低温GaAs被动调Q锁模Nd∶Gd_(0.42)Y_(0.58)VO_4混晶激光器特性研究

Study on the Property of Passively Q-Switched Mode-Locked Nd∶Gd_(0.42)Y_(0.58)VO_4 Mixed Crystal Laser with GaAs Absorber Grown at Low Temperature

采用低温生长GaAs晶体作为被动饱和吸收体兼输出镜,实现了Nd∶Gd0.42Y0.58VO4混晶激光器的调Q锁模运转。研究了Nd∶Gd0.42Y0.58VO4激光器的基频运转特性。在输出镜透射率T=10%、腔长L=40 mm的情况下,当抽运功率为8.6 W时,获得激光输出功率3.78 W,光光转换效率为43.9%。并测量了Nd∶Gd0.42Y0.58VO4混晶被动调Q激光器的输出特性。实验结果表明激光器调Q运转阈值为2 W,当抽运功率为3.7 W时,激光器出现调Q锁模行为;当抽运功率为8.6 W时,激光器调Q锁模深度达70%以上,对应的脉冲包络重复频率为670 kHz,半峰全宽为180 ns,平均输出功率为1.35 W,光光转换效率为15.7%。

Passively Q-switched mode-locking Nd：Gd0.42Y0.58VO4 laser is successfully demonstrated by using a piece of GaAs crystal grown at low temperature （LT-GaAs） as the passively saturated absorber as well as the output coupler. The fundamental properties of Nd：Gd0.42Y0.58VO4 laser are investigated. At transmission of 10 % and cavity length of 40 mm, the maximum average output power of 3.78 W is obtained when the incident laser pumping power is 8.6 W, which corresponds to an optical-optical conversion efficiency of 43.9 %. The output performance is then tested for the passively Q-switched Nd：Gd0.42Y0.58VO4 mixed crystal laser. The threshold power for Q-switching and Q-switching mode-locked （QML） are about 2 W and 3.7 W respectively. At the incident laser pumping power of 8.6 W, Q-switching mode-locking pulse with modulation depth more than 70% is available. The Q-switched envelope train with repetition rate of 670 kHz is obtained with pulse duration of 180ns. The average output power and the optical-optical conversion efficiency are 1.35 W and 15.7 %, respectively.