Nanowire on waveguide coupling


My structure is a vertical nanowire photodetector on top of a SOI waveguide (see screenshot). I am currently working on the coupling between the waveguide and the nanowire.I already know all the modes allowed in both structures. I am trying to use the overlap function to match the polarization in both structures (by changing the geometry), but since this is non directional coupling i don’t know how to use the overlap function. do you guys have any idea how to proceed?

Thanks in advance


Dear @haweckerJG

Thank you for detailed explanation and providing supporting documents.

You are right, since these two structures are not in the same plane, overlap calculations will not work.

What is the nature of coupling here? some sort of scattering or evanescent coupling?
Do you have any thoughts on how we can calculate coupling from horizontal fiber to vertical one, or 90 degree sharp bend, assuming that they are identical?

Overall, I think FDTD will be the most intuitive tool to use and it will take into account mode overlapping, loss, and polarization. This is similar to grating coupler application example where the light of fiber is coupled to grating structures.

Please keep me updated with your thoughts and I will be happy to be of a help.


Thank you for your answer, I didn’t mentioned it, but the waveguide is made of Si, and the nanowire of InGaAs they are not identical. The coupling is evanescent.

In most simulations examples I saw, they used ports and mode expansions. I will thus explore this direction. I’ll keep you posted
Have a nice week end