Abstract The absorption spectra of Tb,Tm:YVO$_4$ and Ho,Tm:YVO$_4$ are measured. The radiant and non-radiant transition probabilities from higher level to lower level, $A_{i,j}$ and $\omega_{i,j}$, and the cross-elaxation probability are calculated in virtue of Judd－Ofelt and Dexter theories. The fluorescence lifetime of Tm$^{3+}$ in the Tb$^{3+}$ (or Ho$^{3+}$) co-doped crystal is calculated. It indicates that the lifetime of initial level $^3$H$_4$ of the laser transition can be shorter than that of terminal level $^3$F$_4$ of the transition if the atomic percentage of Tb$^{3+}$ (or Ho$^{3+}$) ions is bigger than about 1 at%: namely, by means of the co-doping Tb$^{3+}$ (or Ho$^{3+}$) ions the self-termination phenomenon of laser light can be eliminated. Inserting the optic parameters to the formula deduced here on the laser threshold power $P^{(4)}_{\rm th}$ and the slope efficiency $\eta^{(4)}_{\rm s}$ of the four-energy-level system, we obtain the relationship of threshold power $P^{(4)}_{\rm th}$ to the concentration of Tm$^{3+}$ ions and discuss the effect of Tb$^{3+}$ (or Ho$^{3+}$) ion concentration on the laser threshold power $P^{(4)}_{\rm th}$ around 1.5μm wavelength. The result shows that Tb,Tm:YVO$_4$ crystal is a better choice to make the laser at $\sim1.5$μm wavelength than Ho,Tm:YVO$_4$ crystal. We give the appropriate composition of (1－2) at% Tb, (1－2) at% Tm:YVO$_4$, just for reference.
Received: 14 March 2003
Revised: 23 April 2003
Accepted manuscript online:
PACS:
42.60.Jf
(Beam characteristics: profile, intensity, and power; spatial pattern formation)
Fund: Project supported by the Foundation of the Natural Science of Zhejiang Province, China(Grant No 600087), and by the State Key Laboratory of LMOI-013 Zhejiang University, China.
Cite this article:
Huang Li-Lei (黄莉蕾), Fu Yan-Bin (付晏彬), Wu Liang-Neng (邬良能) Analysis of the laser performance of Tm3+, Tb3+(Ho3+):YVO4 crystals at ～1.5μm wavelength 2003 Chinese Physics 12 1417
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