Efficiency enhancement and power scaling of Nd lasers

摘要

Based on the analysis of the partial efficiencies that characterize the various steps in the excitation flow inside the pumped Nd-activated laser materials, the paper discusses some possibilities to enhance the laser emission parameters and to reduce the generation of heat by non-radiative processes: the direct pumping into the emitting level, the use of concentrated Nd laser materials, the use of new Nd laser materials such as the Nd:YAG ceramics and the need for advanced laser resonator design. These approaches are demonstrated by the highly efficient laser emission in low inversion regime, such as continuous-wave emission in the 1- and 0.9-μm range for diluted and concentrated Nd:YAG single crystals and ceramics and in Nd:YVO_4 single crystals, repetitively Q-switched Nd:YAG lasers, frequency-doubled continuous-wave Nd:YAG lasers and self-frequency doubling in Nd:GdCa_4O(BO_3)_3.