Learning Forum

[iqnlo]

Hi there

I am doing mode convergence test for my own design of edge coupler. But I found that the mode didn't converged.

I'm using the codes from this page: Convergence testing process for EME simulations – Lumerical Support

First of all, I applied this script on your official edge coupler: Edge coupler – Lumerical Support

[Kyle]

It's possible that you're using too many modes, as discussed in this video: Convergence Testing - Too Many Modes. If you set the energy conservation to "none" and turn off the CVCS method, what does the convergence test look like?

[iqnlo]

Hi! I tried to turn off the CVCS but the S12^2 dropped greatly. If I use the CVCS to simulate the taper area, the S12^2 is always around 90%-99% when doing the propagation sweep.
However, if I use the "none" to simulate the taper area as you said, the sweeping result is around 50%.

[iqnlo]

In the tutorial, I remember that using CVCS is always recommended for the taper shaper structures. There should only be slight difference between the "none"and "CVCS" because of the staircase effect.
But in my case, 50% loss in included when I change the CVCS to none