Measurements of the higher-order nonlinear optical susceptibility with the use of frequency-degenerate and -nondegenerate multiwave mixing

For the purpose of determining the higher-order nonlinear optical susceptibility the diffraction method based on investigation into the Fourier-expansion spatial components for the anharmonic grating of the refractive index has been used. Comparison between the experimental and theoretical data makes it possible to relate unambiguously the energy efficiency of multiwave mixing to the nonlinear susceptibility. Efficiency of the proposed mixing patterns has been tested experimentally on the basis of dye solutions in conditions of pulsed laser excitation. 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 multiwave mixing of monopulse Nd:YAG laser radiation in the solution of polymethine and Rhodamine 6G dyes.