Optical and laser characterization of 2% Nd:YAG ceramics elements

Abstract

We report on the first, promising production of Nd:YAG ceramics made in Poland. The Nd:YAG ceramics was produced by a solid-state reaction of high-purity (4N) nanometric oxides powders i.e. Al₂O₃, Y₂O₃ and Nd₂O₃. After sintering process mean grain sizes of 2%Nd:YAG samples were about 20 μm and transparency of its were comparable to 0.9% Nd:YAG single crystal. Two types of active elements: rods and slabs were fabricated and characterized in several diode pumping schemes. In end pumping configuration as a pump source 20-W fiber coupled laser diode operating in low duty cycle regime (1 ms pump duration /20 Hz) was deployed. In the best case, 3.7 W of output power for 18 W of absorbed pump power, M² <1.4 were demonstrated for uncoated ceramics Nd:YAG rod of φ4x3mm size in preliminary experiments. For the ceramics of two times lower Nd dopant level above 30% slope efficiency was achieved. In case of slab ceramic side pumped by 600-W laser diode stack above 12 W was demonstrated with slope efficiency of 3.5%.