A periodically poled lithium niobate (PPLN) optical parametric generator (OPG) pumped by a laser diode (LD)-pumped Q-switched Tm,Ho:GdVO4 laser operated at 2.048 \mum with pump pulse of 25 ns and repetition rate of 10 kHz is reported. A continuous tunable middle-infrared (mid-IR) spectrum of 3.88~4.34 \mum is obtained by changing the crystal temperature from 50 to 124 oC. When the incident pump power is 3 W, the total OPG output power is 95 mW, corresponding to optical conversion efficiency of 3.2%.

报道了激光二极管(LD)双端面抽运Tm: Ho: GdVO4固体激光器,在2.049 μm处获得连续(CW)和准连续(QCW)激光输出。激光二极管为光纤耦合输出,光纤芯径400 μm,数值孔径0.22,输出波长805 nm。激光二极管额定输出功率27.7 W,均分为两束双端面抽运激光晶体。晶体尺寸为4 mm×4 mm×7 mm,Tm,Ho掺杂原子数分数分别为5%,0.5%。分析了Tm: Ho能级系统的主要能级跃迁和能量转换损耗。为提高激光器的输出功率和转换效率,激光晶体采用液氮制冷。在重复频率5 kHz,10 kHz,20 kHz,调Q以及连续运行模式下,获得了9.4～10.1 W的激光输出,光-光转换效率为34%～36%。最大单脉冲能量为1.9 mJ,最大峰值功率为0.13 MW。讨论了抽运光功率和重复频率对激光脉宽的影响。