Measurements of nonlinear optical refraction and absorption in an amino-triazole push-pull derivative by a vectorial self-diffraction method

We present a method for measuring the magnitude and sign of the nonlinear refractive and absorptive coefficients in isotropic media based on vectorial two-wave mixing. The technique consists of the measurement of the self-diffracted signals as a function of the angle between the linear polarizations of two input pulses. The technique was used to investigate the nonlinear optical response of three amino-triazole derivatives in solution, using nanosecond pulses at 532 nm. For these samples the results show that nonlinear refraction is isotropic, and that nonlinear absorption is present. Input-output experiments show nonlinear absorption consisting of a combination of saturation and induced absorption. A three-level model for the nonlinear absorption was used to explain the experimental results.