Learning Forum

[iiskanda]

Dear community,

I'm trying to simulate cascaded interfaces through "Optical N port S-parameter elements". Both complex S11 and S21 are not constant. When S11 has low values the spectrum I get through an ONA has some dips, what I observe is that when S11 gets high values those dips get a weird S-shape, see attached. Why is this happening?

Regards,

Ilias

[iiskanda]

Following up on my previous post, I'd like to mention that I connect the S-parameter elements with straight waveguides and attenuators as in the image attached. Is there any case that I connect wavelength-dependent elements (S-parameter) with non-wavelength-dependent (straight waveguide + attenuators) that causes the problem?
Regards Ilias

[Odebowale]

Hello iiskanda Sorry I am currently a similar problem, I don't know if you have got solution to the posted question.
For my case, I am working on layered design ( consisting of 4 layers), so I extracted S matrix for each of the layer in FDTD then imported it interconnect. So, I have four different files each loaded to a separate "Optical N port S-Parameter" in interconnect. When I connected them connected using wire, the output transmission is not the same as the one I got when I extracted the S-matrix for the whole structure (without going through the layers one by one ). Is here something I am not getting right? Attached are copies of the two procedures: layer by layer extraction and extracting it for the whole design once.
In addition to the above question, is there away I can I visualize reflection/ plot from interconnect just like I did for transmission?
Thanks

[GWANG]

Hi iiskanda and Odebowale
Thank you for the post. Could you please let me know what are you plotting from the ONA for the two curves (blue and green)? Are they the real part of the transmission or the power transmission?

[iiskanda]

Hi Gwang This is the 20log10(abs(S21)) value for both curves. That's why I mention IL on the y-axis.