A finite-difference time-domain formalism for second-order nonlinear effects

An approach is proposed to incorporate second-order nonlinear effects into finite-difference time-domain simulations, which allows dispersion to be included for all 18 elements of the second-order nonlinear susceptibility tensor. The developed approach is implemented to investigate optical rectification and difference frequency generation in a bulk LiNbO₃ crystal. This method allows for the generalized finite-difference time-domain investigation of second-order nonlinear effects.