Growth, spectroscopic properties and laser performance of Nd3+-doped potassium ytterbium tungstate laser crystal

The 5 at.% Nd3+-doped potassium ytterbium tungstate (Nd3+:KYb(WO4)2, hereafter Nd:KYbW) laser crystal with the dimension up to 28 mm × 15 mm × 12 mm was grown by the top seeded solution growth (TSSG) method. The infrared spectrum of crystal sample was measured, and the vibrational peaks were assigned. According to the absorption and emission spectra of crystal sample, the absorption and emission cross-sections are 16.03 × 10−20 cm2 at 808 nm and 10.72 × 10−20 cm2 at 1067 nm, respectively. The fluorescence life of 4F3/2 energy level is 196.33 μs, and the fluorescence branching ratio for the 4F3/2–4I11/2 transition at 1067 nm is 55.74%. The energy transfer between Nd3+ and Yb3+ ions was observed from the fluorescence spectra pumped by 808 and 980 nm LD sources and the Stark levels of Yb3+ in Nd:KYbW crystal were determined. Highly efficient laser output up to 305 mW of Nd:KYbW crystal at 1067 nm has been achieved under pumping by a CW 808 nm laser diode at room temperature. The optical–optical conversion efficiency is 33.9% and the slope efficiency is 46.8%.