Laser performance of a 966  nm LD side-pumped Er,Pr:GYSGG laser crystal operated at 279  μm

We demonstrate a 966 nm laser diode (LD) side-pumped Er,Pr:GYSGG laser crystal operated at 2.79 μm under a high repetition rate. The lifetimes of the upper level I_11/24 and lower level I_13/24 are 0.66 and 0.85 ms, respectively. The laser performance under different repetition rates and pulse widths is experimentally studied with the optimal cavity structure. A maximum output power of 8.86 W is achieved at 125 Hz and 200 μs pulse widths, corresponding to the slope efficiency of 14.8% and electrical-to-optical efficiency of 7.7%. With increasing frequency from 50 to 200 Hz, the slope efficiency varies from 24.7% to 11.7% operated at a 125 μs pulse width. Moreover, the Mx2/My2 factors of 7.52/7.59 and Θ_x/Θ_y far-field divergences of 16.1/16.5 mrad are also measured. The results indicate that a high-performance 2.79 μm laser could be realized on the Er,Pr:GYSGG radiation resistant crystal by deactivation and LD side-pumping.