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 LiNbO₃ or BaTiO₃. 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.