Efficient pumping scheme for neodymium-doped materials by direct excitation of the upper lasing level

TLDR

The direct upper‑laser‑level pumping of Nd:YAG R2 (869 nm) and Nd:YVO4 (880 nm) was compared with conventional ∼808‑nm band excitation, using a tunable cw Ti:sapphire laser as the pump source. The scheme raised the Nd:YAG oscillator slope efficiency by 10 % and lowered its threshold by 11 %, and increased the Nd:YVO4 slope efficiency by 5 % while reducing its threshold by 11 %, confirming theory and showing that laser‑material thermal loading can be substantially reduced.

Abstract

An efficient pumping scheme that involves direct excitation of the upper lasing level of the Nd3+ ion is demonstrated experimentally. The results obtained for direct upper laser level pumping of Nd:YAG R2 (869 nm) and Nd:YVO4 (880 nm) were compared with traditional ∼808-nm pump band excitation. A tunable cw Ti:sapphire laser was used as the pump source. In Nd:YAG, the oscillator slope efficiency increased by 10% and the threshold decreased by 11%. In Nd:YVO4, the slope efficiency increased by 5% and the threshold decreased by 11%. These results agree with theory. The increase in optical efficiency indicates that laser material thermal loading can be substantially reduced.