Single-beam Z-scan measurement of the third-order optical nonlinearities of azo dyes.

Organic dyes are very attractive optical materials for photonics and biophotonic applications. To quantitatively characterize their third-order nonlinear coefficients we have performed the experiments on two different azo dyes using a diode-pumped Nd:YAG laser at 532 nm. The |chi(3)| is of the order of 10(-6) esu. The relative contributions from nonlinear absorption (NLA) and nonlinear refraction (NLR) are dependent on the chemical structure and linear absorption of the dyes.