FIT‐TD Simulation of 2nd Order Instantaneous Non‐linear Materials using Iterative Methods Available to Purchase

We present a strategy to perform time domain updates of the electromagnetic fields in instantaneous $χ(2)$ non‐linear materials in the finite integration technique (FIT). The extended FDTD‐like algorithm introduces an internal inverse material relation to calculate the fields. This relation can be implemented in various ways, enhancing performance and/or accuracy. The resulting algorithms are tested with a numerical example consisting of a periodically poled ridge waveguide, where the second harmonic amplitude is obtained by a modal analysis.