Fryad Z. Henari

NONLINEAR REFRACTIVE INDEX MEASUREMENTS OF CURCUMIN WITH CW LASER

We report on the measurements of the nonlinear reflective index coefficient for curcumin at three different wavelengths using a Z-scan technique. This material is found to be a new type of natural nonlinear media. It shows a large negative nonlinear refractive index of the order of 10–6 cm2/W. The origin of the nonlinearity was investigated by comparison of the formalism that is known as the Gaussian decomposition model with the thermal lens model. The nonlinear refractive index was found to vary with intensity and reveals that curcumin can be a promising material for optical limiting.

OPTICAL LIMITING BEHAVIOR OF BROMOPHENOL BLUE AND ITS DEPENDENCE ON pH

The nonlinear properties and optical limiting performance of Bromophenol indicator solution were investigated using continuous wave laser beam at 488 nm and 514 nm. A z-scan technique was used to measure the nonlinear refractive index. The optical limiting was investigated by monitoring the output transmission through the samples at different concentrations and at different pH values. The results show the dependence of the optical limiting threshold on concentration as well as on the pH values of the solution. The investigation shows that bromophenol blue is a potential candidate for optical limiting. Results also show that the optical limiting values can be used as a pH indicator.

NON-LINEAR REFRACTIVE INDEX MEASUREMENT OF (2E)-3-[4-(DIMETHYLAMINO)PHENYL]-1-(2,5-DIMETHYLTHIOPHEN-3-YL)PROP-2-EN-1-ONE AND (2E)-3-(3,4-DIMETHOXYPHENYL)-1-(2,5-DIMETHYLTHIOPHEN-3-YL)PROP-2-EN-1-ONE

We report results from investigations of the nonlinear refractive index and nonlinear absorption coefficient of (2E)-3-[4-(Dimethylamino)phenyl]-1-(2,5-dimethylthiophen-3-yl)prop-2-en-1-one and (2E)-3-(3,4-Dimethoxyphenyl)-1-(2,5-dimethylthiophen-3-yl) prop-2-en-1-one using Z-scan technique with a continuous wave (cw) laser at wavelengths 488 nm and 514 nm. The nonlinear refractive index and nonlinear absorption coefficient of both samples were evaluated. The origin of the nonlinear effects was discussed. Optical limiting based on light induced nonlinear refractive index variation is demonstrated. The limiting thresholds were estimated for both samples. The results suggested that these materials offer promise as candidates for optical limiting and optical devices in the low power regime.