Topics related to Lumerical and more

FDE mode overlap analysis


    • Nivedita Vishnukumar

      I have been trying to find the overlap from mode that is simulated in FDE and a mode previously simulated and saved in .ldf file. The mesh, fde size and region are same for both simulations. I manually loaded the ldf file. With reference to figure attached below, I tried to find overlap with a gaussian beam created by the software (dcard-1,2), "Calculate overlap" works and gives a value. But for ldf file that I loaded (dcard 3,4,5..), "Calculate overlap" does not work at all. I am confused why the problem arises. Also if there is a way to access global data from .ldf through scripting, please let me know ( It always gives the error, "in getdata, no data structures named global_mode2 were found" )For finding mode overlap with an external ldf file

    • Amrita Pati
      Ansys Employee

      Hi Nivedita,

      I apologize for the late reply. You mentioned that the FDE size in both the cases is same, which is required for the calculation of the overlap integral. But the wavelength has to be same as well. Were the modes calculated at the same wavelength in the first FDE simulation?

      To see a list of all availabe dcards, you can use the following script command:


      For example, in one of my simulations it returns the following result as I have just one mode in the global deck: 

      Then you can also use the following command to see what properties of the mode in the global deck are available to you:


      In my case, this returns the following result:

      Now you can use the following script command to access any of above properties (effective index shown below): 

       index_g1 = getdata("::global_mode1","neff");

      Please let me know if you have any further questions.


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