Frequency data to temporal data


#1

Hello,

I am trying to extract the charge density as a function of time. The divergence current analysis group
calculates the spectrum of the charge density - it uses the E(w) in the script, calculated
by the frequency-domain monitor.

Therefore, I try to do the inverse transform in matlab, but I am facing a problem:
The frequencies I chose to simulate are in the visible range (3.75-7.5e14 rad/s) and the resulting spectrum
is in that range. So if I use ifft function should I get the physical signal as a function of time, or should I include lower frequencies in my simulation as well? Does Lumerical simulate in all frequencies and provide me only the frequencies I asked for?


#2

Hi @nadavfain

You can perform fft and invfft in our scripting language. Your concern is correct and if you have spectrum only at a certain bandwidth, you will loose part of your signal in time domain. While using a very broadband simulation may work, you could obtain field profile as a function of time using time monitors:
https://kb.lumerical.com/en/index.html?ref_sim_obj_monitors_time.html

Hope this was helpful.