Comprehensive numerical model is developed to investigate the characteristics of FWM in silicon nanowire waveguides. The model is based on a set of coupled nonlinear Schrodinger equations describing the propagation of the pump, signal, and converted waveform through the waveguide. The effect of dispersion, free-carrier absorption, two-photon absorption, and state of polarization are taken into account. Analytical solutions are also deduced from the model under simplified conditions to get approximated description for the key roles played by various system parameters. Both numerical and...