实验验证了基于全保偏光纤的单通光参量中红外(MIR)超短脉冲产生方案。基于全光纤主振荡功率放大(MOPA)结构,获得了平均功率为2.4 W、脉冲宽度为48.85 ps、中心波长为1029.75 nm的可调重复频率近红外脉冲。当系统重复频率为100 kHz时,近红外脉冲的峰值功率可达491 kW。利用该近红外脉冲泵浦MgO-PPLN晶体,当入射脉冲的平均功率为608.9 mW时,获得了平均功率为66.13 mW的中红外皮秒脉冲,相应的峰值功率为13.5 kW。通过调控晶体的反转周期和温度,可实现3180~3976 nm的可调波长输出。该方案具有结构简单、稳定度高的特点。

在理论和实验上,分析了皮秒激光脉冲抽运所产生的参量荧光的时间相干特性。通过引入二阶复相干度,理论研究了在信号光与闲频光群速度走离存在的条件下,抽运功率和抽运脉宽对参量荧光时间相干性的影响。计算结果表明适当的抽运功率和较短的抽运脉宽是提升参量荧光时间相干性的重要条件,而过高的抽运功率或者较宽的抽运脉宽则会降低参量荧光的时间相干性。利用周期极化铌酸锂晶体,在实验上对理论结果进行了初步的实验验证。

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%.

A low-threshold middle-infrared (mid-IR) MgO:PPLN optical parametric generation (OPG) pumped by a laser diode (LD) end-pumped Z-type Nd:YLF laser at 1047 nm is realized with high reflectivity(HR) mirror for signal. At repetition rate of 10 kHz, the OPG threshold of 50 'mu'J has been achieved with HR mirror for signal. Compared with the threshold without mirror, the threshold decreases by 17%. Using HR mirror for pump at output side of crystal, the threshold of 40 'mu'J is achieved. The 2.7-4.1 'mu'm continuous tunable output is produced with seven grating periods from 28.5 to 31.5 'mu'm and temperatures from 30 to 200 . When the incident average pump power is 3 W, the OPG idler output power is 0.46 W at 3.26 'mu'm, which corresponds to optical-to-optical conversion efficiency up to 15.3%.