Influence of neodymium concentration on the strength of thermal effects incontinuous-wave diode-pumped Nd : YVO4 lasers at 1064 nm

The influence of neodymium ion concentration on the continuous-wave power p erformance of diode-pumped Nd:YVO4 lasers was experimentally investigated b y using three crystals of approximately the same total absorption but diffe rent Nd concentrations of 0.5, 1, and 3 at.%. In situ measurements indicate that strong thermal lensing occurs in the highly doped sample (3 at.% Nd) and precludes scaling of the output power to large values. Results also sho w that undesirable thermal effects are dramatically reduced with decreasing active-ion concentration. The best power performance was obtained with a 1 0-mm-long Nd:YVO4 sample that had 0.5 at.% Nd. In this case, up to 6.5 W of continuous-wave output power was obtained at 1064 nm by using a 3% transmi tting output coupler.