Research Interests:
Research Interests:
E Pap&, G. D'Alesssndmz, W.J. Firth3 and G.-L. O p p 3 ' Dept. of Physics, University of Monchesrw Munckeserter MI3 9PL. E n g l a d , UK 21: ( + ) M I 6 1 2754067. Fm: (+I 44 161 275 4056 €-mil: plpo~@reynoldr.ph.monau.uk... more
E Pap&, G. D'Alesssndmz, W.J. Firth3 and G.-L. O p p 3 ' Dept. of Physics, University of Monchesrw Munckeserter MI3 9PL. E n g l a d , UK 21: ( + ) M I 6 1 2754067. Fm: (+I 44 161 275 4056 €-mil: plpo~@reynoldr.ph.monau.uk Dept. ofMolkmdc$, University of Soulhrunplon. Sourhnmprnn SO17 IBJ, E n ~ l d UK Tel: (+I44 1703 593650, Far: f+) 44 1703 595147E-mil: gd@miha.mton.nc.uk DIP: ofphyrics, Uniwrsify of Stmlhciyde. Clargov G4 ONC, ScoIM, UK Tel: ( + / 4 4 I 4 1 5483761, Far: (+)M 141 5522891. E--!/: gronlueoQphys.armih.ocult
Research Interests:
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
ABSTRACT
Research Interests:
We present a distinctive approach to the numerical modeling of pulsed nanosecond optical parametric oscillators (OPOs). Our model expands a recent procedure to the case of a nondegenerate, singly resonant OPO. A single partial... more
We present a distinctive approach to the numerical modeling of pulsed nanosecond optical parametric oscillators (OPOs). Our model expands a recent procedure to the case of a nondegenerate, singly resonant OPO. A single partial differential equation describes the temporal and transverse variations of the resonated signal field and also accounts for diffraction, phase mismatching, and idler absorption. The model's results
Research Interests:
An analogy between transverse coupling of bistable optical devices and nonlinear dynamics is exploited to demonstrate that chaos in the dynamics is necessary for independent operation of the elements of a bistable array.
Research Interests:
ABSTRACT
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
We investigate the effect of pump phase noise on the collective backscattering of light by a cold, collisionless atomic gas. We show that for a partially coherent pump field, the growth rate of the backscattered field is reduced relative... more
We investigate the effect of pump phase noise on the collective backscattering of light by a cold, collisionless atomic gas. We show that for a partially coherent pump field, the growth rate of the backscattered field is reduced relative to that for a coherent pump, but the backscattered intensity can be increased. Our results demonstrate that fluctuations and noise can play a counterintuitive role in nonlocally coupled many-body systems.
Research Interests:
In spatially extended Turing-unstable systems, parameter variation should, in theory, produce only fully developed patterns. In experiment, however, localized patterns or solitons sitting on a smooth background often appear. Addition of a... more
In spatially extended Turing-unstable systems, parameter variation should, in theory, produce only fully developed patterns. In experiment, however, localized patterns or solitons sitting on a smooth background often appear. Addition of a nonlocal nonlinearity can resolve this discrepancy by tilting the "snaking" bifurcation diagram characteristic of such problems.
Research Interests:
ROS: The Research Output Service. ROS Home ROS Home. Advanced Search Advanced Search. ROS Quick Finder. ...
ABSTRACT
Research Interests:
... and Applied Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 ONG, Scotland ... 4tR/3, and thus has a high threshold unless -t<<t R. For X sin 6 < 0 ... Conversely, the slow... more
... and Applied Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 ONG, Scotland ... 4tR/3, and thus has a high threshold unless -t<<t R. For X sin 6 < 0 ... Conversely, the slow media which often have large Kerr coefficients will tend to show pattern ...
Research Interests:
Research Interests:
Research Interests:
We present two-dimensional numerical simulations of a nonlinear optical system made of a thin slice of Kerr material and a feedback mirror. The phase modulation induced on the light by the nonlinear material is transformed into amplitude... more
We present two-dimensional numerical simulations of a nonlinear optical system made of a thin slice of Kerr material and a feedback mirror. The phase modulation induced on the light by the nonlinear material is transformed into amplitude modulation by propagation to the ...
Research Interests:
Research Interests:
Hexagonal structures have been observed and predicted in a number of nonlinear optical systems. After a brief general review of the field, the case of a slice of Kerr medium with single feedback mirror is analyzed in some detail. Its... more
Hexagonal structures have been observed and predicted in a number of nonlinear optical systems. After a brief general review of the field, the case of a slice of Kerr medium with single feedback mirror is analyzed in some detail. Its analogy to liquid-crystal light valve systems with feedback loop is noted. Recent experimental results are mentioned, and analytical results based on symmetry analysis are presented, along with simulations, for the practically important case of Gaussian beam excitation.
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
We apply a versatile numerical technique to establishing the existence of cavity solitons (CS) in a semiconductor microresonator with bulk GaAs or multiple quantum well GaAs/AlGaAs as its active layer. Based on a Newton method, our... more
We apply a versatile numerical technique to establishing the existence of cavity solitons (CS) in a semiconductor microresonator with bulk GaAs or multiple quantum well GaAs/AlGaAs as its active layer. Based on a Newton method, our approach implies the evaluation of the linearized operator describing deviations from the exact stationary state. The eigenvalues of this operator determine the dynamical stability of the CS. A typical eigenspectrum contains a zero eigenvalue with which a "neutral mode" of the CS is associated. Such neutral modes are characteristic of models with translational symmetry. All other eigenvalues typically have negative real parts large enough to cause any excitations to die out in a few medium response times. The neutral mode thus dominates the response to external random or deterministic perturbations, and its excitation induces a simple translation of the CS, which are thus stable and robust. We show how to relate the speed with which a CS moves under external perturbations to the projection of the perturbations on to the neutral mode, and give some examples, including weak gradients on the driving field and interaction with other CS. Finally, we show that the separatrix between two stable coexisting solutions: the homogeneous solution and the CS is the intervening unstable CS solution. Our results are important with a view to future applications of CS to optical information processing.
Research Interests:
Research Interests:
Research Interests:
The basic physics of nonlinear optics in semiconductors is reviewed. Optical bistability due to increasing absorption and in a Kerr cavity is discussed, as are spatial solitons in a Kerr medium. These introduce recent research on... more
The basic physics of nonlinear optics in semiconductors is reviewed. Optical bistability due to increasing absorption and in a Kerr cavity is discussed, as are spatial solitons in a Kerr medium. These introduce recent research on spontaneous pattern formation and soliton-like structures in semiconductor cavity models. Applications to optical information processing are discussed, and simulations of a soliton array memory presented.
Research Interests:
... W. J . FIRTH Physics Department, Strathclyde University, Glasgow, Scotland and I. GALBRAITH Institut for Theoretische Physik, Rober-Mayer Str., 8, Frankfurt, D-6000, FR Germany (Received 3.7uly 1986) Abstract. ... Page 2. 138 W. Y.... more
... W. J . FIRTH Physics Department, Strathclyde University, Glasgow, Scotland and I. GALBRAITH Institut for Theoretische Physik, Rober-Mayer Str., 8, Frankfurt, D-6000, FR Germany (Received 3.7uly 1986) Abstract. ... Page 2. 138 W. Y. Firth and I. Galbraith ...
Research Interests:
ABSTRACT
Research Interests:
The excess noise factor is calculated analytically for a very general class of optical cavities, and is shown to have a superexponential dependence on cavity misalignment, easily attaining values of order 10(10). The physical basis is... more
The excess noise factor is calculated analytically for a very general class of optical cavities, and is shown to have a superexponential dependence on cavity misalignment, easily attaining values of order 10(10). The physical basis is shown to be "ransient gain" associated with amplified spontaneous emission. Similarly dramatic effects of symmetry breaking can be expected in other physical systems with non-normal modes.
Research Interests:
Research Interests:
... The use of a Newton method is advantageous because, as a by-product of this process ... If there is a population inversion, the sign of the nonlinear index change is reversed ... While semiconductors have some quasi-two-level... more
... The use of a Newton method is advantageous because, as a by-product of this process ... If there is a population inversion, the sign of the nonlinear index change is reversed ... While semiconductors have some quasi-two-level properties, here one really must generalise our previous ...
Research Interests:
ABSTRACT
Research Interests:
Optical modulators and bistable devices using molecular gases " in "Proceedings of the Topical Meeting on Digital Optical Circuit Technology ", Schliersee , Germany , 1984 , Advisory Group for Aerospace Research & Development (AGARD) Conference Proceedings No. 362 , Ed. Billy L. Dove (AGARD , Neu...more