Non linearly induced self waveguiding structure in dye doped nematic liquid crystals confined in capillaries

We report on experiments dealing with the propagation of a collimated laser beam in a dye doped nematic confined in a capillary of optical fiber size. The nematic is aligned in a such a way that the source beam is self focused. The behavior of the beam - focusing, multifocus regime, filamentation and undulation - already observed in larger cylindrical geometry and pure nematic is shown here to be reproduced in the dye doped medium, at much lower powers. Another feature is reported here: a stable regime looking like a waveguide appears in certain conditions, in which the beam to propagate in a narrow tube. This regime is simply modeled in terms of saturated reorientation of the nematic

Route to nonlocality and observation of accessible solitons

We develop a general theory of spatial solitons in a liquid crystalline medium exhibiting a nonlinearity with an arbitrary degree of effective nonlocality. The model accounts the observability of "accessible solitons" and establishes an important link with parametric solitons.Comment: 4 pages, 2 figure

Soliton mobility in nonlocal optical lattices

We address the impact of nonlocality in the physical features exhibited by solitons supported by Kerr-type nonlinear media with an imprinted optical lattice. We discover that nonlocality of nonlinear response can profoundly affect the soliton mobility, hence all the related phenomena. Such behavior manifests itself in significant reductions of the Peierls-Nabarro potential with increase of the degree of nonlocality, a result that opens the rare possibility in nature of almost radiationless propagation of highly localized solitons across the lattice.Comment: 16 pages, 4 figure

Observation of optical spatial solitons in a highly nonlocal medium

We report on the observation and quantitative assessment of self-trapped pulsating beams in a highly non-local nonlinear regime. The experiments were conducted in nematic liquid crystals and allow a meaningful comparison with the prediction of a scalar theory in the perturbative limit, while addressing the need for beyond-paraxial analytical treatments.Comment: 16 pages, 3 figure

Self-confined light waves in nematic liquid crystals

The study of light beams propagating in the nonlinear, dispersive, birefringent and nonlocal medium of nematic liquid crystals has attracted widespread interest in the last twenty years or so. We review hereby the underlying physics, theoretical modelling and numerical approximations for nonlinear beam propagation in planar cells filled with nematic liquid crystals, including bright and dark solitary waves, as well as optical vortices. The pertinent governing equations consist of a nonlinear Schrödinger-type equation for the light beam and an elliptic equation for the medium response. Since the nonlinear and coupled nature of this system presents difficulties in terms of finding exact solutions, we outline the various approaches used to resolve them, pinpointing the good agreement obtained with numerical solutions and experimental results. Measurement and material details complement the theoretical narration to underline the power of the modelling

«Nanoparticules fonctionnalisées pour l’optique»

National audienc

From bulk Janossy effect to nonlinear self waveguiding or spatial soliton in dye doped liquid crystals

Invited Publicatio