The existence and stability of defect superlattice solitons in parity-time (PT) symmetric superlattice and simplelattice complex potentials are reported.Compared with defect simple-lattice solitons in similar potentials,the defect soliton in superlattice has a wider stable range than that in simple-lattice.The solitons' power increases with increasing propagation constant.For the positive defect,the solitons are stable in the whole region where solitons exist in the semi-infinite gap.For the zero defect,the solitons are unstable at the edge of the band.For the negative defect,the solitons propagate with the shape of Y at low propagation constant and propagate stably at the large one.
From the study of the dynamics for the ring-like soliton clusters,we find that there exists a critical value of the ring radius,d cr ,for the stationary rotation of the clusters with respect to the beam centre even in the presence of the relatively strong noise,and that the soliton clusters will not rotate but only undergo periodic collisions in the form of simple harmonic oscillator if the ring radius is large enough. We also show that the direction of the rotation can be opposite to the direction of phase gradient when the relative phase difference is within the domain 0 < |θ| < π,while along the direction of phase gradient when the relative phase difference is within the domain π < |θ| < 2π.
We study the propagation of (1+1)-dimensional spatial soliton in a nonlocal Kerr-type medium with weak nonlocality. First, we show that an equation for describing the soliton propagation in weak nonlocality is a nonlinear Schro¨dinger equation with perturbation terms. Then, an approximate analytical solution of the equation is found by the perturbation method. We also find some interesting properties of the intensity profiles of the soliton.
In this paper,we present a study on the propagation of the symmetrical optical vortices formed by two collinear Laguerre-Gauss solitons in strongly nonlocal nonlinear media.The optical vortices,which move along the beam axis as the light propagates,result in a rotation of the beam's transverse profile.This physical reason of the rotation is the Gouy phase acquired by the component beams.
