Learning Forum

[Weixiao Xu]

Hello,

I am using Lumrical MODE's varFDTD simulation to model a microring resonator, and I would like to know if it is possible to set up multiple layers of materials with different refractive indices in the y-direction, as shown in the schematic diagram. If this is possible, could you please tell me where the green marker in varFDTD should be placed? If not, does this mean that I can only simulate such a model using the 3D FDTD feature within Lumrical FDTD?

Thanks！

[Guilin Sun]

1st, layered structure in z works fine, as long as the mode is well supported.

when there are two mateirals in xy plane, if the difference of the refractive index is not ver different , it would work. If the difference is large, as what you concerned, it would be hard to say which material the reference green point should be. VarFDTD works as to decopose the 2D mode into one vertical/slab mode and the other in plane, both are 1D. When the combination of the two 1D modes can well represent the 2D mode, the result can be accurate. Otherwise there will be some comprises for result accuracy.  You may need try the two, and compare if the results are significantly different. If so you will need to use 3D FDTD. Even though the results are close with each other, it is also recommended to use 3D FDTD for verification.