Fan Yang

Thank you for your response! Here are my settings for the mesh accuracy and PML thickness in FDTD. I ran it long enough to reach the autoshutoff min. For RCWA, I tried different number of k-vectors ranging from 5 to 300, but I found every time it gives me different result.

As for the difference, it's about the diffraction efficiency. They can have 30% difference on the first order. I also found that if I simulate 2 periods of the grating, FDTD gives me almost the same value as 1 period, but RCWA gives me different values, and it also varies depending on the number of k-vectors. So I think the problem is most probably coming from RCWA. I also attached a table summarizing all the results.

Thank you!