Simulations and experiments on self-focusing conditions in nematic liquid-crystal planar cells

Abstract

Owing to the nonlinear effect of optical field-induced director reorientation, self-focusing of an optical beam can occur in nematic liquid crystals and an almost diffraction-compensated propagation can be observed with milliwatts of light power and propagation lengths of several millimeters. This opens the way for applications in all-optical signal handling and reconfigurable optical interconnections. Self-focusing of an optical beam in nematic liquid-crystal cells has been studied experimentally and by means of numerical simulation. The relationships between bias voltage, cell thickness and required optical power have been examined, thus allowing the determination of the most favorable conditions for soliton-like beam propagation.

Reply to “Comment on ‘Spatial optical solitons in highly nonlocal media”'

“…Our results establish a good quantitative agreement between experimental data and the modified SMM [2], as recently shown in [13]. Finally, the results from our group have been experimentally validated by several groups [14][15][16][17][18][19][20][21][22][23].…”

“…In the introduction of [4] Ouyang et al state: "On the other hand, even though a convenient method has been introduced in Refs. [3,5,13,14] to study the propagation of light beams in the strongly nonlocal case or even in the sub-strongly nonlocal case, to employ this method efficiently the nonlocal response function must be twice differentiable at its center. As will be shown this method cannot deal with the nonlocal case of an exponential-decay type nonlocal response function that is not differentiable at its center".…”

Observation of out-coupling of a nematicon

“…They have been generated in these materials by either thermal nonlinearities [3] or reorientational nonlinearities [4][5][6]. Due to the molecular reorientation under the influence of a linearly polarized optical electric field, the refractive index is higher where the optical intensity is higher.…”

“…To the best of our knowledge, in all the reported experiments on nonlinear waveguiding in liquid crystals, the beam propagation in the cell is observed either via the light scattered by the liquid crystal [4][5][6][7][8][9][10] or via indirect observation by visualization of the self-induced waveguide [7,13]. In these measurements, the light beam (or the material properties) can only be observed in the plane parallel to the glass surfaces, while no information is available along the thickness of the cell.…”

Optically-driven switching of a planar nematic liquid crystal cell with parallel rubbing

“…In liquid crystals such nonlinearities are already noticeable for milliwatt powers of an optical beam [2]. Optical reorientation in liquid crystals is commonly used for the generation of spatial optical solitons [3][4][5][6].…”