Photonics

Photonics

what is the difference between the spectrum from time-monitor and DFT monitor

    • xihangshi
      Subscriber

      I run a simulation with a dipole (150THz-200THz) locates at the origin point, and a point time-monitor and a DFT monitor at (0,0,z=0.1mu m), the spectrum from the time-monitor (blue curves) and the DFT monitor (red curves) do not match, what is the reason?

      I find the spectrum from the time monitor is the Fourier transform of the temporal signal but without timing the time-step, but cannot understand what is the spectrum from the DFT monitor. 

       

       

       

       

    • Guilin Sun
      Ansys Employee

      You are right that "the spectrum from the time monitor is the Fourier transform of the temporal signal but without timing the time-step," you can multiply it if you want. Spectrum from a time monitor is just to provide un-normalized result, eg, not normalized with the source power.

      The spectrum from the DFT monitor is normalized with the source power. Please refer https://optics.ansys.com/hc/en-us/articles/360034394234-Understanding-frequency-domain-CW-normalization 

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