Methods of determining the frequency of a laser during its transient evolution such as during the switch-on of a laser are considered. This study is motivated by several illustrations of steady state laser systems which change their operating frequencies as their parameters are varied adiabatically. For evolving systems one would like an instantaneous measure of the frequency but for stochastic processes it is not possible. We discuss several different ways of characterizing the evolution of characteristic frequencies and phase fluctuations during transients that come as close as possible to instantaneous measures and which give evidence of the evolution that is taking place.
Neal Broadus Abraham,
"Characterizing frequency chirps and phase fluctuations during noisy laser transients", Proc. SPIE 1376, Laser Noise, (1 March 1991); doi: 10.1117/12.48069; https://doi.org/10.1117/12.48069