Search results for "Pattern Formation"
showing 10 items of 408 documents
Cavity solitons in bidirectional lasers.
2007
We show theoretically that a broad area bidirectional laser with slightly different cavity losses for the two counterpropagating fields sustains cavity solitons (CSs). These structures are complementary, i.e., there is a bright (dark) CS in the field with more (less) losses. Interestingly, the CSs can be written/erased by injecting suitable pulses in any of the two counterpropagating fields.
Strong lowering of the mirrorless optical oscillation threshold by angular mismatches for nonlocal photorefractive nonlinearity.
2008
We show that the introduction of an angular mismatch for the pump waves results, in the case of nonlocal photorefractive nonlinearity, in a strong almost twofold decrease of the threshold value of the coupling strength for the mirrorless optical oscillation. This surprising feature will lead to a strong modification of the threshold and near-threshold behavior of a vast variety of optical oscillators based on the photorefractive phase conjugation and involving finite-size light beams.
Quadratic solitons in 2D nonlinear photonic crystals
2007
We report on the first observation of spatial solitons in a 2D nonlinear photonic crystal. The experiments were performed in an hexagonally poled LiNbO3 waveguide designed for second harmonic generation from ~1.55 micron.
Motion of compactonlike kinks.
1999
We analyze the ability of a compactonlike kink (i.e., kink with compact support) to execute a stable ballistic propagation in a discrete Klein-Gordon system with anharmonic coupling. We demonstrate that the effects of lattice discreteness, and the presence of a linear coupling between lattice sites, are detrimental to a stable ballistic propagation of the compacton, because of the particular structure of the small-oscillation frequency spectrum of the compacton in which the lower-frequency internal modes enter in direct resonance with phonon modes. Our study reveals the parameter regions for obtaining a stable ballistic propagation of a compactonlike kink. Finally we investigate the interac…
Exact dark soliton solutions for a family ofNcoupled nonlinear Schrödinger equations in optical fiber media
2001
We consider a family of N coupled nonlinear Schr\"odinger equations which govern the simultaneous propagation of N fields in the normal dispersion regime of an optical fiber with various important physical effects. The linear eigenvalue problem associated with the integrable form of all the equations is constructed with the help of the Ablowitz-Kaup-Newell-Segur method. Using the Hirota bilinear method, exact dark soliton solutions are explicitly derived.
Photonic Nambu-Goldstone bosons
2017
We study numerically the spatial dynamics of light in periodic square lattices in the presence of a Kerr term, emphasizing the peculiarities stemming from the nonlinearity. We find that, under rather general circumstances, the phase pattern of the stable ground state depends on the character of the nonlinearity: the phase is spatially uniform if it is defocusing whereas in the focusing case, it presents a chess board pattern, with a difference of $\pi$ between neighboring sites. We show that the lowest lying perturbative excitations can be described as perturbations of the phase and that finite-sized structures can act as tunable metawaveguides for them. The tuning is made by varying the in…
Dissipation-induced coherent structures in Bose-Einstein condensates.
2008
We discuss how to engineer the phase and amplitude of a complex order parameter using localized dissipative perturbations. Our results are applied to generate and control various types of atomic nonlinear matter waves (solitons) by means of localized dissipative defects.
Soliton rains in a fiber laser: An experimental study
2010
Rains of solitons constitute a class of nonlinear dynamics of dissipative soliton ensembles that we briefly reported in Opt. Express 17, 11776 (2009) from a fiber laser experiment. The existence of a relatively intense noisy background together with several tens of soliton pulses aggregated in a condensed soliton phase constitutes a necessary condition for their appearance. New soliton pulses form spontaneously from the background fluctuations and drift until they reach the condensed soliton phase. We here relate in detail the experimental conditions under which soliton rains manifest and their key features, describe related dynamics observed in their vicinity, and propose an explanation fo…
Oscillation spectra of semilinear photorefractive coherent oscillator with two pump waves
2002
The transition of the single-frequency oscillation of a semilinear photorefractive coherent oscillator for sufficiently large coupling strengths into two-frequency oscillation is predicted and is observed experimentally. The critical value of coupling strength at which the bifurcation occurs is a function of pump-intensity ratio and cavity losses. For certain combinations of these parameters, the critical coupling strength for spectrum bifurcation becomes smaller than the threshold coupling strength: in these cases double-frequency oscillation appears at the threshold. The supercritical bifurcation in the oscillation spectrum is analogous to the second-order phase transition.
Instability of single-frequency operation in semilinear photorefractive coherent oscillators.
2002
The transition of the single-frequency oscillation of a semilinear photorefractive coherent oscillator for sufficiently large coupling strengths into two-frequency oscillation is predicted and is observed experimentally. The critical value of the coupling strength at which the bifurcation occurs is a function of pump intensity ratio and cavity losses. The supercritical bifurcation in the oscillation spectrum is analogous to the second-order phase transition.