A. V. Mamaev

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– We present experimental observations of hexagonal patterns in strongly anisotropic non-linear optical media. Close to threshold rolls are observed. As the non-linearity is increased a transition from rolls to hexagons, leading finally to a pure hexagonal state, is observed. A mean-field model, in agreement with experiments, shows that the anisotropy locks(More)
We find and analyze bound dipole solitary solutions in media with anisotropic nonlocal photorefractive material response. The dipole solutions consist of two elliptically shaped Gaussian-type beams separated by several diameters, and with a p phase shift between their fields. Spatial evolution of two initially round Gaussian beams and their convergence to(More)
We analyze the evolution of s111d dimensional dark stripe beams in bulk media with a photorefractive nonlinear response. These beams, including solitary wave solutions, are shown to be unstable with respect to symmetry breaking and formation of structure along the initially homogeneous coordinate. Experimental results show the complete sequence of events(More)
We report on selection and stabilization of transverse optical patterns in a feedback mirror experiment. Amplitude filtering in the Fourier plane is used to select otherwise unstable spatial patterns. Optical turbulence observed for nonlinearities far above the pattern formation threshold is stabilized by low-pass filtering of the optical power spectrum.(More)
Vortical excitations with quantized circulation appear in superfluids, superconductors, and nonlinear optics in the presence of a repulsive or self-defocusing nonlinearity. The nonlinear Schrödinger equation with cubic nonlinearity has been used extensively to describe vortex solitons in two transverse dimensions, as was done first in the context of vortex(More)
– We present the theory and the experimental observation of break-up of twodimensional bright spatial solitons propagating in a three-dimensional bulk photorefractive nonlinear medium due to transverse modulation instability. Solitary wave (self-bound) solutions of nonlinear propagation equations are a fascinating topic of nonlinear dynamics. The analysis(More)
– We investigate self-focusing in bulk media with anisotropic nonlocal photorefractive response. Analytical results demonstrate the possibility of the existence of anisotropic soliton solutions. Self-focusing of Gaussian beams and their convergence to elliptically shaped soliton solutions is investigated theoretically and demonstrated experimentally. In(More)
We present a theoretical and experimental study of the propagation, decay, and interaction of optical vortices in media with an anisotropic nonlocal nonlinearity. The initial stage of decay of a circular vortex is characterized by charge dependent rotation, and stretching of the vortex. Our results suggest that a compact vortex of unit topological charge(More)
Propagation and spatial evolution of light beams in nonlinear media is a central topic of nonlinear optical dynamics. There has been continuing interest in this topic since the initial investigations of self-trapping of light beams in nonlinear media @1,2#. Analysis of the stability and nonlinear evolution of solitary-wave solutions of nonlinear propagation(More)
We study pattern formation that is due to modulational instability of noncollinear counterpropagating beams. Angular misalignment of the pumps over a broad range leads to the generation of lines oriented perpendicular to the plane of the pump beams. A theoretical expression for the angular separation of the lines is in close agreement with observations.(More)