FDTD simulation time vs Pulse duration in transient charge ?

- November 7, 2022 at 8:05 am
  
  Mariah Ha
  Subscriber
  
  Hello,
  In transient charge, I introduced a pulse of optical generation ( obtained from FDTD) in the transient parameters tab to study the impulse response. Should the pulse total duration ( pulse end - pulse start ) be equal to the simulation time of the FDTD simulation , or they are not necessarely the same? For example , if I choode to introduce a 1 picosecend optical generation pulse in charge, should I use a 1000fs long FDTD simulation ?
- November 7, 2022 at 5:53 pm
  
  Guilin Sun
  Ansys Employee
  
  They are not necessarely the same, since in most cases the FDTD simulaiton time is to get the frequency-domain result from the time signal through the Fourier transform, and as long as the Fourier transform is accurate the time can be short, whereas in CHARGE the simulation time is physical, eg, it has limited bandwidth so its response is not instant.
  - November 7, 2022 at 6:20 pm
    
    Mariah Ha
    Subscriber
    
    Thank you for the prompt reply. I mean when I have a 1 picosecond generation pulse in charge,do I need to set any parameter in FDTD to 1 picosecond .
- November 7, 2022 at 10:30 pm
  
  Guilin Sun
  Ansys Employee
  
  No, no need. CHARGE uses the steady-state result from FDTD.