Guilin Sun
Ansys Employee
It is grating structure so the back-and-forth reflection is strong. in time domain method, you will need to set sufficient simulation time to let the intensity to accumulate, therefore you will also need to significantly reduce autoshutoff min.
From the results at 1.525~1.575um it indicates that the simulation time is not long enough, so the Fourier transform has ripples. so please increase simulation time and reduce autoshutoff min. You can set long enough simulation time, and set "check points" so you can compare results at different autoshutoff min: