We study spatially localized optical vortices created by self-trapping of partially incoherent light with a phase dislocation in a biased photorefractive crystal. In contrast to a decay of coherent self-trapped vortex beams due to the azimuthal modulational instability, the incoherent vortices are stabilized for large values of the spatial incoherence; this… (More)
We describe the direct experimental measurement of the transverse propagation velocities of dark spatial solitons. Good agreement is obtained from a comparison of the velocities measured experimentally and the velocities predicted by the two-dimensional theory of Zakharov and Shabat [Sov. Phys. JETP 37, 823 (1973)].
Speckled images of a binary broad band light source (600-670 nm), generated by randomized reflections or transmissions, were used to reconstruct a binary image by use of multi-frame blind deconvolution algorithms. Craft store glitter was used as reflective elements. Another experiment used perforated foil. Also reported here are numerical models that… (More)
We have predicted and observed an optical analogue of aerodynamic lift, in which a cambered refractive object with differently shaped top and bottom surfaces experiences a transverse lift force when placed in a uniform stream of light. A semi-cylindrical rod is found to automatically torque into a stable angle of attack, and then exhibit uniform motion. We… (More)
Optical vortices are singularities in phase fronts of optical beams. They are characterized by a dark core in the center and by a helical wave front. Owing to azimuthal components of wave vectors, an optical vortex carries orbital angular momentum. Previously, optical vortices were studied only in coherent beams with a well-defined phase. The object of this… (More)
We believe that the effect observed by Xing et al. is essentially cross-phase modulation. It was inaccurately identified as self-bending of light, which is a self-action effect well known in the literature. This Comment addresses an observed effect that we believe has been inaccurately identified by Xing et al. 1 The reported effect is not self-bending, as… (More)
The nonlinear refractive-index (n(2)) spectrum of ZnSe near the band gap (lambda(gap) approximately 450 nm) at 77 K was measured for the first time to our knowledge by using self-bending of a pulsed laser beam. The maximum nonlinearity, n(2) approximately 1.9 x 10(-8) cm(2)/W, measured by us is anomalously large, which cannot be explained by conventional… (More)
Continuous-wave self-deflection of an asymmetrical laser beam, with a deflection angle up to eight diffraction widths, and strong attenuation of the on-axis radiation were achieved in a short sodium-vapor cell. We determined that the nonlinear refractive index Deltan varied almost linearly with intensity I, Deltan approximately n(2)I, with n(2) ~ -10(-7)… (More)