I have an SOI ring resonator and I need to find the quality factor of this resonator if the coupling losses due to the access waveguide weren’t considered. In other words, I need the unloaded or intrinsic quality factor of the resonator. How can I do this using FDTD simulation (not using theoretical calculations)?
When you refer to the intrinsic Q of a ring, I assume you are just interested in the ring only. If this is the case, it sounds like our whispering gallery example (https://kb.lumerical.com/en/index.html?diffractive_optics_cavity_whispering_gallery_modes.html). You could excite the mode by placing some random dipoles like the example. You will also need the Q analysis group to find the Q (https://kb.lumerical.com/en/index.html?diffractive_optics_cavity_q_calculation.html).
Will this solve your problem?
What about loaded Q? Should we just get it from transmission plot of a ring?
I believe this page may be of your interest if you would like a example for reference?