The nonlinear light absorption of aqueous and alcohol solutions of methylene blue has been studied by the method of Z-scanning under continuous pumping. It is shown that the mechanisms of optical nonlinearity of these solutions vary depending on the dye concentration and type of solvent. The dependence of the amplitude of nonlinear absorption of dye molecules on the concentration and sign of the surface charge of gold and silver nanoparticles in solution is revealed. Mathematical models of optical nonlinearity for concentrated and diluted solutions of dye molecules are considered; in the latter case, the influence of plasmon nanoparticles on the nonlinear optical characteristics of methylene blue solutions is taken into account.

通过连续泵浦下Z扫描法研究了亚甲基蓝水溶液和醇溶液的非线性光吸收。结果表明，这些溶液的光学非线性机制随染料浓度和溶剂类型的不同而变化。揭示了染料分子非线性吸收幅度对溶液中金和银纳米颗粒表面电荷的浓度和符号的依赖性。考虑了染料分子浓缩和稀释溶液光学非线性的数学模型；在后一种情况下，考虑了等离子体激元纳米颗粒对亚甲基蓝溶液非线性光学特性的影响。