Learning Forum

[Davide Monopoli]

Hello everyone, I wanted to ask a support related to the need of inserting the correct values of effective index in a Lumerical interconnect model for a MZI.
Seems that in Interconnect you cannot launche a mode-source that takes into account the fundamental mode TE or TM supported by the waveguide.
So you can insert in the object "straight waveguide" the values called : effective index, group index and dispersion.

How I can put the correct ones in this object? It is "enough" to estimate them at a certain frequency ( because I cannot give more than one value in input) from FDE solver and then wrote it in the object?
I don't know if it is enough accurate..but I don't know other solutions..
Also it is not possible to set the cover and cladding index in Interconnet?


Thanks and I hope you can give me a feedback,
Davide

[Davide Monopoli]

just to be accurate, these are the values from FDE considering 300 nm SiN thickness as guided medium, cover air and cladding SiO2 1.44 at 1550 nm.
In theory my simulation should run from 1520 to 1620 nm

[Niki Papachristou]

Hi Davide,

Thank you for reaching out to us! I believe there are two ways to simulate your waveguide in Interconnect: You can import the values mannually as you are describing or you can use the Exptort for Interconnect option on FDE:

You can follow this Waveguide (FDE) example for the second case. I believe that you should be accuate as long as you have the correct valu for the disperssion. We have several articles on how to calculate and export the disperssion: Algorithm to calculate dispersion and effective index in mode solution, Dispersion analysis of SOI waveguide,Sweep analysis for dispersion calculations. I am not quite sure what you mean about the cover index, regarding the cladding index however, I believe that since you are designing a waveguide on FDE (or elsewhere) the effective refractive index is what you are looking for. You can also reffer here in case you are looking to simulate an optical fiber: Optical Fiber (FIBER) - INTERCONNECT Element.

Finally you can't import an Mode source but you can import a Mode waveguide into interconnect: MODE Waveguide (WGD) - INTERCONNECT Element,Create MODE Waveguide Element.

I hope that was helpful.

Kind Regards,

Niki

[Davide Monopoli]

 

Hi Niki, thanks a lot for the very important informations!
I have just a doubt about how to set the width of the mode waveguide, because in the properties it is intrinsically set just the length…you have any ideas about it?

For the neff and cover material you replied to all my doubts.

 

Thanks,
Davide

 

[Niki Papachristou]

Hi Davide, 

I believe you should change the width of your waveguide on the MODE simulation before you export the data to Interconnect. Since you have a specific mode for a specific width and this is what you are importing into Interconnect.

Kind Regards,

Niki