Q-switch regime of 3-μm erbium lasers

A mathematical model, based exclusively on spectroscopic data concerning radiative, non-radiative, and energy transfer processes, is proposed and used to simulate the Q-switch regime of three-micron Er: YAG laser. The connection between the main energy transfer mechanisms that make possible generation on the self-saturated transition I-4(11/2) --> I-4(13/2) (up-conversion from I-4(13/2), and I-4(11/2), cross-relaxation from S-4(3/2)) and the giant pulse characteristics is discussed. The radiative as well as non-radiative losses during optical pumping and giant pulse generation are defined and evaluated. A particular attention is given to FTIR Q-switch which demonstrated real qualities for 3-mu m Erbium lasers. The reasons responsible for experimental performances of Q-switched Er: YAG lasers inferior to those predicted by the mathematical modelling are analysed.