Solitons In Photovoltaic Photorefractive Crystals Research Articles

Generation and manipulation of spiral beams in photovoltaic photorefractive crystal twinning with mirroring diffusion management

The dynamics characteristics of spiral beams composed of two coherent solitons in photovoltaic photorefractive crystal twinning with mirroring diffusion management are investigated. The numerical simulations show that the orbits of spiral beams depend on the co-effect of the diffusion and coherence effects, and that spiral beams are forcedly rotated around the propagation axis set inside the twinning plane. Moreover, when the incident position of two coherent solitons relative to the twinning plane is reversed, the rotation direction of spiral beams is reversed accordingly. Furthermore, when the initial separation between (peak intensity of) two coherent solitons is adjusted, the rotation speed of spiral beams is adjusted accordingly.

Surface defect lattice solitons in photovoltaic-photorefractive crystals

We report that surface defect lattice solitons (SDLSs) can be supported at the interface between the photonic lattices with a defect and the uniform photovoltaic-photorefractive (PP) crystal. We show that these SDLSs exist only in the semi-infinite gap when the defect is positive and both in the semi-infinite gap and the first gap when the defect is negative. For a positive defect, SDLSs are stable in the high and low power regions and unstable in the moderate power region. For a negative defect, SDLSs in the semi-infinite gap are stable in the moderate power region and unstable in the high and low power regions. In the first gap, SDLSs are stable in the all power regions. We find that the stable region of SDLSs increases with the positive defect strength and decreases with an increase in the negative defect strength and the power of SDLSs decrease with an increase in the positive defect strength and increase with the negative defect strength.

Two-Dimensional Optical Lattice Solitons in Photovoltaic-Photorefractive Crystals

We study two families of two-dimensional bright lattice solitons in photovoltaic-photorefractive crystals. It is shown that self-focusing and self-defocusing lattice solitons are possible only when their power level exceeds a critical threshold. It is found that self-focusing lattice solitons exist not only in the semi-infinite band gap, but also in the first band gap, whereas self-defocusing lattice solitons exist only in the first band gap. The structures of these lattice solitons are also analyzed. Our results indicate that a self-focusing lattice soliton in the semi-infinite band gap is more confined than in the first band gap so its tails in the first band gap occupy many lattice sites; when a self-defocusing lattice soliton is close to the second band, the self-defocusing lattice soliton is more confined so its tails occupy a few lattice sites.

Interactions of dark solitons in photovoltaic photorefractive crystals with diffusion nonlinearity

We investigate the interaction of spatial dark optical soliton pair in open-circuit photovoltaic photorefractive crystals by considering the effect of background light and diffusion nonlinearity. We show that the spatial dark solitons repel each other and travel along different trajectories for the coherent interactions that one undergoes reflection and the other one deflects significantly when they are closely overlapped, and the dark solitons attract and deflect simultaneously along a parabolic trajectory for the case of incoherent interactions. The deflection distance depends on the intensities and the initial separation between the dark solitons.

Self-deflection of partially spatially incoherent beams and solitons in photovoltaic photorefractive crystals

By considering the effect of background light and diffusion, the self-deflection process of partially spatially incoherent (PSIC) beams and photovoltaic (PV) solitons in open-circuit PV photorefractive crystals has been investigated by employing numerical method and the perturbation technique, respectively. The results from the two approaches are in good agreement: the center of PSIC PV solitons moves on a parabolic trajectory, which is similar to those of coherent solitons. In addition, we also discuss that the dependence of self-deflection effect on the coherent parameter θ 0 and find it is slight relative to θ 0 for quasi-soliton but decreases monotonously with θ 0 for PSIC beam.

Incoherently coupled screening photovoltaic spatial solitons in biased photovoltaic photorefractive crystals

Propagation characteristics and stability properties of two-component composite screening photovoltaic spatial solitons have been analyzed in this paper. Employing paraxial ray approximation, we have identified a very large family of new two-component composite screening photovoltaic solitons in photovoltaic–photorefractive crystals. These composite solitons can exist only when the carrier beams have the same polarization, wavelength and are mutually incoherent. We have identified a wide parameter space involving spatial width and power where these composite solitons can exist as a stationary entity. The identified regions of existence of solitons give a deeper understanding of these solitons and reveal some interesting properties. We have shown that composite solitons with different widths cannot propagate as a stationary entity. A relevant example has been provided where the crystal is LiNbO 3 or BaTiO 3. In addition, we have shown that in the new family of solitons, a degenerate pair with equal peak power possesses bistable property. Both paraxial theory and numerical simulation show that the identified family of composite solitons is stable.