I am simulating an adiabatic coupler’s response to thermal tuning with varFDTD in MODE. And I have some problems here. Please see the attached for the simulation files.
varFDTD with thermal index perturbation
- Simulate the coupler in varFDTD without index perturbation and it works fine.
- Simulate the 3D temperature profile in DEIVCE and then import it to MODE. Create an index perturbation material with the base material to be Silicon. Works fine for FDE but not varFDTD. Light stopped propagating at the boundary of the thermal region if it is smaller than the FDTD simulation region
or at the source if the thermal region is larger than the FDTD simulation region
Inline image 1
It does not even work for the case where there is zero tuning.
Mode expansion monitor
The second problem is with the mode expansion monitor.
When I only placed one mode expansion monitor at mon_in0 and add all four field monitors to its monitoring list, the mode expansion monitor seems only work for mon_in0, but did not give a reasonable number for other ports, which has the same cross section with in0. Consequently, I have to place a mode expansion monitor at every port with a field monitor.
Attached is the script (for MODE) TestScript.lsf (4.3 KB)and temperature profile is available through the link.
They are not the actual structure but two simple parallel waveguides, but enough to show the problem. Run the script and then hit the button to run the simulation.