I can calculate fsr and fwhm manually by measuring width of peaks but that is not accurate data. how to get the accurate data for fwhm, q factor and extinction ratio for a transmission spectra of ring resonator in origin software?
What do you mean by "not accurate data"? If the fitting function you are using doesn't match your peak shape, reconsider if you are using the right function type (Gaussian, Lorentz, Voigt). Once you have done that, the quality factor is no longer a big deal since it's just the peak center frequency divided by FWHM.