Experimental study of the influence of solvents on the optical nonlinearity of methyl red

The absorption spectra of methyl red (MR) dissolved in methanol, ethanol, dimethyl sulfoxide, and hexane were measured. It was found that the peaks of the absorption spectra of MR solutions shifted toward shorter wavelengths with increasing solvent polarity. Using the Z-scan method, the nonlinear optical properties of the four kinds of MR solutions were determined at wavelength 441.6 nm. The effective nonlinear indexes of refraction (n2) of MR solutions increased with the increasing thermo-optical coefficients of the solvents. In addition, the optical limiting effects of the MR solutions were investigated at 441.6 and 535 nm, and the results indicate that they possessed strong optical limiting effects.