S.H. Mousavi

Determination of Temperature Dependence of Kerr Constant for Nematic Liquid Crystal

Nematic liquid crystals are the preferred materials for linear and nonlinear optics, where frequently required photosensitivity is provided by appropriate doping. This investigationis concerned with the determination of the Kerr constant of nematic liquid crystal (9CHBT). The temperature dependence of the Kerr constant B for azo dye doped nematic liquid crystalshas been studied. The sample has a positive Kerr constant which increases with decreasing of temperature. The linear dependence of the Kerr constant on (T – T*)−1is found to be ingood agreement with the predications of the Landau-de Gennes model.

Characterization of Optical Nonlinearity in Dye-Doped Nematic Liquid Crystal and the Effect of AC Voltage on Its Behavior

In this paper the nonlinear refractive index, n2, of an azo dye (Sudan III) doped nematic liquid crystal was measured at low laser power using closed aperture z-scan and moiré deflectometry techniques. The positive sign indicates a self-focusing effect that accrued in the sample. The nonlinear refractive index n2 is in order of 10−6 cm2/W with z-scan method. This observation is found to be in good agreement with the moiré deflectometry model. The optical response of the nematic liquid crystals was strongly enhanced by a small amount of dye impurities (Sudan III). Also the effect of external applied AC voltage on the nonlinear refractive is studied.