Comparative analysis of multi-wave mixing and measurements of the higher-order nonlinearities in resonant media

The features of degenerate multi-wave mixing in resonant media (dye solutions) have been studied theoretically and experimentally. It has been demonstrated that thermal nonlinearity due to the induced absorption from the excited level contributes significantly to the efficiency of four-wave mixing, but results in lower efficiency of higher-order interactions. The measurement results obtained for the energy efficiency of four-, six- and eight-wave mixing enable calculations of the third-, fifth- and seventh-order nonlinear optical susceptibilities, respectively. Experimentally, the method proposed for measurements of the higher-order nonlinearities has been realized with the use of the multi-wave mixing at second harmonic λ = 532 nm of monopulse YAG:Nd³⁺ laser radiation in a Rhodamine 6G dye solution. The ratios ∣χ⁽⁵⁾∣/∣χ⁽³⁾∣ and ∣χ⁽⁷⁾∣/∣χ⁽⁵⁾∣ are determined to be of the order of 10⁻⁵ cm³/erg.