Hello, I am modelling a ring coupled to a bus waveguide however I'm just modeling half of the ring in order to get transmission through the ring. The power transmission should be my coupling coefficient squared. This works fine so far. I started in VarFDTD and then tried to confirm with full 3D fdtd, I am getting a lot stronger coupling in 3D fdtd which is the opposite trend than what I expected because I know that varFDTD tends to give shorter 100% coupling lengths. No loss in the Z direction in varfdtd.