material Au (Gold) – CRC uses a fit range that does not fully overlap the simulation bandwidth

- December 8, 2021 at 4:34 pm
  
  photon
  Subscriber
  
  In the simulation and memory report in FDTD, I am receiving the warnings as below:
- December 9, 2021 at 12:42 am
  
  Guilin Sun
  Ansys Employee
  
  This might be the 2nd report of this issue however we have not duplicated this.
  Please check the material fitting and make sure the fitting range is the source bandwidth; and make sure the FDTD settings are not modified accidently. Suggestions:
  1: open a new project file, copy and paste all the objects excluding FDTD by Ctrl^C and Ctrl^V, add FDTD and modify the xyz spans accordingly, and boundary conditions only, then test to see if it disappears
  2: simplify the simulation file with two materials: Au and SiO2, and test. if problem still exists, please give your settings so I can test, in particular the source setting (spectrum), material fittings and FDTD Advanced settings
- January 16, 2022 at 2:39 pm
  
  spacelover17
  Subscriber
  
  I was having the same issue. What settings would you like to see? I could also email you my simulation file itself, tested with the two suggestions you provided.
- January 17, 2022 at 4:56 pm
  
  Guilin Sun
  Ansys Employee
  
  Please just check the actual material fitting. As long as it is the same range as you set, it should not affect the final result. Yes, please send us a email if you can.
- March 20, 2022 at 9:17 am
  
  amnonjw
  Subscriber
  
  Hello I recently also found this issue with the fitting and the bandwidth. The images below show the material fit and simulation warning.
  I also attached the simulation file inside a 7z file
  The version of Lumerical is 2021 R2.5, version 8.26.2885
- March 21, 2022 at 10:19 pm
  
  Guilin Sun
  Ansys Employee
  
  First please check the source wavelength range and see if they agree. Occasionally this may happen for certain machines. But as long as the fitting is correct, it should not affect the result. If this happens again, please let us know your computer OS version.
  BTW: we are not allowed to download customer files in this forum. But my test did not show this issue:
- March 24, 2022 at 9:06 am
  
  amnonjw
  Subscriber
  
  Hi I see that you're using version 2022 R1.1. Can it be that there was a bug fix sometime between 2021-R2.5 and 2022-R1.1?
  I went over the release notes and didn't find anything about changes to the material fitting.
  
  This is the global source wavelength range (the simulation I uploaded doesn't override the global settings)
- March 24, 2022 at 3:34 pm
  
  Guilin Sun
  Ansys Employee
  
  There is no such bug report so even if there is a fix it is not intended. Please try the newest version. Actually I tested other versions when some customers reported this before.