Modeling pulse shape of Q-switched lasers

摘要

A general approach describing the pulse shape and temporal widthnof Q-switched lasers has been derived. Based on a normalizednintermediate variable describing the ratio of population inversionndensity at the beginning of Q-switch to that at threshold, a generalizedncharacteristic equation that governs passively and actively Q-switchednlasers is derived. From the characteristic equation, the pulse symmetrynproperty and pulse width can be described and easily calculated for anyngiven operating parameters, and the waveform of the laser pulse can benreconstructed without solving the laser rate equations. An approach isnalso given for the case of intracavity frequency-doubled Q-switchednlasers. Theoretical results show agreement with experiments for a diodenpumped Nd:YAG laser system that is passively Q-switched by a Cr4+n:YAG absorber