LD双端抽运YVO_4-Nd:YVO_4-YVO_4复合晶体的高功率调Q基模固体激光器研究

Investigation on LD Double-End-Pumped High Power Q-Switched YVO_4-Nd:YVO_4-YVO_4 Fundamental Mode Solid State Laser

使用高功率激光二极管(LD)双端抽运复合晶体结构是获得高功率高效率基模输出激光器的有效手段。使用YVO4-Nd:YVO4-YVO4复合晶体作为激光增益介质,并采用平-平非对称腔结构,使激光器运行于动态稳定区,在抽运功率为70 W时,连续基模输出功率可达34 W,光-光转换效率为48.6%;但在调Q状态下,脉宽较长,达80 ns左右,某些时候不能满足激光器的后续应用。在缩短谐振腔长臂之后,当抽运功率为66 W时,获得了连续30 W的基模激光输出,光-光转换效率为45.5%;在调Q状态下获得了脉冲重复频率在10～200 kHz的准连续输出,并对平均输出功率、脉冲宽度和峰值功率随脉冲重复频率的变化进行了详细的实验研究。在重复频率为10 kHz时,得到平均功率19.3 W,脉宽28 ns的基模输出,对应于单脉冲峰值功率为68.9 kW;在重复频率为100～200 kHz时,平均输出功率始终保持在27 W左右,脉冲宽度在50 ns左右。对谐振腔设计及实验现象做出了合理的分析,指出了进一步改进激光器设计从而获得更短脉冲宽度的方向。

It is an effective method to achieve high power,high efficiency fundamental mode laser output that adopting laser diodes double-end-pumped composite crystal configuration.By employing YVO4-Nd：YVO4-YVO4 composite crystal as gain medium and introducing unsymmetrical plane-plane resonator configuration for achieving effective fundamental mode operation,we obtain 34 W CW fundamental mode output power with a pump power of 70 W and an optical-optical conversion efficiency of 48.6%.The laser pulse width reaches 80 ns in acousto optically（AO） Q-switched mode operation,which might be too long for later applications.After shortening the longer arm of resonator,we obtain 30 W CW fundamental mode output power with a pump power of 66 W and an optical-optical conversion efficiency of 45.5%.In the Q-switched mode operation,quasi-CW output with pulse repetition rate from 10 to 200 kHz can be obtained.The relationships of the average power,the pulse width and the peak power versus the pulse repetition rate are investigated in detail.With the pulse repetition rate of 10 kHz,we obtain an average power of 19.3 W with a pulse width of 28 ns,corresponding to a peak power of 68.9 kW.With pulse repetition rate between 100 and 200 kHz,the average power holds at about 27 W and pulse width about 50 ns.Additionally,the analysis on the resonator design and experiment results shows that further optimization for achieving much shorter pulse width and higher peak power is possible.