The Investigation of the Effects of Media Polarity and Concentration on the Third Order Nonlinear Optical Properties of Azo Dye Solutions

In this paper, Z-scan technique was used for investigating the effects of media polarity and concentration on the third order nonlinear optical properties of azo dye solutions. In this case, a cw mode laser at the wavelength of 650 nm and output power of 70 mW was used as a single excitation source. The experimental results indicate that reverse saturable absorption characteristics of the sample depend highly on the media polarity and concentration of dye solutions. According to the findings, by increasing the concentration of dye solutions, the nonlinear absorption coefficient of azo dye is increased in three different groups of solvents. High nonlinear absorption coefficients were observed in solvents with high hydrogen bond acceptor ability. Therefore, by selecting a proper solvent media and setting the concentration of dye solutions, a simple method for controlling the nonlinearity of selected azo dye was provided. Moreover, the selected azo dye with high nonlinearity and reverse saturable absorption characteristics can be used in optical devices.