Nonlinear Optical Features of Phenol Red Dye in Different Solvent Media Using Z-scan and Density Functional Theory.

This study extensively discusses the nonlinear optical properties of phenol red dye, which is commonly used as an indicator dissolved in various solvents. The fluorescence analysis indicates that the phenol red dye exhibits excitation in the red region of the spectrum. Z-scan tool is employed to evaluate the third-order nonlinear optical parameters of phenol red dye in polar liquids. Z-scan study accomplished by using a diode laser with 405 nm wavelength and an output intensity of 741 W/cm. Both closed and open aperture Z-scan techniques yield significant values for the nonlinear refractive index and absorption coefficient of phenol red dye. The order of nonlinear refractive index and absorption coefficient of phenol red dye are found to be of 10⁻ cm/W and 10⁻ cm/W, respectively. A large second-order hyperpolarizability of phenol red dye is observed, with a value on the order of 10⁻ esu. The density functional theory studies at the B3LYP/6-311 +  + G(d,p) level provide the linear polarizability (α), first-order hyperpolarizability (β), and second-order hyperpolarizability (γ) values in ethanol, methanol, DMF, and DMSO, supported by experimental results. Multi-parameter scale is applied to assess the impact of solvents on phenol red dye and implies that both specific and non-specific interactions contribute to the resulting nonlinearity in phenol red dye.