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Dr James Christian's Outputs (118)

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.

Refraction law for self-collimated light beams at material interfaces (2010)
Presentation / Conference
McCoy, E., Christian, J., McDonald, G., Sanchez-Curto, J., & Chamorro-Posada, P. (2010, November). Refraction law for self-collimated light beams at material interfaces. Presented at 1st CSE Doctoral School Postgraduate Research Conference, University of Salford, Greater Manchester, UK

Perhaps the most fundamental electromagnetic phenomenon is the behaviour of light at the interface between dissimilar materials. In fact, the entire field of Optics follows from this single key concept. The reflection and refraction properties of a p... Read More about Refraction law for self-collimated light beams at material interfaces.

Refraction of power-law spatial solitons – the Helmholtz-Snell law (2010)
Presentation / Conference
Christian, J., Sánchez-Curto, J., Chamorro-Posada, P., McDonald, G., & McCoy, E. (2010, September). Refraction of power-law spatial solitons – the Helmholtz-Snell law. Presented at 10th International Conference on Laser and Fiber-Optical Networks Modeling (LFNM), 2010, Sevastopol, Crimea, Ukraine

The behaviour of a scalar optical beam at the boundary between two dissimilar nonlinear media is of fundamental interest in nonlinear photonics. Here, we report the first systematic generalization of our Kerr analyses to a wider class of power-law ma... Read More about Refraction of power-law spatial solitons – the Helmholtz-Snell law.

Kaleidoscope laser properties and new optical fractal contexts (2010)
Presentation / Conference
Christian, J., McDonald, G., Heyes, A., & Huang, J. (2010, September). Kaleidoscope laser properties and new optical fractal contexts. Presented at 5th International Conference on Advanced Optoelectronics & Lasers, CAOL 2010, Sevastopol, Crimea, Ukraine

We present the first detailed account of kaleidoscope laser modes where the equivalent Fresnel number Neq and magnification M may assume arbitrary values. Properties of these linear fractal eigenmodes are explored through extensive numerical computat... Read More about Kaleidoscope laser properties and new optical fractal contexts.

Universal Snell’s law & bright spatial soliton refraction (2010)
Presentation / Conference
Sánchez-Curto, J., Chamorro-Posada, P., Christian, J., McDonald, G., & McCoy, E. (2010, August). Universal Snell’s law & bright spatial soliton refraction. Poster presented at National Photonics Conference, Photon 10, Southampton, UK

The behaviour of a scalar optical beam at the boundary between two dissimilar Kerr media is of fundamental interest in nonlinear photonics. Since this class of problem is intrinsically nonparaxial, the limitations of conventional (paraxial) theory mu... Read More about Universal Snell’s law & bright spatial soliton refraction.

Optical pulses with spatial dispersion – solitons & relativity (2010)
Presentation / Conference
Christian, J., McDonald, G., Hodgkinson, T., & Chamorro-Posada, P. (2010, August). Optical pulses with spatial dispersion – solitons & relativity. Poster presented at National Photonics Conference, Photon 10, Southampton, UK

We propose a new model for describing the evolution of scalar optical pulses in Kerr-type waveguides. The (normalized) wave envelope u satisfies a governing equation that is of the nonlinear Helmholtz type, where the space and time coordinates are de... Read More about Optical pulses with spatial dispersion – solitons & relativity.

Fractal laser sources: new analyses, results and contexts (2010)
Presentation / Conference
Christian, J., McDonald, G., Heyes, A., & Huang, J. (2010, August). Fractal laser sources: new analyses, results and contexts. Presented at National Photonics Conference, Photon 10, Southampton, UK

A series of significant new extensions concerning fractal light generation are reported. Firstly, we summarise techniques and results from the first full analysis of the linear modes of ‘fractal lasers’ [1] – unstable-cavity geometries with arbitrary... Read More about Fractal laser sources: new analyses, results and contexts.

Novel cavity effects in ultra-broadband multiline Raman generation (2010)
Presentation / Conference
Rose, C., McDonald, G., & Christian, J. (2010, August). Novel cavity effects in ultra-broadband multiline Raman generation. Poster presented at National Photonics Conference, Photon 10, Southampton, 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, what we believe is, a nov... Read More about Novel cavity effects in ultra-broadband multiline Raman generation.

Kaleidoscope lasers - Complexity in simple optical systems (2010)
Presentation / Conference
Christian, J., McDonald, G., & Huang, J. (2010, June). Kaleidoscope lasers - Complexity in simple optical systems. Presented at Nonlinear Photonics (NP), Karlsruhe, Germany

We present the first detailed account of modelling kaleidoscope laser modes where the equivalent Fresnel number Neq and magnification M may assume arbitrary values. The convergence toward circularity is also investigated through extensive numerical c... Read More about Kaleidoscope lasers - Complexity in simple optical systems.

Helmholtz pulse propagation & spatially-dispersive light (2010)
Presentation / Conference
Christian, J., Hodgkinson, T., McDonald, G., & Chamorro-Posada, P. (2010, June). Helmholtz pulse propagation & spatially-dispersive light. Presented at Nonlinear Photonics (NP), Karlsruhe, Germany

We present the first detailed account of modelling pulses in Helmholtz-type nonlinear systems with both temporal and spatial dispersion. Exact analytical solitons will be reported, and their stability examined through mathematical analysis and comput... Read More about Helmholtz pulse propagation & spatially-dispersive light.

Turing instability: a universal route to spontaneous spatial fractals (2008)
Presentation / Conference
Huang, J., Christian, J., McDonald, G., & Chamorro-Posada, P. (2008, September). Turing instability: a universal route to spontaneous spatial fractals. Presented at European Optical Society Annual Meeting, Paris, France

We present the first predictions of spontaneous spatial fractal patterns in nonlinear ring cavities. New analyses reveal multi-Turing spectra characteristic of susceptibility
for spontaneous fractals. Extensive computer simulations confirm theoretic... Read More about Turing instability: a universal route to spontaneous spatial fractals.

Wide class of new fractal light sources [Invited plenary paper] (2008)
Presentation / Conference
McDonald, G., Christian, J., & Huang, J. (2008, September). Wide class of new fractal light sources [Invited plenary paper]. Presented at Advanced Optoelectronics and Lasers (CAOL), 2010 International Conference, Alushta, Crimea, Ukraine

Pattern emergence in Naturepsilas complex systems is mostly attributed to a classic Turing instability. There, a single length-scale becomes dominant and this defines a simple emergent structure (for example, a striped or hexagonal pattern). We have... Read More about Wide class of new fractal light sources [Invited plenary paper].

Turing instability: a universal route to spontaneous fractal patterns (2008)
Presentation / Conference
Huang, J., Christian, J., McDonald, G., & Chamorro-Posada, P. (2008, August). Turing instability: a universal route to spontaneous fractal patterns. Poster presented at National Photonics Conference, Photon 08, Heriot-Watt University, Edinburgh, UK

Turing instability is the tendency of the uniform states of a system to become spontaneously patterned in the presence of any small fluctuation [1]. Archetypal Turing- instability patterns include hexagons, squares, stripes, and rings. These simple s... Read More about Turing instability: a universal route to spontaneous fractal patterns.

Spontaneous self-synchronization mechanism for attosecond pulses (2008)
Presentation / Conference
Mcdonald, G., & Christian, J. (2008, August). Spontaneous self-synchronization mechanism for attosecond pulses. Poster presented at National Photonics Conference, Photon 08, Heriot-Watt University, Edinburgh, UK

Ultra-broadband multi-frequency Raman generation is a long-established technique for producing temporal bandwidths that can be of the order of the pump frequency. However, higher-than-optimal intensity beams reduce the bandwidth generated. Many works... Read More about Spontaneous self-synchronization mechanism for attosecond pulses.

Helmholtz solitons: fresh perspectives and new angles in photonics (2008)
Presentation / Conference
Christian, J., Mcdonald, G., & Chamorro-Posada, P. (2008, August). Helmholtz solitons: fresh perspectives and new angles in photonics. Poster presented at National Photonics Conference, Photon 08, Heriot-Watt University, Edinburgh, UK

Spatial solitons are self-localizing optical beams that can evolve with a stationary intensity profile when diffraction is off-set by material nonlinearity. Classic descriptions of spatial solitons [1] involve the paraxial approximation, which can im... Read More about Helmholtz solitons: fresh perspectives and new angles in photonics.

Soliton solutions of the nonlinear Helmholtz equation: propagation properties, interface effects and new families of exact solutions (2008)
Presentation / Conference
Chamorro-Posada, P., Sanchez-Curto, J., McDonald, G., & Christian, J. (2008, June). Soliton solutions of the nonlinear Helmholtz equation: propagation properties, interface effects and new families of exact solutions. Presented at Annual International Conference "Days on Diffraction" 2008, St. Petersburg, Russia

The properties of spatial optical solitons are most often studied using nonlinear Schroedinger (NLS) equations. These model the slow modulation the envelope of a linear wave solution experiences when propagation takes place in a wealky nonlinear medi... Read More about Soliton solutions of the nonlinear Helmholtz equation: propagation properties, interface effects and new families of exact solutions.

Helmholtz solitons: Maxwell’s equations, interfaces, bistability & counterpropagation (2008)
Presentation / Conference
Chamorro-Posada, P., Sanchez-Curto, J., Grikurov, V., McDonald, G., & Christian, J. (2008, June). Helmholtz solitons: Maxwell’s equations, interfaces, bistability & counterpropagation. Presented at Days on Diffraction, 2008. DD '08 International Conference, St. Petersburg, Russia

We give a brief overview of some new results in Helmholtz soliton theory. Firstly, fundamental considerations are made in terms of new contexts for Helmholtz solitons that arise directly from Maxwells equations. We then detail applications of Helmhol... Read More about Helmholtz solitons: Maxwell’s equations, interfaces, bistability & counterpropagation.

Broadband nonlinear optics: fractals, white light and multiplexing (2005)
Presentation / Conference
McDonald, G., Christian, J., Huang, J., Laughton, G., Chamorro-Posada, P., & Sanchez-Curto, J. (2005, February). Broadband nonlinear optics: fractals, white light and multiplexing. Presented at New Trends in Nonlinear Optics, Univesity of Strathclyde, Glasgow, UK

We will present an overview of some recent works that collectively fall under the banner of “broadband nonLinear optics”. Firstly, a generic mechanism for the spontaneous formation of spatial optical fractals has been proposed. Willie’s classic singl... Read More about Broadband nonlinear optics: fractals, white light and multiplexing.