Incorrect index values in Mode or Port sources

- July 30, 2021 at 3:33 am
  
  xiaolei
  Subscriber
  
  Hello,
  For a mode or port source, when I click the "Visualize Data" to check the selected mode and index profile, I find the index values are incorrect. For example in the grating coupler example (https://support.lumerical.com/hc/en-us/articles/360042305334-Grating-coupler). In the 'grating_coupler_2D.fsp' file, if we visualize the selected mode of port 2, we can get the index and mode profile as shown in the following figure. The index value of waveguide core (Silicon ) is ~6 here, which is abvously incorrect. The right index value is around ~3-4. Can you explain why this happens or whether my understanding is wrong? Looking forward to your reply. Thank you.
- July 30, 2021 at 3:43 pm
  
  Kyle
  Ansys Employee
  
  The index is saved as a vector (nx, ny, nz), in case the index is anisotropic. Here you're viewing the magnitude of this vector, which is sqrt(nx^2 + ny^2 + nz^2) = sqrt(3)*n. You can change the "Vector operation" to X, Y or Z in the Attributes section to view the individual components of the index.