Guilin Sun
Ansys Employee

Unfortunately, FDTD and MODE material database do not have any thermal data. and they cannot directly simulate the thermal change, even you have the  thermo-optic coefficient. What they simulate is the actual refractive index either from the material database, or perturbation simulated from HEAT. Please refer

https://optics.ansys.com/hc/en-us/articles/360042833673-Thermally-tuned-waveguide-FDE-

 

If you need, you will have to search literature to get the  thermo-optic coefficient.