Self-induced mode transformation in nonlocal nonlinear media

We report on the first experimental observation of self-induced optical mode transformations in nonlocal nonlinear media. We show that the quadrupole Hermite-Gaussian mode experiences complex nonlinear dynamics in a nematic liquid crystal, including powe

Momentum transfer in a standing optical vortex

A field superposition of singular beams incident on, and then reflected from a mirror has been investigated. It was demonstrated that the standing optical wave, which contains a vortex, possesses an orbital angle momentum where the energy flux circulates only in the azimuth direction of the beam. We show in this paper that the standing light wave containing the optical vortex transfers angular momentum to a substance located in the field of the vortex without moving the substance in the azimuth or radial directions. This property of the standing vortex present an opportunity to form the three-dimensional optical traps, gasdynamic and hydrodynamic vortices, in a localised volume by a direct transfer of the orbital angular momentum from the optical vortex.Comment: English has been corrected; a second address entered; Eq.(13) and (14) corrected. 11 pages, including 1 figur

Counterpropagating nematicons in bias-free liquid crystals

We experimentally investigate the interaction of two counterpropagating spatial optical solitons (nematicons) in bias-free nematic liquid crystals. We demonstrate the existence of vector solitons composed of two nematicons propagating in opposite directions and analyze their stability versus relative distance and input power.We observe the dynamic instability of two counterpropagating nematicons in the form of time-dependent splitting and spatial entanglement

Nonlinear propagation and quasi self-confinement of light in plasmonic resonant media

We study nonlinear propagation of light in colloidal suspension of metallic nanoparticles, in the regime of particles surface plasmon resonance. We show that the propagation exhibits features typical for purely defocusing media and the observed spatial confinement is not a real self-trapping, as for solitons, but rather than is caused by the phase modulation of the beam via nonlocal defocusing nonlinearity. We also show that the light-induced refractive index change in the suspension leads to stabilization of structured light beams. In particular, we demonstrate a stable nonlinear propagation of bright ring beams with complex states of polarization, including practically important radial and azimuthal states.Qatar National Research Fund (grant # NPRP 9-020-1-006). Y.S-R. acknowledges support from CONACyT and Australian and Mexican Academies of Science for Ph.D. internship grant

Magnetically controlled negative refraction of solitons in liquid crystals

We demonstrate magnetically controlled refraction of a spatial soliton forming beam at the interface between an isotropic material and a uniaxial nematic liquid crystal, in which the optical axis together with an incident beam can make any desired angles with the interface. Depending on the direction of the applied magnetic field and incident beam angle, the refracted soliton forming beam experiences either positive or negative refraction.The work was supported by the Australian Research Council and the Qatar National Research Fund (Grant No. NPRP 9-020-1-006)

Magnetic routing of light-induced waveguides

Among photofunctional materials that can be employed to control the propagation of light by modifying their properties, soft dielectrics such as nematic liquid crystals (NLCs) stand out for their large all-optical response. Through reorientation, the molecular distribution of NLCs can be modified by the electric field of light, permitting functional operations and supporting self-localized light beams or spatial optical solitons. To date, the generation and routing of such solitons have been limited by the boundary conditions employed to tailor the properties of NLCs in planar cells or capillaries. Here we report on spatial solitons in bulk NLCs with no lateral anchoring, where the application of an external magnetic field effectively controls the direction of propagation and the angular steering of the self-trapped wavepackets. Our results entail a completely new approach to the routing of self-localized beams and light-induced waveguides in three dimensions, without the usual limitations imposed by transverse boundary conditionsThe ANU and TAMQ authors acknowledge the support from the Australian Research Council and the Qatar National Research Fund (grants NPRP 9-020-1-006). G.A.’s work was funded by the Academy of Finland through the Finland Distinguished Professor grant no. 282858

Generation of optical bottle beams by incoherent white-light vortices

We generate experimentally optical bottle beams from incoherent double-charge white-light vortices, and show that their parameters can be efficiently controlled by varying the beam focusing conditions

Selective trapping of multiple particles by volume speckle field

We suggest a new approach for selective trapping of light absorbing particles in gases by multiple optical bottle-beam-like traps created by volume speckle field. We demonstrate stable simultaneous confinement of a few thousand micro-particles in air with a single lowpower laser beam. The size distribution of trapped particles exhibits a narrow peak near the average size of an optical speckle. Thus, the speckleformed traps act as a sieve with the holes selecting particles of a similar size