Differences between simulations results in varFDTD and FDTD

- June 9, 2023 at 1:40 pm
  
  Zehava Bernstein
  Subscriber
  
  I tried to make simulations of a structure with slotted discs (picture attached).
  Because the structure is planned to be 100 microns long, I thought to simulate it in varFDTD.
  In order to test the reliability of varFDTD, I made comparisons in a simple simulation between varFDTD and FDTD and I got completely different transmission results.
  structure (top view):
  FDTD transmission:
  varFDTD transmission:
  
  Has anyone encountered anything similar? Why are there such large differences between the identical simulations?
  Is there anything I need to configure differently? Could it be that the structure is not compatible with varFDTD?
  
  Thanks,
  Zehava
- June 9, 2023 at 4:48 pm
  
  Guilin Sun
  Ansys Employee
  
  No they are not identical in the discrete mesh even though the device configuration is the same. It might be due to shorter simulation time. Have you checked the mode source and the polrization is exactly the same?
  Please reduce the autoshutoff min, increase the simulation time, and make sure the mode is the same. The result from varfdtd looks incorrect. Make sure the reference green point is on the waveguide core.