goos-Hänchen shifts. Presented at College of Science & Technology Research Showcase, University of Salford

In this presentation, we give the first detailed overview of spatial soliton refraction at the planar interface between materials whose nonlinear polarization has contributions from both X(3)and X(5)susceptibilities [1]. The governing equation is of... Read More about Refraction at interfaces with X(5) nonlinearity: Snell’s law & Goos-Hänchen shifts.

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.

Coupled-waveguide arrays: Oblique injection & soliton propagation (2013)
Presentation / Conference
Christian, J., McCoy, E., & McDonald, G. (2013, June). Coupled-waveguide arrays: Oblique injection & soliton propagation. Presented at College of Science & Technology Research Showcase, University of Salford

The interaction between light beams and periodically-patterned host materials (such as coupled-waveguide arrays or photonic crystals) is a fundamental class of problem in nonlinear optics [1,2]. While oblique (off-axis) propagation effects play a cen... Read More about Coupled-waveguide arrays: Oblique injection & soliton propagation.

Ultrabroad-band Raman light: Linear detuning & gain suppression (2013)
Presentation / Conference
Kelly, R., Christian, J., & McDonald, G. (2013, June). Ultrabroad-band Raman light: Linear detuning & gain suppression. Presented at College of Science & Techology Research Showcase, University of Salford

Ultrabroad-band multifrequency Raman generation is a (laser-driven) resonant-symmetric two-colour pumping technique for exciting polychromatic light beams that are characterized by potentially very wide “top-hat” temporal bandwidths [1]. The spectra... Read More about Ultrabroad-band Raman light: Linear detuning & gain suppression.