Theoretical Analysis Of Nd³⁺:YAB And Nd³⁺:GdCOB SFD Lasers Under Different Pumping Methods

In this paper, Nd3+SFD laser model is developed based on rate equation. The theoretical optimization of Nd3+:YAB and Nd3+:GdCOB lasers are performed by means of the model.Firstly, the development of laser is introduced. The properties of, laser, crystal and self-frequency-doubling(SFD) laser crystal are introduced, too. Secondly, some detailed descriptions about Nd3+:YAB and Nd3+:GdCOB are given. Thirdly, the mechanism of direct and indirect pumping isdiscussed. On the assumptions that pump and laser beams are Gaussian beams, the laser models about four-level self-frequency-doubling laser systems are deduced.Base on the developed model, the effect of the direct and indirect pumping ways on the laser output is studied theoretically. The comparison between the theoretical results and the experiment results are made to confirm the validity of the model. As the calculated results show, for some Nd3+concentrations and crystal length, the SFD laser power of direct pump is lower than that of indirect pump, and it implies that direct pump is not suitable for all samples. The criterion determining which sample is suitable for direct pump is given. By the similar process, the criterions for the different SFD crystals and experimental parameters could be derived.For Nd3+:YAB, when Nd3+concentration and the crystal length meets XL>27.5m·at.%, where X is atomic percentage concentration, the SFD laser power of direct pumping is higher than that of indirect pumping. For Nd3+:GdCOB formula is XL>22mm·at.%.