Use of spectrum source

    • xluna

      Dear Tech Support Team,

      I have a normalized intensity profile vs wavelength from a light emitter LEC (Light emitting capacitor), I would like to use this spectrum for my results. I found this link:, where I can multiply the impulse response of the system by the new power spectrum. I understood for step 1, I need to run the simulation normally, and the result is the impulse response (T or Pab in my case). So,  is it correct to multiply my results directly with my normalized intensity spectrum? 

      For example, if a wavelength of 400 nm gave me a result of Pabs= 0.65 and the intensity of my spectrum for this wavelength is 0.2, can I multiply 0.65 x 0.2 = 0.13 to calculate the new Pabs when I used the spectrum? 


      I greatly appreciate your help in this regard.

      Thank you,


    • Guilin Sun
      Ansys Employee

      Sorry to reply you late due to some circumstances.

      Yo are right. In FDTD the simulated transmission or reflection is always normalized with the source spectrum, which is from the time-dependent signals. Once the result removes the source-dependency, you can multiply your source spectrum to get the absolute results.  However, since most deivces work linearly, please make sure it is reasoable to use absolute value, as many experiments also give normalized results.



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