Multipole spatial vector solitons

Fundamental and multipole solitons in amplitude-modulated Fibonacci lattices

We investigated the existence and stability of fundamental and multipole solitons supported by amplitude-modulated Fibonacci lattices with self-focusing nonlinearity. Owing to the quasi-periodicity of Fibonacci lattices, families of solitons localized in different waveguides have different properties. We found that the existence domain of fundamental solitons localized in the central lattice is larger than that of solitons localized in the adjacent central waveguide. The former counterparts are completely stable in their existence region, while the latter have a narrow unstable region near the lower cut-off. Two families of dipole solitons were also comprehensively studied. We found the outer lattice distribution can significantly change the existence region of solitons. In addition, we specifically analyzed the properties of four complicated multipole solitons with pole numbers 3, 5, 7, and 9. In the Fibonacci lattice, their field moduli of multipole solitons are all asymmetrically distributed. The linear-stability analysis and direct simulations reveal that as the number of poles of the multipole soliton increases, its stable domain is compressed. Our results provide helpful insight for understanding the dynamics of nonlinear localized multipole modes in Fibonacci lattices with an optical nonlinearity.

Observation of multi-component spatial vector solitons of four-wave mixing

We report the observation of multi-component dipole and vortex vector solitons composed of eight coexisting four-wave mixing (FWM) signals in two-level atomic system. The formation and stability of the multi-component dipole and vortex vector solitons are observed via changing the experiment parameters, including the frequency detuning, powers, and spatial configuration of the involved beams and the temperature of the medium. The transformation between modulated vortex solitons and rotating dipole solitons is observed at different frequency detunings. The interaction forces between different components of vector solitons are also investigated.

Multipole vector solitons in nonlocal nonlinear media

We show that multipole solitons can be made stable via vectorial coupling in bulk nonlocal nonlinear media. Such vector solitons are composed of mutually incoherent nodeless and multipole components jointly inducing a nonlinear refractive index profile. We found that stabilization of the otherwise highly unstable multipoles occurs below certain maximum energy flow. Such a threshold is determined by the nonlocality degree.

Two-dimensional solitons with hidden and explicit vorticity in bimodal cubic-quintic media

We demonstrate that two-dimensional two-component bright solitons of an annular shape, carrying vorticities (m,+/-m) in the components, may be stable in media with the cubic-quintic nonlinearity, including the hidden-vorticity (HV) solitons of the type (m,-m) , whose net vorticity is zero. Stability regions for the vortices of both (m,+/-m) types are identified for m=1 , 2, and 3, by dint of the calculation of stability eigenvalues, and in direct simulations. In addition to the well-known symmetry-breaking (external) instability, which splits the ring soliton into a set of fragments flying away in tangential directions, we report two new scenarios of the development of weak instabilities specific to the HV solitons. One features charge flipping, with the two components exchanging angular momentum and periodically reversing the sign of their spins. The composite soliton does not directly split in this case; therefore, we identify such instability as an intrinsic one. Eventually, the soliton splits, as weak radiation loss drives it across the border of the ordinary strong (external) instability. Another scenario proceeds through separation of the vortex cores in the two components, each individual core moving toward the outer edge of the annular soliton. After expulsion of the cores, there remains a zero-vorticity breather with persistent internal vibrations.

Soliton molecules in trapped vector nonlinear Schrödinger systems

We propose a method to build a great variety of stable multisoliton "molecules" with coupled light beams in Kerr graded index (GRIN) media or atomic mixtures of Bose-Einstein condensates. We present a general theory and discuss several specific cases, including two-, three-, and four-atom molecules made up of Gaussian modes or vortices. A three-dimensional example is also presented.

Multicomponent dipole-mode spatial solitons

We study (2+1) -dimensional multicomponent spatial vector solitons with a nontrivial topological structure of their constituents and demonstrate that these solitary waves exhibit a symmetry-breaking instability, provided their total topological charge is nonzero. We describe a novel type of stable multicomponent dipole-mode solitons with intriguing swinging dynamics.

Rotating optical soliton clusters

We introduce the concept of soliton clusters--multisoliton bound states in a homogeneous bulk optical medium--and reveal a key physical mechanism for their stabilization associated with a staircaselike phase distribution that induces a net angular momentum and leads to cluster rotation. The ringlike soliton clusters provide a nontrivial generalization of the concepts of two-soliton spiraling, optical vortex solitons, and necklace-type optical beams.

Collisions between (2+1)D rotating propeller solitons

We study theoretically the collisions between (2+1)D rotating-dipole-type bimodal solitons and find that such interactions exhibit many interesting exchanges of angular momentum.

Dipole-mode vector solitons in anisotropic nonlocal self-focusing media

We demonstrate, theoretically and experimentally, that dipole-mode vector solitons created in biased photorefractive media possess a number of anisotropy-driven properties, such as stability of a selected orientation, wobbling, and incomplete rotation, owing to the anisotropic nonlocal response of the photorefractive non-linearity. Such features are found for higher-order (multipole) vector solitons, and they are carefully verified in an experiment.

Necklace-ring vector solitons

We introduce novel classes of optical vector solitons that consist of incoherently coupled self-trapped "necklace" beams carrying zero, integer, and even fractional angular momentum. Because of the stabilizing mutual attraction between the components, such stationary localized structures exhibit quasistable propagation for much larger distances than the corresponding scalar vortex solitons and expanding scalar necklace beams.