I am designing a chirped Bragg grating. The problem is that I need very thin meshes to get the perfect results but when I do over meshing, the results become worst. I did some changes like changing the parameters of FDTD (stabilize) or decreasing the stability factor up to 0.5 to decrease the reflection, But it did not work at all. I have result with and without mesh. I was wondering if you can help me to get the perfect answer.