Growth, properties and Raman shift laser in tungstate crystals

Tungstate crystals including potassium rare earth metal double tungstates KRE(WO4)2 and barium tungstate BaWO4 are reliable and efficient Raman active crystals. In this paper, we report on the growth, physical properties and laser performance of these crystals. The pump threshold of Nd: KLu(WO4)2 pumped by a laser diode (LD) is 24 mW, and up to 188.3 mW of cw output at 1.073 μm is obtained with 746 mW pump power. The optical conversion efficiency is 25.3%, and the slope efficiency of the laser is 26.1%. The cw output for Yb:KLu(WO4)2 at 1.03 μm is 3.4 W pumped by an LD. Below 0.25 mJ pump energy, we obtained 0.07 mJ Raman laser output in the yellow (the first Stokes line at 559.7 nm) and the orange (the second Stokes line at 590.3 nm) with a 30-mm-long c-axis-oriented BaWO4 crystal. The conversion efficiency of the Raman laser is about 28%.