Photonics

Photonics

Dipole Power discrepancies when applying symmetry BC’s FDTD

    • Mike Neville
      Subscriber

      I am using an FDTD simulation  to model the transmission features of a SOI patterned structure. I am using a dipole source to model this transmission (along X axis), but have observed a difference in the measured dipole power when applying anti-symmetric boundary conditions to the X min axis and symmetric boundary to the Y min axis of the FDTD region, and when running the simulation without any boundary conditions (PML on all axes). It is my understanding that the use of these conditions should allow me to reduce the running time of the simulation, whilst exactly replicating the results of a simulation without these conditions. The structure I am simulating demonstrates rotational symmetry about the z-axis, but I have noticed that this discrepancy is present even when simulating the dipole source within a homogeneous material. Is anybody able to help me further with this? Why is this discrepancy present?

       

    • Guilin Sun
      Ansys Employee

      THe main cause is the mesh I believe. Please force the simulation mesh to be symmetric along x and y:

      When using symmetry BCs it automatically forces the dipole to be shifted compared to the original meshing.

    • Mike Neville
      Subscriber

      Looks like that has sorted it! Thank you!

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