Diode-pumped ytterbium-doped Sr/sub 5/(PO/sub 4/)/sub 3/F laser performance

The performance of the first diode-pumped Yb/sup 3+/-doped Sr/sub 5/(PO/sub 4/)/sub 3/F (Yb:S-FAP) solid-state laser is discussed. An InGaAs diode array has been fabricated that has suitable specifications for pumping a 3/spl times/3/spl times/30 mm Yb:S-FAP rod. The saturation fluence for diode pumping was deduced to be 5.5 J/cm/sup 2/ for the particular 2.8 kW peak power diode array utilized in our studies. This is 2.5/spl times/ higher than the intrinsic 2.2 J/cm/sup 2/ saturation fluence as is attributed to the 6.5 nm bandwidth of our diode pump array. The small signal gain is consistent with the previously measured emission cross section of 6.0/spl times/10/sup -20/ cm/sup 2/, obtained from a narrowband-laser pumped gain experiment. Up to 1.7 J/cm/sup 3/ of stored energy density was achieved in a 6/spl times/6/spl times/44 mm Yb:S-FAP amplifier rod. In a free running configuration, diode-pumped slope efficiencies up to 43% (laser output energy/absorbed pump energy) were observed with output energies up to /spl sim/0.5 J per 1 ms pulse. When the rod was mounted in a copper block for cooling, 13 W of average power was produced with power supply limited operation at 70 Hz with 500 /spl mu/s pulses.