1,721,033 research outputs found
Role of charge saturation in photorefractive dynamics of micron-sized beams and departure from soliton behavior
No full textExperimental and theoretical results indicate that miniaturized micron-sized nonlinear beam phenomenology in photorefractives leads to a regime qualitatively distinct from solitonlike propagation on consequence of the specific role of space-charge saturation. In the highly modulated conditions typical of beams, this contribution amounts to an effective electron self-action. © 2006 The American Physical Society
Counterpropagating reflection grating dark solitons in Kerr media
No full textWe investigate counterpropagating dark (black) solitons with different envelope profiles in defocusing Kerr media in the presence of a shallow reflection grating. In the quasi-Bragg-matching regime, we are able to predict the existence of a family of counterpropagating reflection dark solitons making use of their underlying connection with the counterpropagating nonlinear plane-wave pairs with intensities that coincide with the asymptotic soliton ones. In agreement, we find through modulation instability analysis that the nonlinear plane waves are stable in that very parameter region where these dark solitons exist. © 2007 The American Physical Society
Atomic Force Microscopy study of self-organized Ge islands grown on Si(100) by Low Pressure Chemical Vapour Deposition
No full text
Molding and Stretched Evolution of Optical Solitons in Cumulative Nonlinearities
No full textThe observation of initial time dynamics of self-trapping in photorefractive media indicates that optical spatial solitons supported by intense cumulative nonlinearities manifest temporally nonlocal signatures in the form of stretched exponential behavior. This general result, supported also by numerical predictions, is triggered by wave shaping in a time-constant buildup map, a consequence of the spatially resolved inertial response intrinsic to the geometrical transition from a diffracting to a self-focused beam, inherent to soliton appearance
Counterpropagating spatial solitons in reflection gratings with a longitudinally modulated Kerr nonlinearity
No full textWe investigate quasi-Bragg-matched counterpropagating spatial solitons in a reflection grating in the presence of a longitudinally modulated Kerr nonlinearity. The physical interplay of linear reflection and Kerr self-focusing with the modulation in the nonlinearity yields a variety of elaborate self-action mechanisms. We first analytically predict the existence of symmetric soliton pairs supported by a pure Kerr-like effective nonlinearity. We then analytically derive two families of solitons, associated with the linear grating eigenmodes, supported by an effective "incoherent" Kerr-like coupling arising from the exact balance between the modulation in the nonlinearity and the Kerr interaction due to beam interference
Observation of soliton ridge states for the self-imprinting of fiber-slab couplers
No full textWe investigate experimentally the energy exchange patterns and consequent propagation dynamics of an extended hybrid-dimensional interaction between a one-dimensional and a two-dimensional spatial soliton in a biased photorefractive crystal. Results show that conditions can be found in which the coupling manifests propagation invariant features. The mechanism hinges on mutual distortion through spatially nonlocal components of response, as opposed to standard wave overlap, which would lead to a diffusion of the needle into the slab mode. These nonlocal-nonlinearity-driven ridge modes represent the instrument for writing fiber-slab couplers, the key to attaining soliton-based wavelength selectivity with electroactivated features
Electro-optic switching through photorefractive needles
No full textWe demonstrate electro-optic spatial two-dimensional mode switching in a bulk sample of potassium-lithium-tantalate-niobate, mediated by two photorefractive needle solitons of opposite electroholographic charge, mutually embedded in their anisotropic structure. ©2002 Optical Society of America
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