Using the “index perturbation” material in FDTD Solutions and MODE Solutions, users can model the effect of temperature variation on the refractive index of a material. The index perturbation material can use a base material (silicon in the screenshot below) and then perturb the index using one of the two available options:
Linear model: As seen on the left side of the screenshot, users can define a linear dependency on temperature by defining a fixed gradient.
Nonlinear model: Users can also use the option on the right side (screenshot) and choose to upload a table of values that record the change (delta_n and delta_k) in index as a function of temperature. If the material of interest has a nonlinear dependency then this will be the way to go.