研制一台激光二极管(LD)侧面抽运双棒串接准连续Nd∶YAG折叠腔高功率绿光激光器,理论分析了热致双折射效应对系统的影响,并对用石英旋转片补偿前后的情况进行模拟对比。在考虑了补偿后的情况下设计了热稳定谐振腔。实验中采用两个串接的由30个20 W的LD阵列侧面抽运的Nd∶YAG棒和Ⅱ类临界相位匹配HGTR-KTP晶体,在抽运电流均为21.6 A,重复频率为27.2 kHz时,获得了最大平均输出功率为164 W,脉冲宽度为130 ns的532 nm绿光输出,光-光转换效率为13.7%,测得光束质量因子为M2x=9.52, M2y=9.86,不稳定度为2.3％。实验结果显示,经补偿后的激光系统能在宽的稳区范围内稳定运转。

A stable and efficient all solid-state green laser with average power over 30 W is studied. The phase mismatching and thermal lens effect induced by local temperature rise of doubling frequency crystal are the major reasons affecting frequency doubling efficiency and laser output power stability. The method of grads-compensating temperature controll is used to adjust the operating temperature of frequency doubling crystal with large size. This temperature control system debases the inside and outside temperature grads of crystal to compensate the phase mismatching and thermal lens effect of frequency doubling crystal. This laser that is side-pumped by three bars laser diode array of 60 W and adopts the high efficiency flat-concave cavity, intracavity frequency doubling resonance structure, and acoust-optic Q-switching generates a maximum green average power of 31.6 W with 110 ns pulse width and 10 kHz repetition rate when pumped current of laser diode was 25 A and pumped power was 174.6 W. The optic-optic transition efficiency is up to 18.1%, and power stability is up to ±0.66% with beam quality factor of green laser M2=4.3.

研究了平均功率超过30 W的稳定高效全固态绿光激光器,分析得出影响全固态腔内倍频激光器倍频效率和输出稳定性的主要因素是倍频晶体局部温升造成的相位失配和热透镜效应,采用温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,降低激光器工作中倍频晶体内外温度梯度从而有效地克服因晶体局部温升造成的倍频相位匹配角失配和热透镜效应。采用三条60 W的半导体激光二极管阵列板条侧面抽运Nd:YAG激光增益介质棒,采用声光调Q,平凹直腔和腔内倍频结构配合温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,得到了稳定高效的532 nm绿光输出。在抽运电流25 A,抽运功率174.6 W时,得到了脉冲宽度110 ns,重复频率10 kHz,输出平均功率31.6 W稳定高效的绿光输出,光-光转换效率为18.1%,功率稳定性为±0.66%,绿光输出光束质量因子M2=4.3。