Large silicon Nitride ring simulation

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To help us solve your issue as quickly as possible, please provide the following information:

1. What device are you trying to simulate? Include diagrams if available.

I am trying to simulate the coupling region of silicon nitride ring with radius of 60um

2. What results are you trying to obtain? Be as specific as possible.

I am trying to obtain S-parameters and transmission

3. Description of the problem or issue.

Getting transmission greater than one and consequently the S-parameters are not correct

4. Lumerical product and software version.

FDTD, 2019b

5. Please attach your simulation files, including any logs.
Si3N4_Ring.fsp (3.4 MB)

Hello @SIE,

This could indicate that the source is not being injected properly, possibly because the port spans are too small:

I would recommend you increase the spans of your port objects so the mode fields reach close to zero at the edges of the source.

I hope this helps. Let me know if you have any questions.

Thanks @kjohnson for the feedback,

I increased the spans of the ports but still I got T>1 as attached