Spatial solitons in optically induced gratings

Abstract

We study experimentally nonlinear localization effects in optically induced gratings created by interfering plane waves in a photorefractive crystal. We demonstrate the generation of spatial bright solitons similar to those observed in arrays of coupled optical waveguides. We also create pairs of out-of-phase solitons, which resemble twisted localized states in nonlinear lattices.

Self-trapping of optical vortices in waveguide lattices with a self-defocusing nonlinearity

“…One of the key paradigms of discretizing light behavior in periodical structures is the self-trapped states better known as "lattice solitons" [3][4][5][6][7][8]. Such discrete spatial solitons typically have their propagation constants residing in the semi-infinite gap (arising from the total internal reflection) or inside a true photonic band gap (arising from the Bragg reflection).…”

“…In all experiments, the lattice beam is ordinarily-polarized while the vortex beam is extraordinarily-polarized. Thus the lattice beam will undergo nearly linear propagation in the crystal while the vortex beam will experience a large nonlinearity due to the anisotropic property of the photorefractive crystal [5][6][7][8]. An incoherent white light source was used as a background illumination to fine tune the screening nonlinearity.…”

Coupled-mode theory for spatial gap solitons in optically induced lattices

“…Provided that the intensity of the probe beam, |E| 2 , is much weaker than that of the grating, I 0 , one may neglect the feedback action of the probe beam on the grating (a perturbative calculation within the framework of an extended model, that includes equations for both the latticeforming and probe fields, shows that the feedback exactly cancels out at the first order in 1/I 0 ). Then the evolution of the local amplitude E(x, z) of the probe beam obeys the known equation [3,4], whose normalized form is i ∂E ∂z + 1 2…”

Oscillations of two-dimensional solitons in harmonic and Bessel optical lattices

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We consider parametric amplification of two-dimensional spatial soliton swinging in longitudinally modulated harmonic and Bessel lattices in Kerr-type saturable medium.We show that soliton center oscillations along different axes in two-dimensional lattices are coupled, which give rise to a number of interesting propagation scenarios including periodic damping and excitation of soliton oscillations along perpendicular axes, selective amplification of soliton swinging along one of transverse axes and enhancement of soliton spiraling.PACS numbers: 42.65.Jx; 42.65.Tg; 42.65.Wi Solitons in optically induced lattices were predicted and experimentally observed in photorefractive crystals in one and two transverse dimensions [1][2][3][4]. In photorefractive materials harmonic lattices are usually formed by the interference pattern of several plane waves whose intensity and intersection angles define the lattice depth and period.

Such kind of lattices may be used for engineering of systems with tunable discreteness since they can operate in both regimes of weak and strong coupling between neighboring sites depending on the depth and period of refractive index modulation.

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“…PACS numbers: 42.65.Jx; 42.65.Tg; 42.65.Wi Solitons in optically induced lattices were predicted and experimentally observed in photorefractive crystals in one and two transverse dimensions [1][2][3][4]. In photorefractive materials harmonic lattices are usually formed by the interference pattern of several plane waves whose intensity and intersection angles define the lattice depth and period.…”