Reply To: Diverging simulation when going from long to short wavelength

[Daniel Marchant]

Hi Anita, thank you for your quick reply.This is a single wavelength simulation (simulation bandwidth of 0.3 um which is the standard set by Lumerical FDTD, I also tried reducing this to 0.1 um but that did not resolve the issue). The materials used are Silicon Nitride (for the waveguide) and silicon dioxide (for the cladding).

I think you may be correct about the issue being related to the material fitting, but I am not sure exactly how this is causing the issue. As I mentioned, the simulation runs fine for a longer wavelength and I use similar values for the fit tolerance, number of fitting coefficients and the fitting range. 

I have attached some images from the movie monitor that show the issue.

Kind regards,

Daniel