Abstract
Growth of the output power of an optically-pumped CH3OH FIR laser has been observed by an intracavity Stark-switching technique and discussed by a two-level model. The output power shows a relaxation oscillation similar to the one observed previously on many solid state lasers. The curves of growth calculated using a rate equation approximation fail to fit the observations, when the buildup time of the output power becomes comparable to or shorter than the relaxation time of polarization of the lasing medium. In that case, Maxwell-Bloch type equations, which give more precise description of the model than the rate equation, yield curves of growth in better agreement with the observations.
