BORTOLOZZO , Umberto

We show experimentally that large matrixes of localized structures can be stored as elementary pixels in a nematic liquid crystal cell. Based on optical feedback with phase modulated input beam, our system allows to store, erase and actualize the localized structures in the matrix.

We show that the Talbot effect can be used to increase the gaib of two-wave mixing in a stack of this nonlinear media. We demonstrate that a large gain enhancement is achieved for a new nonlinear elements, provided that they are placed at distances that satisfy Talbot recurrences.

We study the Faraday instability in an elongated rectangular cell and for a range of the forcing frequency for which two nearly degenerate modes enter in competition. We investigate the stability properties of the two modes and we show that they can either coexist in a bistable way or give rise to a mixed mode. We develop a simple model based...

International audience

We show that the Talbot effect can be used to increase the gaib of two-wave mixing in a stack of this nonlinear media. We demonstrate that a large gain enhancement is achieved for a new nonlinear elements, provided that they are placed at distances that satisfy Talbot recurrences.

In a nonlinear optical experiment we report a unique class of localized structures, which appears as localized peaks of a pattern nucleating over another pattern. We show that this occurs when the system is driven through three pattern branches of solutions, accompanied by the appearance of localized peaks with two different amplitudes....

International audience

International audience

In a photorefractive liquid crystal light valve, acting as a Kerr-like nonlinear optical medium, we show the appearance of optical patterns induced by a single mirror feedback. The spatial wavelength of the patterns scales with the distance between the mirror and the valve and the contrast of the patterns decreases for decreasing this distance....

Liquid-crystal (LC) optically addressable spatial light modulators (OASLMs) allow control of the phase and amplitude of optical beams. By performing wave mixing in an OASLM, we show that coherent phase detection can be achieved for light beams passing through highly scattering media, such as foam layers with several cm thicknesses. Thanks to...

Ongoing research on chiral liquid crystals takes advantage of the peculiar behavior of twisted structures subject to curvature. We demonstrate the fine tunability of the characteristics of the bandgap of a cholesteric structure in which the orientation of the helix axis spatially changes. To date, the spectral resolution of the order of 6 nm,...

International audience

International audience