A method for determination of real and imaginary parts of third-order NLO susceptibility in solid solutions

A technique for the experimental determination of the modulus and the phase of third-order nonlinear optical susceptibility for a molecule solubilized in an isotropic matrix is proposed. The technique requires experimental determination of the concentration dependence of NLO susceptibility. Few examples of the theoretical predictions of the concentration dependence of solution susceptibility are computed and presented. The technique is applied for a deoxyribonucleic acid (DNA)–surfactant complex, doped at different concentration with Rhodamine 610 luminophore. The method allows, from the concentration variation of measured NLO susceptibility, to determine that of matrix and solute molecule as well as its phase.

► Method for cubic susceptibility phase determination in solid solution is proposed.
► This method is applied for DNA–CTMA complex doped with Rhodamine 610 at several amounts.
► A complex NLO susceptibility of studied chromophore is observed.
► This method allows also determination of nonlinear susceptibility of host and solute molecules.