Spatially incoherent modulational instability in a non local medium

We investigate one-dimensional transverse modulational instability in a non local medium excited with a spatially incoherent source. Employing undoped nematic liquid crystals in a planar pre-tilted configuration, we investigate the role of the spectral broadening induced by incoherence in conjunction with the spatially non local molecular reorientation. The phenomenon is modeled using the Wigner transform.Comment: 13 pages with 4 figures included. To be published in Laser Physics Letter

Nonlinear Optical Effects in Nematic Liquid–Crystal Films in the 1.55 mm Spectral Region

We have studied the optical nonlinearities of nematic liquid crystals in the near IR communication spectral region [1.55 µm]. The origins of the refractive index changes are thermal indexing effect and director axis reorientations. Very large refractive index and phase modulation of several ?'s can be generated with mW laser power in micron thick dye-doped nematic liquid crystal films

Principles of optical engineering

xii, 311 p. : il.; 26 cm

Optical Holographic Grating Formation in Dye- and Fullerene-Doped Liquid Crystalline System

The nonlinear optical properties of nematic liquid crystal films doped with dyes of fullerene C60 are studied. Nematic liquid crystals were doped with azo-dyes, and tested for their optical storage capabilities. An electro-optical holographic storage grating effect is observed in C60-doped nematic liquid crystal films. The effect is attributed to molecular axis reorientation caused by the combination of an applied DC field and an optically induced DC space charge. The observed nonlinear sensitivity of the films is larger than that of other materials studied

Dye-doped Photorefractive Liquid Crystals for Dynamic and Storage Holographic Grating Formation and Spatial Light Modulation

The basic mechanisms of photo-induced space charge field formation, director axis re-orientation, and refractive index changes in fullerene C60- and dye-doped nematic liquid crystals films are presented. In particular, in aligned methyl-red-doped nematic liquid crystal film, we observe a nonlinear index change coefficient as high as 10 cm2/W, associated with purely optically induced liquid crystal director axis re-orientation. Experimental observations of dynamic and high-resolution storage holographic grating formation, two beam coupling with gain of nearly 3000 cm-1, optical limiting action at nanowatt cw laser power, and incoherent-coherent image conversion at μW/cm2 light intensity level are discussed