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[sme8]

Hey,

I use an embedded high-Q analyzer in the FDTD module. Essentially, I use ring-down to estimate the quality factor of ultra-high Q factors. However, I realized that the Q factor it calculates is highly dependent on the source settings. For example, I set all the parameters the same for two simulations and only modified the wavelength of the source. I found that if I set my source wavelength to 700-900 nm, the quality factor is different from another simulation with a wavelength of 740-760 nm. Assume my desired resonance occurs at 750 nm. Please be informed that and the resonant wavelength does not change with different source wavelengths. I use an auto non-uniform mesh for my simulations.

I also modified the time domain properties of my source to have a very narrow band signal in the frequency domain (consequently wide in the time domain) near my resonant wavelength, and again, the Q factor changed dramatically.

What do you think? Which one is more accurate?

Thank you for your support and help.

[Guilin Sun]

This post is replied here Q factor calculation