Wavelength-domain analysis


#1

Hi,

I’m trying to simulate the transmission characteristics of a ring resonator. I’ve been able to get something using varFDTD, but I’m not certain that it shows what I am actually looking for. In the Source settings, I am able to input a spectrum, but it seems to be bound to a blackbody shape - is there a way to use a flat source profile so that I can see the effects of the resonator alone, without artifacts from the source? Basically, I want the transfer function itself, not the result of applying the transfer function to an input function.

Secondly: Time-domain results are not necessary for my work, but I understand if they are necessary for the software to find the wavelength-domain results. Should I continue using the varFDTD, or would FDE be better? The example file and online tutorials show how to get data using Monitors for FDTD, but I’m not certain how to visualize or even perform a wavelength-sweep in FDE.

Thanks for any help!


#2

By default, the frequency domain power and profile monitors in the varFDTD solver will return CW normalized results. This means that the results at each frequency point are normalized by the source power injected at that frequency, so you won’t see the effect of the shape of the spectrum of the injected source pulse. This is discussed in detail on this page:
https://kb.lumerical.com/en/index.html?ref_sim_obj_cw_normalization.html

This means that you should already be getting the transfer function result that you’re looking for without needing to inject a single frequency signal instead of the default source pulse.