Numerical modeling of z-scans of thick nonlinear absorbers.

A numerical scheme for modeling of z-scans with samples ranging from thin samples to beyond the thick sample limit was introduced in our previous work (A. Eriksson et ai., J. Opt. Sec. Am. B15, pp. 810-816, 1998). The method relies on a multilayer approach, where all layers are treated as independent, and may have different linear and nonlinear optical properties. The theoretical scheme can be used for irradiance as well as fluence dependent absorbers. It allows for an arbitrarily shaped aperture in front of the detector. Here the method is tested and compared with the results of analytical thick sample theory and previously published numerical simulations. Ways of optimizing the performance of an optical limiting device are modeled and discussed. Preliminary experimental z-scan results of both thin and thick sample chloroaluminum phthalocyanine were analyzed.