Stable propagation of cylindrical-vector vortex solitons in strongly nonlocal media

Abstract

We report the experimental observation of cylindrical-vector vortex solitons (CVVSs) in lead glass with strongly thermal nonlocal nonlinearity. The formations of radially and angularly polarized solitons with topological charge of l = 1 were observed. We show that the ring profiles and the polarization distributions of the two first-order CVVSs can be preserved. We numerically prove that the first-order CVVS is stable, and the higher-order CVVSs with l ≥ 2 are unstable based on the linear stability analysis method.

Stable propagation of the Poincaré polarization solitons in strongly nonlocal media

“…It must be pointed out that the propagation distances of the first-order PPSs are relatively short in the experiment. This does not because they are inherently unstable when propagate longer, but because of the unavoidable loss, such as light scattering and absorption [22,25,34,37]. Next, we examined the beam polarization states by inserting a LPA in front of the CCD camera.…”

“…The electric field E with an amplitude A can be expressed as where e 1 , e 2 are consistent with those in equation ( 1). The propagation of vector solitons in lead glass can be described by the coupled vector Helmholtz equation and the Poisson equation [22]. Taking account of the paraxial and slowly varying envelope approximations, we directly provide two coupled partial differential equations about the two components of the vector amplitude A in a dimensionless form:…”

“…Under the circumstance of the radially symmetric excitation (circular cross section of the media, normal and central incidence, cylindrical beam spots), n = − ´r0 0 G 0 (r, ρ)q 2 (ρ)dρ, where the Green's function G 0 (r, ρ) is given by [27] and r 0 is the normalized sample radius. We refer to the Newton-iterative method used in [22] to find the solution of equation (5). Due to the invariance of the soliton solutions under the scale transformations [38] To analyze the stability of the PPSs, we performed the linear stability analysis of its solution with the azimuthal perturbation…”

“…This helps lead glass to support the stable propagation of two orthogonally-polarized vortex solitons [37,38]. Recently, the stable propagation of the first-order cylindrical vector vortex soliton is experimentally and theoretically demonstrated in lead glass [22]. From a point of view of the complexity of polarization distribution, cylindrical vector vortex soliton is the most basic nonuniformly-polarized soliton.…”

“…In the nonlinear optical regime, most studies showed that vector beams cannot form stable solitons with spatially inhomogeneous polarization in Kerr media [15][16][17]. The collapse of the nonuniformly-polarized soliton can be arrested by using saturable nonlinearities [18], photorefractive crystals [19][20][21] or nonlocal materials [22,23]. The nonlocal properties of materials, either orientational [24] or thermal [25], can 'average' the angular modulation instability which makes the nonlocal spatial solitons more stable than local ones.…”