Reply To: Lumerical help, dielectric slab waveguide

[Amrita Pati]

Hi Marton, 

Thanks for sharing additional information! Starting with the thickness of the core sounds like a good plan to me. The easiest approach to start with here would be to just have one structure, which will be the core. Then you can have a large simulation region to make sure that it would cover the core and still have a few um from the boundaries. For example, let's say for the highest value of thickess the core extends from -2.5 um to 2.5 um. You can make the FDE region to extend from -5 um to 5 um to begin with. I will also ask you to use a mesh override region over the core to make sure that it is properly resolved. 

You can define the mesh override based on the core, so that even if the core dimensions change in the sweep, the mesh will always cover the core. For example, in the screenshot shown below the structure "WG" is my core:

For the cladding, I would recommend you not to add any geometry but to just use it's index as the background index of the simulation region. This way you won't have to worry about the layers overlapping with each other. 

For this, you can go to the General Tab of the solver, and change background material to the cladding index as shown below:

Now you won't have to adjust any other thicknesses if you vary the core thickness in the sweep. Because the background index get the lowest priority among all the structures. But what you will effectively have is a core-cladding region, the cladding being the entire background. 

But if the cladding has a finite thickness on both sides then we will have to rely on scripting, we are not allowed to share files on this platform, so I won't be able to share an entire simulation file, but I can copy and a paste some script. Let me find the script and share here.

Regards,
Amrita