Thermal focal length and optimal pumping position of Nd: NaY(WO_4)_2 crystal

Thermal focal length of fiber-coupling LD end-pumped Nd:NYW laser were measured within the range of pump power from 3.5 to 6.5 W with a method of nonstable cavity, and the results were compared with the theoretical results. Meanwhile, the optimal pump position was investigated under different pump powers. The experimental results are consistent with theoretical prediction and the phenomena are interpreted reasonably.