Unified model for a nonlinear pulse propagation in composites and optimization of THz generation

We describe a unified numerical model which allows fast and accurate simulation of nonlinear light propagation in nanoparticle composites, including various effects such as group velocity dispersion, second- and third-order nonlinearity, quasi-free-carrier formation and plasma contributions, exciton dynamics, scattering, and so on. A developed software package, Simulator of Light Propagation in Composites (SOLPIC), is made available for the community. Using this model, we analyze and optimize efficient generation of terahertz (THz) radiation by two-color pulses in ZnO-fused-silica composite, predicting an efficiency of 3%. We compare the role of various nonlinear effects contributing to the frequency conversion and show that the optimum conditions of THz generation differ from those expected intuitively.