Performances of a diode end-pumped GYSGG/Er,Pr:GYSGG composite laser crystal operated at 2.79 µm.

We demonstrate a comparative investigation on Er,Pr:GYSGG and GYSGG/Er,Pr:GYSGG composite crystals at 2.79 µm. Simulating results show the highest temperatures are 369 K and 318 K, respectively. A maximum output power of 825 mW with slope efficiency of 19.2% and maximum laser energy of 3.65 mJ with slope efficiency of 22.7% are obtained in the GYSGG/Er,Pr:GYSGG composite crystal, which have an obvious improvement than those of Er,Pr:GYSGG crystal. The thermal focal lengths are respectively 41 and 62 mm when the pump power is 2.5 W. All these results indicate that the GYSGG/Er,Pr:GYSGG composite crystal has great advantages in reducing the influence of thermal effects and improving laser performances.

Spectroscopic properties and diode end-pumped 2.79 µm laser performance of Er,Pr:GYSGG crystal.

We demonstrate a 968 nm diode end-pumped Er,Pr:GYSGG (Gd1.17Y1.83Sc2Ga3O12) laser at 2.79 µm operated in the pulse and continuous-wave (CW) modes. The lifetimes for the upper laser level 4I11/ 2 and lower level 4I13/2 are 0.52 and 0.60 ms, respectively. The laser produces 284 mW of power in the CW mode, corresponding to the optical-to-optical efficiency of 14.8% and slope efficiency of 17.4%. The maximum laser energy achieved is 2.4 mJ at a repetition rate of 50 Hz and pulse duration of 0.5 ms, corresponding to a peak power of 4.8 W and slope efficiency of 18.3%. These results suggest that doping deactivator Pr3+ ions can effectively decrease the lower-level lifetime and improve the laser efficiency.

Spectroscopic, diode-pumped laser properties and gamma irradiation effect on Yb, Er, Ho:GYSGG crystals.

We demonstrate a diode end-pumped Yb, Er, Ho:Gd(1.17)Y(1.83)Sc(2)Ga(3)O(12) (GYSGG) laser operated at 2.79 µm in continuous-wave mode. Spectral analysis shows that Yb(3+) and Ho(3+) act as sensitizer and deactivator ions, respectively. Pumping with a 967 nm laser diode produces the maximum output power of 411 mW, corresponding to optical-optical conversion and slope efficiencies of 11.6% and 13.1%, respectively. The minimum laser threshold is only 81 mW because of Ho(3+) doping. The laser properties are only slightly influenced by 100 mrad gamma irradiation. The Yb, Er, Ho:GYSGG crystal possesses excellent radiation resistance and is a potential laser gain medium in radiant environments.

[Crystal growth and spectral parameter computation of Yb:YAG].

In this article, a good-quality crystal Yb:YAG was grown by pull method, and its absorption spectrum of 200-3000 nm was measured at room temperature. Its absorption of 200-300 nm is from the host YAG, and there exists only the characteristic absorption of Yb3+ in the range of 390-3000 nm. Judd-Ofelt theory computation indicates that the absorption and emission oscillator strengths of electric dipole of (24 at%) Yb:YAG are 3.58 x 10(-6) and 4.77 x 10(-6), respectively, and the absorption and emission transition probabilities are 879 and 1171/s respectively. As for magnetic dipole, the absorption and emission oscillator strengths are 3.32 x 10(-7) and 4.43 x 10(-7) respectively, and the absorption and emission transition probabilities are 82 and 109/s respectively. The lifetime of the energy level2 F(5/2) is 781 micros.