Learning Forum

[jasper]

Hello,

when calculating the dispersion in a waveguide using the script and following the instructions in this post (Sweep analysis for dispersion calculations – Ansys Optics), I get this result:

Those Peaks at 1.7-1.9µm have values of a few million, which is obviously wrong. The geometry is a SiN core (1400nmx850nm) with SiO2 cladding. What could cause this problem? I have fitted the material index with a 4th-order polynomial. I get the same wrong result for a waveguide width of 1600nm.

[Guilin Sun]

This is most-likely due to material fitting. Please fit the material for the desired wavelength range.

Since you are using script to get result, you can try to fit neff vs omega. Once you have analytical expression, you can get the derivative easily.

[jasper]

 

I have already fitted the material like this.

I also use only 4 coefficients to avoid unecessary curvature. Instead, when I sweep from 1.2µm instead of 1µm wavelength, the peaks disappear.