Influence of Cr3+ concentration on the spectroscopy and laser performance of Cr,Er:YSGG crystal

Cr,Er:YSGG (Y3Sc2Ga3O12) crystals with 30 at. % Er3+ and two different concentrations of Cr3+ ions were grown by the Czochralski method. The spectra show the absorption coefficients at 450 and 654 nm and the fluorescence intensity at 2794 nm for 3 at. % Cr,Er:YSGG which are larger than those of 2 at. % Cr,Er:YSGG. A maximum pulse energy 1151.0 mJ operated at 5 Hz and 2.79 μm is obtained on the 3 at. % Cr,Er:YSGG crystal, corresponding to electrical-to-optical efficiency of 1.40%, slope efficiency of 1.71%, and threshold of 8.6 J. Under the same conditions, the values are 1029.8 mJ, 1.23%, 1.50%, and 12.6 J for 2 at. % Cr,Er:YSGG, respectively. Therefore, the 3 at. % Cr,Er:YSGG exhibits a larger output energy, higher laser efficiency, and lower pumping threshold. These results suggest that the laser performance of the Cr,Er:YSGG crystal can be improved by further optimizing the doping ions concentration and pumping parameters.