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Propagation properties of nonparaxial spatial solitons (2000)
Journal Article
Chamorro-Posada, P., Mcdonald, G., & New, G. (2000). Propagation properties of nonparaxial spatial solitons. Journal of Modern Optics, 47(11), 1877-1886. https://doi.org/10.1080/09500340008232440

We present an analysis and simulation of the non-paraxial nonlinear Schroedinger equation. Exact general relations describing energy flow conservation and transformation invariance are reported, and then explained on physical grounds. New instabiliti... Read More about Propagation properties of nonparaxial spatial solitons.

Fractal modes in unstable resonators (1999)
Journal Article
Karman, G., Mcdonald, G., New, G., & Woerdman, J. (1999). Fractal modes in unstable resonators. Nature, 402, 138. https://doi.org/10.1038/45960

One of the simplest optical systems, consisting of two mirrors facing each other to form a resonator, turns out to have a surprising property. Here we show that the peculiar eigenmodes of unstable resonators are fractals, a finding that may lead to... Read More about Fractal modes in unstable resonators.

Excess noise in low Fresnel number unstable resonators (1999)
Journal Article
Mcdonald, G., New, G., & Woerdman, J. (1999). Excess noise in low Fresnel number unstable resonators. Optics Communications, 164(4-6), 285-295. https://doi.org/10.1016/S0030-4018%2899%2900194-7

Numerical calculations of excess noise factors in low Fresnel number unstable resonators are described in detail. Computed mode profiles in one transverse dimension together with associated Petermann K-factors are presented; dynamical considerations... Read More about Excess noise in low Fresnel number unstable resonators.

Fast algorithm for studying the evolution of optical solitons under perturbations (1999)
Journal Article
Chamorro-Posada, P., Mcdonald, G., New, G., & Fraile-Pelaez, F. (1999). Fast algorithm for studying the evolution of optical solitons under perturbations. IEEE Transactions on Magnetics, 35(3), 1558-1561. https://doi.org/10.1109/20.767268

A numerical algorithm is proposed for computing the eigenvalues of the linear scattering problem associated with the nonlinear Schrodinger equation. The numerical method allows a fast calculation of the dynamical evolution of the properties of optica... Read More about Fast algorithm for studying the evolution of optical solitons under perturbations.

Excess-noise dependence on intracavity aperture shape (1999)
Journal Article
Karman, G., Mcdonald, G., Woerdman, J., & New, G. (1999). Excess-noise dependence on intracavity aperture shape. Applied Optics, 38(33), 6874-6878. https://doi.org/10.1364/AO.38.006874

In lasers with nonorthogonal eigenmodes the excess-noise factor K can be large, especially in unstable-cavity lasers with hard-edged intracavity apertures. To the best of our knowledge, we report the first detailed study of the dependence of K on ape... Read More about Excess-noise dependence on intracavity aperture shape.

Nonlinear competing processes in multifrequency Raman generation (1998)
Journal Article
Mcdonald, G., Chan, Y., New, G., Losev, L., & Lutsenko, A. (1998). Nonlinear competing processes in multifrequency Raman generation. Journal of Modern Optics, 45(6), 1099-1110. https://doi.org/10.1080/09500349808230901

We investigate the extent to which the Raman generation of ultrabroad-band light will be affected by nonlinear competing processes. The model equations are generalized to incorporate an off-axis competing signal and a quantitative study is undertaken... Read More about Nonlinear competing processes in multifrequency Raman generation.

Non-paraxial solitons (1998)
Journal Article
Chamorro-Posada, P., Mcdonald, G., & New, G. (1998). Non-paraxial solitons. Journal of Modern Optics, 45(6), 1111-1121. https://doi.org/10.1080/09500349808230902

In this paper, we propose the use of ultranarrow soliton beams in miniaturized nonlinear optical devices. We derive a nonparaxial nonlinear Schrödinger equation and show that it has an exact non-paraxial soliton solution from which the paraxial solit... Read More about Non-paraxial solitons.

On the generation of ultra-broad bandwidth light in air at atmospheric pressure (1997)
Journal Article
atmospheric pressure. Journal of Physics B: Atomic, Molecular and Optical Physics, 30(21), L719-L725. https://doi.org/10.1088/0953-4075/30/21/002

We predict that ultra-broadband light consisting of over 150 distinct frequencies of comparable energy can be generated in air at atmospheric pressure by stimulated Raman scattering using resonant symmetric pumping. Nanosecond input pulses and the hi... Read More about On the generation of ultra-broad bandwidth light in air at atmospheric pressure.

Nondiffracting beams: travelling, standing, rotating and spiral waves (1996)
Journal Article
Chávez-Cerda, S., Mcdonald, G., & New, G. (1996). Nondiffracting beams: travelling, standing, rotating and spiral waves. Optics Communications, 123(1-3), 225-233. https://doi.org/10.1016/0030-4018%2895%2900538-2

A reformulation of nondiffracting beams, based on more general (travelling wave) solutions of the nonparaxial wave equation, is presented. Zero order nondiffracting beams are found to be radial standing waves arising from counterpropagating zero orde... Read More about Nondiffracting beams: travelling, standing, rotating and spiral waves.

Ultrabroad-bandwidth multifrequency Raman soliton pulse trains (1995)
Journal Article
McDonald, G. (1995). Ultrabroad-bandwidth multifrequency Raman soliton pulse trains. Optics Letters, 20(8), 822-824. https://doi.org/10.1364/OL.20.000822

I have discovered that in the coherent regime of ultrabroad-bandwidth Raman generation, a large number of long-lived soliton pulse trains are spontaneously generated. This novel solution of the dispersionless and highly transient regime, involving mo... Read More about Ultrabroad-bandwidth multifrequency Raman soliton pulse trains.

Ultrabroad-bandwidth multifrequency Raman generation (1994)
Journal Article
Mcdonald, G., New, G., Losev, L., Lutsenko, A., & Shaw, M. (1994). Ultrabroad-bandwidth multifrequency Raman generation. Optics Letters, 19(18), 1400-1402. https://doi.org/10.1364/OL.19.001400

We report on the modeling of transient stimulated rotational Raman scattering in H2 gas. We predict a multifrequency output, spanning a bandwidth greater than the pump frequency, that may be generated without any significant delay with respect to the... Read More about Ultrabroad-bandwidth multifrequency Raman generation.

Pattern formation in a passive Kerr cavity (1994)
Journal Article
Scroggie, A., Firth, W., Mcdonald, G., Tlidi, M., Lefever, R., & Lugiato, L. (1994). Pattern formation in a passive Kerr cavity. Chaos, Solitons and Fractals, 4(8-9), 1323-1354. https://doi.org/10.1016/0960-0779%2894%2990084-1

Analytical and numerical investigations of a cavity containing a Kerr medium are reported. The mean field equation with plane-wave excitation and diffraction is assumed. Stable hexagons are dominant close to threshold for a self-focusing medium. B... Read More about Pattern formation in a passive Kerr cavity.

Switching dynamics of spatial solitary wave pixels (1993)
Journal Article
Mcdonald, G., & Firth, W. (1993). Switching dynamics of spatial solitary wave pixels. Journal of the Optical Society of America B, 10(6), 1081-1089. https://doi.org/10.1364/JOSAB.10.001081

Separatrices and scaling laws in the switching dynamics of spatial solitary wave pixels are investigated. We show that the dynamics in the full model are similar to those in the plane-wave limit. Switching features may be indicated and explained by t... Read More about Switching dynamics of spatial solitary wave pixels.

Self-sustained modelocking using induced nonlinear birefringence in optical fibres (1993)
Journal Article
Langridge, P., Mcdonald, G., Firth, W., & Wabnitz, S. (1993). Self-sustained modelocking using induced nonlinear birefringence in optical fibres. Optics Communications, 97(3-4), 178-182. https://doi.org/10.1016/0030-4018%2893%2990136-S

A numerical study of self-sustained mode locking due to optically induced nonlinear birefringence is presented. The model incorporates a polarizer, a gain medium, a half-wave plate and a single-mode passive fibre in a ring cavity configuration. The... Read More about Self-sustained modelocking using induced nonlinear birefringence in optical fibres.

Dark spatial soliton break-up in the transverse plane (1993)
Journal Article
Mcdonald, G., Syed, K., & Firth, W. (1993). Dark spatial soliton break-up in the transverse plane. Optics Communications, 95(4-6), 281-288. https://doi.org/10.1016/0030-4018%2893%2990679-Y

We report on numerical simulations investigating the instabilities which arise when dark soliton solutions of the two-dimensional (2D) nonlinear Schrödinger equation are allowed to propagate in a 3D self-defocussing medium. Firstly, propagation of fu... Read More about Dark spatial soliton break-up in the transverse plane.

Spatial grid symmetries and reduced models in the simulation of beam counterpropagation in a nonlinear medium (1993)
Journal Article
Mcdonald, G., & Firth, W. (1993). Spatial grid symmetries and reduced models in the simulation of beam counterpropagation in a nonlinear medium. Journal of Modern Optics, 40(1), 23-32. https://doi.org/10.1080/09500349314550041

In the context of the nonlinear interaction of counterpropagating light beams, we demonstrate the unrealistic symmetries that arise in the simulation of spontaneous pattern formation when using square computational grids. We have formulated a general... Read More about Spatial grid symmetries and reduced models in the simulation of beam counterpropagation in a nonlinear medium.

Optical vortices in beam propagation through a self-defocussing medium (1992)
Journal Article
Mcdonald, G., Syed, K., & Firth, W. (1992). Optical vortices in beam propagation through a self-defocussing medium. Optics Communications, 94(5), 469-476. https://doi.org/10.1016/0030-4018%2892%2990589-J

We present numerical simulations and analysis of optical vortex propagation in a 3D self-defocussing medium. On plane wave background initial conditions composed of points and lines of phase discontinuity are shown, in some cases, to evolve towards a... Read More about Optical vortices in beam propagation through a self-defocussing medium.

Hexagon patterns in optical bistability (1992)
Journal Article
Firth, W., Scroggie, A., McDonald, G., & Lugiato, L. (1992). Hexagon patterns in optical bistability. Physical Review A, 46(7), R3609-R3612. https://doi.org/10.1103/PhysRevA.46.R3609

The mean-field model of optical bistability in a ring cavity is extended to include diffraction in two transverse dimensions. Nonlinear analysis in the neighborhood of the instability of the homogeneous solution indicates the formation of stable hexa... Read More about Hexagon patterns in optical bistability.

Spatial solitary-wave optical memory (1990)
Journal Article
Mcdonald, G., & Firth, W. (1990). Spatial solitary-wave optical memory. Journal of the Optical Society of America B, 7(7), 1328-1335. https://doi.org/10.1364/JOSAB.7.001328

We consider some features of spatial solitary-wave switching in a unidirectional ring cavity that is partially filled with a fast and saturably self-focusing nonlinear medium. Large (part-beam switched) solitary arrays are considered. It is found tha... Read More about Spatial solitary-wave optical memory.

All-optical switching in a nonlinear resonator (1990)
Journal Article
Mcdonald, G., & Firth, W. (1990). All-optical switching in a nonlinear resonator. Journal of Modern Optics, 37(4), 613-626. https://doi.org/10.1080/09500349014550701

In this paper we consider some features of all-optical switching in a unidirectional ring cavity which is partially filled with a fast and saturably nonlinear medium. A comparative study of cross-talk for both signs of nonlinearity, in a two pixel (w... Read More about All-optical switching in a nonlinear resonator.