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

The performance of the first diode-pumped Yb(3 )-doped Sr (5)(PO(4))(3)F (Yb:S-FAP) solid-state laser is discussed. An InGaAs diode array has been fabricated that has suitable specifications for pumping a 3x3x30 mm Yb:S-FAP rod. The saturation fluence for diode pumping was deduced to be 5.5 J/cm (2) for the particular 2.8 kW peak power diode array utilized in our studies. This is 2.5x higher than the intrinsic 2.2 J/cm (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 6.0x10(-20) cm(2), obtained from a narrowband-laser pumped gain experiment. Up to 1.7 J/cm(3) of stored energy density was achieved in a 6x6x44 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 ~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 mus pulses