Optical limiting materials in the high-fluence regime

Summary form only given. The aim of the present paper is to identify some of optical processes that occur in the high-fluence regime. Optical limiting, nonlinear transmission, and z-scan measurements are reported in the visible region of the spectrum. The contributions of nonlinear absorption and nonlinear refraction to the limiting were separately determined. Modeling the nonlinear absorption results with three-, four-, and five-level models suggest that both exciton-exciton annihilation and higher-order nonlinear absorption processes make important contributions to optical limiting. The higher order processes were found to contribute substantially to limiting in lead tetrakis(cumyl-phenoxy)phthalocyanine.