Dr James Christian's Outputs (118)

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.

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.

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.

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.

Helmholtz spatial solitons: towards a theory of ultranarrow optical beams (2012)
Presentation / Conference
Walsh, T., McDonald, G., & Christian, J. (2012, June). Helmholtz spatial solitons: towards a theory of ultranarrow optical beams. Poster presented at College of Science and Technology Research Showcase Day, University of Salford, Greater Manchester, UK

Spatial optical solitons are self-localizing and self-stabilizing beams of light that propagate with a stationary (invariant) intensity profile. Such nonlinear wave states may arise when a beam's natural tendency to diffract is exactly compensated by... Read More about Helmholtz spatial solitons: towards a theory of ultranarrow optical beams.

Spatiotemporal pulse propagation: connections to special relativity theory (2012)
Presentation / Conference
connections to special relativity theory. Poster presented at College of Science and Technology Research Showcase Day, University of Salford, Greater Manchester, UK

We propose a more complete model for describing the evolution of scalar optical pulses in nonlinear waveguides. The electromagnetic wave envelope u satisfies a dimensionless spatiotemporal governing equation that is of a fully-second-order form. Wit... Read More about Spatiotemporal pulse propagation: connections to special relativity theory.

Spatial solitons at interfaces: nonparaxial refraction & giant Goos-Hänchen shifts (2012)
Presentation / Conference
nonparaxial refraction & giant Goos-Hänchen shifts. Poster presented at College of Science and Technology Research Showcase Day, University of Salford, Greater Manchester, UK

The behaviour of light at interfaces underpins, in an essential way, the entire field of optics: almost all technological device designs and architectures rely on the interplay between material mismatches (that define the interface) and the 'degree o... Read More about Spatial solitons at interfaces: nonparaxial refraction & giant Goos-Hänchen shifts.

Helmholtz dark solitons: oblique propagation, saturable materials & bistability (2012)
Presentation / Conference
oblique propagation, saturable materials & bistability. Poster presented at College of Science and Technology Research Showcase Day, University of Salford, Greater Manchester, UK

Dark spatial optical solitons comprise a uniform background wave that is modulated by an obliquely-propagating 'dip' in the light intensity profile. Appearing throughout nonlinear science, these universal entities possess a phase topology that endows... Read More about Helmholtz dark solitons: oblique propagation, saturable materials & bistability.

Instabilities & boundary conditions: fractal mode patterns in kaleidoscope lasers (2012)
Presentation / Conference
fractal mode patterns in kaleidoscope lasers. Poster presented at College of Science and Technology Research Showcase Day, University of Salford, Greater Manchester, UK

The multi-scale - or fractal - nature of transverse modes in one-dimensional (1D) unstable cavity lasers has been known since the late 1990s [1]. Early collaborations with some members of our Group demonstrated that the origin of fractality (which de... Read More about Instabilities & boundary conditions: fractal mode patterns in kaleidoscope lasers.

Vector spatial solitons: off-axis nonparaxiality in coupled Helmholtz equations (2012)
Presentation / Conference
in coupled Helmholtz equations. Poster presented at College of Science and Technology Research Showcase Day, University of Salford, Greater Manchester, UK

Vector spatial solitons are complex optical beams with several distinct components. These components (which may be bright-like and/or dark-like) are localized in space and tend to overlap strongly in the propagation plane, thereby allowing the interp... Read More about Vector spatial solitons: off-axis nonparaxiality in coupled Helmholtz equations.

Two-colour optical fields: modulational instabilities and vector spatial solitons (2011)
Presentation / Conference
Bostock, C., Christian, J., & McDonald, G. (2011, November). Two-colour optical fields: modulational instabilities and vector spatial solitons. Presented at 2nd CSE Doctoral School Postgraduate Research Conference, University of Salford, Greater Manchester

The propagation of a light beam at a single optical frequency – or colour – in a Kerr-type planar waveguide is an elementary configuration in photonics [1,2]. Under two classic assumptions: (i) that the transverse extent of the
beam is much greater... Read More about Two-colour optical fields: modulational instabilities and vector spatial solitons.

Optical fractals: characterization, cavities, coherence and connections (2011)
Presentation / Conference
Mcdonald, G., Christian, J., Walsh, T., & Huang, J. (2011, September). Optical fractals: characterization, cavities, coherence and connections. Presented at 11th International Conference on Laser and Fiber Optics Networks Modeling, LFNM'2011, Kharkov, Ukraine

Uniform and regular systems can generate optical fractals. After characterizing different fractal-generating systems, emphasis is placed on the roles of boundary conditions and cavity feedback. New aspects of linear and nonlinear optical fractals are... Read More about Optical fractals: characterization, cavities, coherence and connections.

Pulses with relativistic and pseudo-relativistic aspirations (2011)
Presentation / Conference
Lundie, M., Lancaster, G., Hodgkinson, T., Christian, J., Mcdonald, G., & Chamorro-Posada, P. (2011, July). Pulses with relativistic and pseudo-relativistic aspirations. Presented at Waves 2011 - 10th International Conference on Mathematical and Numerical Aspects of Waves, Vancouver, Canada

Temporal solitons are robust self-localizing pulses that play a pivotal role in modern understandings of nonlinear wave phenomena. Here, we propose a new approach for describing pulses in dispersive nonlinear systems. By retaining the fuller generali... Read More about Pulses with relativistic and pseudo-relativistic aspirations.

Relativistic effects in non-relativistic systems (2011)
Presentation / Conference
McDonald, G., Christian, J., & Hodgkinson, T. (2011, June). Relativistic effects in non-relativistic systems. Poster presented at SEE Celebration of Research, University of Salford, Greater Manchester, UK

We propose a new model for describing the evolution of scalar optical pulses in Kerr-type planar waveguides and optical fibres. The wave envelope satisfies a dimensionless equation and its solutions are thus endowed with some intriguing and mystical... Read More about Relativistic effects in non-relativistic systems.

White light lasers (2011)
Presentation / Conference
Rose, C., McDonald, G., & Christian, J. (2011, June). White light lasers. Poster presented at SEE Celebration of Research, University of Salford, Greater Manchester, UK

Broadband multiline frequency combs present a wealth of applications, ranging from meteorology, sensing and measurements to those potentially in the domain of attosecond science. We report here on detailed investigations of a novel process that is ac... Read More about White light lasers.

Snell's law for nonlinear beams (2011)
Presentation / Conference
Christian, J., McDonald, G., Sanchez-Curto, J., & Chamorro-Posada, P. (2011, June). Snell's law for nonlinear beams. Poster presented at SEE Celebration of Research, University of Salford, Greater Manchester, UK

The refraction of plane waves at a uniform boundary between dissimilar linear dielectric materials is perhaps one of the oldest and best-understood phenomenon in optics. In contrast, the behaviour of a beam with a finite transverse cross-section is m... Read More about Snell's law for nonlinear beams.

Relativistic & pseudo-relativistic connections in optical pulse propagation (2011)
Presentation / Conference
Christian, J., McDonald, G., Lundie, M., & Lancaster, G. (2011, June). Relativistic & pseudo-relativistic connections in optical pulse propagation. Poster presented at College Research Showcase Day, University of Salford, Greater Manchester, UK

We explore a more complete model for describing the evolution of scalar optical pulses in generic nonlinear waveguides. The electromagnetic wave envelope satisfies a dimensionless equation that is of the Helmholtz type. Our
approach is to retain the... Read More about Relativistic & pseudo-relativistic connections in optical pulse propagation.

Propagation and stability of two-colour spatial optical solitons (2011)
Presentation / Conference
Bostock, C., Christian, J., & McDonald, G. (2011, June). Propagation and stability of two-colour spatial optical solitons. Presented at College Research Showcase Day, University of Salford, Greater Manchester, UK

Two-colour spatial solitons comprise coupled nonlinear optical beams at two distinct temporal frequencies [1]. The components (which may be bright-like and/or dark-like) are localized in space and tend to overlap, thereby allowing
the interplay betw... Read More about Propagation and stability of two-colour spatial optical solitons.

Cavity-enhanced broadband light generation (2011)
Presentation / Conference
Rose, C., McDonald, G., & Christian, J. (2011, June). Cavity-enhanced broadband light generation. Poster presented at College Research Showcase Day, University of Salford, Greater Manchester, UK

Broadband (multiline frequency) light combs present a wealth of applications, ranging from meteorology, sensing and measurements to those potentially in the domain of
attosecond science. We report here on detailed investigations of, what we believe... Read More about Cavity-enhanced broadband light generation.

Arbitrary-angle scattering of spatial solitons from dielectric optical interfaces (2011)
Presentation / Conference
McCoy, E., Christian, J., & McDonald, G. (2011, June). Arbitrary-angle scattering of spatial solitons from dielectric optical interfaces. Poster presented at College Research Showcase Day, University of Salford, Greater Manchester, UK

Wave–interface phenomena appear throughout Nature and are intrinsically angular in character. For instance, the behaviour of light waves at material boundaries underpins the entire field of optics. The seminal works on nonlinear
beam refraction [1]... Read More about Arbitrary-angle scattering of spatial solitons from dielectric optical interfaces.