Polar solvents mediated third-order nonlinear optical features of acid green 16 dye

The objective of this study is to examine the third-order nonlinear optical (NLO) characteristics of acid green (AG) 16 dye dissolved in polar liquids, including methanol, ethanol, DMF, and DMSO. The study employed a Z–scan instrument using a low power laser as the excitation source, operating at a wavelength of 650 nm with a power output of 5 mW. The closed-aperture (CA) and open-aperture (OA) Z–scan experiments were applied to estimate the nonlinear indices of refraction (n₂) and nonlinear coefficient of absorption (β) of AG 16 dye in polar liquids. AG 16 dye demonstrates both saturable absorption and reverse saturable absorption in the OA Z–scan results, due to negative and positive NLO absorption coefficients. The dye sample proves a self-defocusing NLO refractive index while operating under low-power conditions. The third-order NLO susceptibility (χ³) of AG 16 dye in various polar liquids are calculated to be the order of 10^–6 esu. The solvent spectral parameters effect on χ⁽³⁾ of AG 16 dye is studied by multi-parameter scale. The results provide a significant insight into the properties of AG 16 dye, suggesting a potential material for future NLO applications.