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Publicações

Publicações por Maria Inês Carvalho

2012

Evolution of cubic-quintic complex Ginzburg-Landau erupting solitons under the effect of third-order dispersion and intrapulse Raman scattering

Autores
Carvalho, MI; Facao, M;

Publicação
PHYSICS LETTERS A

Abstract
The effects of third-order dispersion (TOD) and intrapulse Raman scattering (IRS) on the erupting solitons of the complex cubic-quintic Ginzburg-Landau equation are investigated by direct numerical simulations and linear stability analysis. Our results indicate that positive TOD eliminates eruptions on the leading edge of the soliton, whereas negative TOD cancels them on the other side. Moreover, the combined action of TOD and IRS is in certain cases able to eliminate explosions on both sides of the soliton, at much lower IRS values than with IRS alone. The profiles of the stationary solutions are increasingly asymmetric with TOD, and their velocity varies almost linearly with IRS. (C) 2012 Published by Elsevier B.V.

1995

Incoherently coupled soliton pairs in biased photorefractive crystals

Autores
Christodoulides, DN; Singh, SR; Carvalho, MI; Segev, M;

Publicação
Applied Physics Letters

Abstract
We show that incoherently coupled soliton pairs are possible in biased photorefractive crystals, under steady-state conditions. These solitons can propagate in bright-bright, dark-dark, as well as in bright-dark configurations. Such soliton pairs can be established provided that the carrier beams share the same polarization, wavelength, and are mutually incoherent. Relevant examples are provided where the photorefractive crystal is of the strontium barium niobate type. The characteristics and stability properties of these soliton states are also discussed in detail. © 1996 American Institute of Physics.

1996

Higher-order space charge field effects on the evolution of spatial solitons in biased photorefractive crystals

Autores
Singh, SR; Carvalho, MI; Christodoulides, DN;

Publicação
Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series

Abstract
The so-called screening solitons that occur in steady state when an external bias voltage is appropriately applied to a PR crystal are known to occur when the drift term dominates in the expression of the space charge field. In a recent study, the effects arising from first-order diffusion terms have also been investigated. It was found that the PR soliton can experience adiabatically self-deflection that varies linearly with the applied electric field. However, recent experiments suggest that this self-deflection can exceed that predicted by theory, especially in the regime of quite high bias fields. To account for this discrepancy, this paper investigates the effects of other higher-order electric field terms on the evolution of bright steady-state solitons in PR media.

1996

Incoherently coupled soliton pairs in biased photorefractive crystals

Autores
Singh, SR; Christodoulides, DN; Carvalho, MI; Segev, M;

Publicação
Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series

Abstract
It is shown that a new type of incoherently coupled soliton pairs is possible under steady-state conditions provided that their carrier beams share the same polarization and wavelength and are mutually incoherent. They can be readily realized in a simple experimental setup where the optical beams co-propagate collinearly in a biased photorefractive crystal, in which case they experience equal electro-optic coefficients. The two optical beams can be also slightly misaligned at the input so as to differentiate them at the output plane.

2012

Continuous Wave Supercontinuum Generation Aided by a Weaker Pulse Laser

Autores
Fernandes, G; Facao, M; Carvalho, MI; Rodrigues, S; Heidarialamdarloo, J; Pinto, AN; Ferreira, MF;

Publicação
NONLINEAR OPTICS AND APPLICATIONS VI

Abstract
The supercontinum generation has been achieved mainly by two different approaches, namely, with femtosecond intense pulses or using a continuous wave laser or larger pulses centered on the anomalous dispersion region. In order to improve temporal coherence, it has been suggested the introduction of a pulse seed or the propagation of both a large pulse pump and a small weaker continuous wave to control the soliton fission. Here we propose supercontinuum generation using a hybrid input, we pump with a continuous laser and copropagate a picosecond signal. We compare the bandwidth of the supercontinuum using only the continuous pump or the hybrid setup. Simulations of the generalized Schrodinger equation, using an adequate input-noise model to reproduce the spectrum of the continuous signal, are performed in order to investigate the supercontinuum generation in the optical communication window under different dispersion regimes.

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