The effect of resonant mode-coupling in high-finesse Fabry-Perot cavities

It is generally assumed that frequency and time measurements are related via Fourier transformation. This statement seems strictly valid but needs more consideration for a system as complex as a multi-mode optical resonator. This is shown in the paper for the cavity finesse F, which is a measure for the resolving power of an optical resonator. This finesse can be determined experimentally in either the frequency domain, by using cw injection and measuring the transmission spectrum, or in the time domain, by using pulsed excitation and measuring the cavity ringdown time.