Quantitative analysis of decay transients applied to a multimode pulsed cavity ringdown experiment

The intensity and noise proper-ties of decay transients obtained in a gener ic pulsed cavity ringdown experiment are analyzed experimentally and theore tically. A weighted nonlinear least-squares analysis of digitized decay tra nsients is shown that avoids baseline offset effects that induce systematic deviations in the estimation of decay rates. As follows from simulations n ot only is it a method that provides correct estimates for the values of th e fit parameters, but moreover it also yields a correct estimate of the pre cision of the fit parameters. It is shown experimentally that a properly al igned stable optical resonator can effectively yield monoexponential decays under multimode excitation. An on-line method has been developed, based on a statistical analysis of the noise properties of the decay transients, to align a stable resonator toward this monoexponential decay. (C) 2001 Optic al Society of America.