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.