Discrepancy between set and injected wavelength of plane wave source.

lStolzlStolz Member Posts: 3

Hi,

I have major problem with the accuracy of the injected (single) wavelength of a plane wave source. As seen below, I set the wavelength of my source to 0.71um. However if I measure the electric fields in the simulation, they show that a wavelength of approx. 0.9um was injected. Is this a known problem with a workaround?

Thanks in advance!

Cheers

Levin



Answers

  • gsungsun Posts: 1,102Ansys Employee

    Hi, This is not a problem and actually it is the advantage of FDTD: single simulation can give broadband result. This is because, FDTD is a time domain method, which injects pulsed signal as shown at the bottom of the first screenshot. Even though you set a single wavelength, which just informs the frequency-domain monitor that by default it only records the result of that specific wavelength. If you modified the default settings of the monitor to not use the source specified-wavelength range, it will record whatever the wavelength you set in the monitor. In other words, FDTD actually has broadband data available. It is your monitor that picks up the frequency-domain result whatever the monitor is set to get. Please check your monitor settings:


    the above is the default setting, which will only gives you result at 0.71um, even though the frequency points are 5.


    below is modified case for illustration purpose: to record 5 frequency points from 0.4~1.0um:


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