Study On Thermal Effects Of End-pumped DPL

The paper deals with Thermal effect in the crystal of diode pumped solid-state laser.Firstly, one of the simplest models, which is called ideal Thermal-lens, is applied todiscuss the transformation process from stable resonator to unstable resonator caused byThermal effect. This transformation is presented mainly by steep rise of loss in resonator.This changing process of loss is not only related to the changing of pumping power, butalso to the size of Laser Crystals.In order to analysis the influence of Thermal effect accurately, the actualmanifestation of Thermal effect is further studied in this paper. The states ofTemperature distribution in different kind of pumping lights are calculated in finiteelement method. And on this basis, the manifestation of Non-ideal Thermal-lens ingeneral conditions is given and illustrated. Compared with the model of idealThermal-lens, the differences between the actual Thermal effect and ideal Thermaleffect are presented. In order to quantitatively express the negative effects of non-idealThermal-lens on the Gaussian beam through it, the paper specially introduces aparameter, called Thermal effect factors, which can reflect the impacts on differentmodes of Gaussian beam.One of the main influence factors of Thermal effect on laser is the increased loss inresonator. In the final part of this paper, we study the method for estimating the laserloss caused by heat in general Thermal effect. And when laser is running in thefundamental-mode and every lower-level-mode, the changing law of one-way losscaused by heat in resonator is calculated.Research finds that thermal-effects-factor becomes increasing with the increases ofpump power. When pump radius increases from 0 to about 0.55mm,thermal-effects-factor increases sharply, then decreases slowly. One-way loss inresonator becomes increasing with the increases of pump power, becomes decreasingwith the increases of pump radius.