Kaiyun Zhan

Spatial solitons in centrosymmetric photorefractive crystals due to the two-photon photorefractive effect

We present the evolution equation of one-dimensional spatial solitons in centrosymmetric photorefractive media due to the two-photon photorefractive effect. It is shown theoretically that both dark and bright spatial solitons can exist in two-photon centrosymmetric photorefractive media under steady-state conditions. Moreover, we also investigate the self-deflection of steady-state bright solitons arising from the diffusion effects.

Dark and gray solitons in nematic liquid crystals

The dark and gray solitons in nematic liquid crystals with defocusing nonlinearities were theoretically analyzed by a variational approach. It was found that the nonlocal nonlinearity drastically affects the width of the dark and gray solitons and also affects the velocity of the gray solitons. Our results also show that an increase of the degree of nonlocality leads to a decrease of the soliton width in the weakly nonlocal limit, while nonlocality has the opposite effect in the nonlocal limit.

Beam splitters in inhomogeneous nonlocal media

We numerically investigate the dark soliton interaction in an inhomogeneous nonlocal medium and find that the variation of the longitudinal nonlocality disturbs the pair of dark solitons and splits them into two separate dark solitons with the same escape angle but opposite deflection directions. In particular, the escape angle monotonically increases with an increase of the inhomogeneous variation rate. We show that the waveguide induced by the dark soliton interaction yields a complete family of beam splitters for trapped linear beams. Interestingly, a weak probe signal is split into two beams in this waveguide, and the two beams have different powers, which could be controlled by adjusting the nonlocality variation rate.

Beam steering in a nonlocal medium with inhomogeneous nonlinearity

We address the dynamics of out-of-phase soliton pairs and dipole solitons in a nonlocal medium with inhomogeneous nonlinearity, and demonstrate their self-splitting into two individual solitons. We reveal that this self-splitting strongly depends on the variation of the longitudinal nonlinearity and it can be employed for efficient control of the soliton trajectories. We also demonstrate that the index waveguide, which is induced by the soliton pairs and the dipole soliton bound state, yields a family of special waveguides and beam splitters for trapped linear beams. Interestingly, the switching efficiency of this beam splitter could be controlled by adjustment of the longitudinal nonlinearity.