Nina V. Vyssotina

Instability of guided-wave transverse structure in layered nonlinear systems

A method is presented for the three-dimensional stability analysis of nonlinear guided waves that are propagating in layered systems. The increments of the perturbation increase are calculated for a film with a nonlinear substrate.

Numerical simulations of interaction of bright spatial solitons in medium with saturable nonlinearity

Abstract We present numerical simulations of interaction of bright transversely two-dimensional solitons with different topological indices in a homogenous transparent medium with saturable self-focusing nonlinearity of refraction index. We describe also the propagation and interaction of powerful light beams, including vortices, in such medium.

Optical needles: ultra-narrow Maxwell's spatial solitons in Kerr media

The limiting levels of light energy concentration can be achieved by shortening of laser pulses (femto- and attosecond range) and by transverse squeezing of beams (sub-micrometer sizes). The latter approach can be realized in media with nonlinearity of refractive index of self-focusing type.

Fermi-Ulam problem for solitons in dynamical cavities

We analyze regular and chaotic dynamics of optical solitons and solitons of matter waves in a cavity with periodically oscillating mirrors. For wide-aperture nonlinear cavities different types of spatial vector solitons are found. Their collisions can change the soliton type.

Few cycle dissipative soliton pulses

We find a novel class of stable dissipative solitary waves with discrete velocities and few cycle temporal duration in a composite medium containing active and passive atoms.

Polarization structure of nonparaxial spatial solitons- "optical needles" in media with different mechanisms of self-focusing nonlinearity

This report investigates, both semianalytically and numerically, nonparaxial transversely two-dimensional spatial solitons for an arbitrary mechanism of the medium Kerr nonlinearity when the phenomenon of rotation of the polarization ellipse takes place. Numerically, the nonlinear propagation of laser radiation in the form of a fairly long pulse and a narrow beam has been studied. The effective self-focusing and formation of optical needles occur in the centre of the pulse. The field longitudinal component is especially large in the case of orientation mechanism of self-focusing.

Polarization state of spatial optical solitons: effects of nonparaxiality and anisotropy

We present numerical results and semi-analytical theory for determination of characteristics of transversely 2D spatial optical solitons under conditions of small deviations from paraxiality. For the cases of the Kerr and quadratic nonlinearities, we show that the polarization is elliptic and changes over the soliton cross-section.

Modeling of the observed image of an object situated under the sea surface and distorted by surface waves

We propose a method of numerical simulation of an image formation in vision systems looking through the waved water surface. The simulation of radiation propagation through the waved sea surface and sea depth is realized in ray approximation. Waviness is simulated as evolving in the time random surface with given spectrum of elevations and dispersion relation. New values of angular, energy, and polarization parameters of each ray in the beam after its refraction and reflection at a given surface point are calculated by means of Fresnel formulae. Seawater medium is split in the layers with thickness chosen from the condition that water characteristics can be considered as constant and that multiple scattering of a ray can be neglected within a layer. Attenuation of beam energy corresponds to the length of the beam path in the layer, and probability of beam scattering at a random angle within a layer is determined by phase scattering function. We have obtained numerically instantaneous and averaged over different exposition times images of 2D self-luminous and located mira made up from spokes and situated at various depths for various values of wind velocities and seawater scattering coefficients. Influence of water and waviness parameters on the image quality has been analyzed.

Scientific software for numerical simulation of propagation of laser radiation through atmosphere

We propose the code for simulation of laser radiation propagation through turbulent and nonlinear atmosphere in the wave and ray approximations. The code has graphic shell and convenient interface.

Collisions of spatial solitons in a medium with saturable nonlinearity

We present results of theoretical investigations of collisions of spatial solitons. For the case of large collision angles the analytic theory has been worked out. Numerical investigations of power exchange among the solitons with small collision angles were carried out. The possibility of new soliton creation after collision has been discovered.