Gires-Tournois干涉镜补偿色散的自启动飞秒Cr4+:YAG激光器实验研究

利用一片GTI镜补偿腔内色散,并使用宽带半导体可饱和吸收片,实现了锁模自启动的飞秒Cr4 :YAG激光输出.在9 W平均功率的1030 nm激光抽运下,获得输出脉冲功率为95 mW,光谱半高全宽45 nm,中心波长1508 nm,实测脉冲宽度为65 fs.     

超短超强激光对比度的测量研究

 为了准确地确定飞秒激光对比度的信息，基于两束不同激光的互相关原理，利用非线性晶体对激光强度变化十分敏感的特性，研制了一台三阶相关仪，并用其对钛宝石激光放大系统输出的飞秒激光脉冲进行了测量，得到了有关该系统的强度对比度的信息。结果显示：该系统输出的激光对比度在10⁶左右，在脉冲的前沿和后沿有很强的ASE辐射，并且延续了很长的一段时间；种子脉冲的对比度在10⁵左右，而且在主脉冲前约2ps的位置上，有一个强度很低的小脉冲，在主脉冲的两翼各有一个非常小的台阶。     

用SPIDER法测量超宽带钛宝石振荡器的激光脉宽研究

用SPIDER方法测量了超宽带钛宝石振荡器输出激光的脉宽，得到7.86 fs的测量结果，这是目前国内所报道的仅用啁啾镜补偿色散、直接从振荡器输出的最短激光脉冲.简要介绍了振荡器的基本结构和SPIDER方法测量装置，并对计算得到的光谱相位进行了讨论和分析.     

飞秒钛宝石光学频率梳的精密锁定

经相位锁定后的飞秒钛宝石光学频率梳已经广泛用于绝对光频的测量，这是光频标领域一个革命性的突破.在自建的90MHz飞秒钛宝石激光器的基础上首先采用光子晶体光纤将其光谱展宽到一个光倍频程，接着利用锁相环技术分别将重复频率和载波包络频移同时高精度地锁定到一台稳定度为6×10^－14的Cs钟上，进而得到了稳定度相同的飞秒光学频率梳.     

Synchronously Pumped Femtosecond Optical Parametric Oscillator Based on MgO-Doped Periodically Poled LiNbO3

We report a femtosecond optical parametric oscillator based on MgO-doped PPLN synchronously pumped by a mode-locked Ti：sapphire laser. The wavelengths of the signal and idler are continuously tuned from 1100 to 1300hm and from 2080 to 2930nm, respectively, by changing the pump wavelength and the OPO cavity length. The maximum signal output power of 130mW at the wavelength of 1225nm is obtained, pumped by 900roW of 800hm laser radiation. This corresponds to a total conversion efficiency of 22.1%. The signal pulse duration is measured to be 167fs by intensity autocorrelation with chirped mirrors for intracavity dispersion compensation.     

TEMPORAL CHARACTERIZATION OF LASER PULSES FROM JIGUANG-I LASER FACILITY WITH A COMPACT DUAL FUNCTION AUTOCORRELATOR

An optical pulse autocorrelator for rapid and slow scanning is described in this paper. Using an audio loudspeaker on one arm, an interferometric rapid-scanning signal of the output from a high-repetition laser oscillator is obtained. However, by adjusting the positions of the mirrors and using a step-motor on another arm, the intensity autocorrelation function of the output from a low-repetition laser amplifier can be easily measured. Using all-reflecting optics and an adequate nonlinear crystal, the whole instrument is very compact and has been used to measure sub-20 fs light pulses in both configurations with excellent agreement. In the slow-scanning configuration, a pulse train as long as 500ps has been determined. Using this autocorrelator, the home-made JIGUANG-I CPA laser facility was characterized for its pulse duration evolution.     

超短脉冲激光与固体靶相互作用产生的超热电子的行为研究

用几种不同的实验方法系统地研究了超短脉冲激光与固体靶相互作用产生的超热电子的行为,发现在800 nm,5×10¹⁵ W/cm2的激光与固体靶相互作用时,由于共振吸收的作用使产生的超热电子呈空间定向发射,发射的方向与等离子体对激光能量的吸收密切相关,同时超热电子的发射也与超热电子的电子能量有关,能量越高发散角越小.超热电子的能谱显示超热电子的最大能量大于500 keV,能谱结构呈双温Maxwell分布.     

Optical diagnostics of femtosecond laser plasmas

Optical diagnostics of evolution of plasmas produced by ultrashort laser pulses is carried out using a femtosecond probing beam. The time sequence of plasma shadowgrams and interferograms are obtained. The filamentation instability in high-density region induces the local density modification. Large-scale toroidal magnetic fields confine plasma expansion in the transverse direction, resulting in the formation of a plasma jet. The plasma expansion along the target normal direction is found to scale as t^1/2.     

高效率三倍频产生355nm皮秒激光的实验研究

具有高重复频率、高平均功率的皮秒放大激光在科学研究和工业生产中有着重要的应用,尤其是在脆性材料的加工领域,绿光或紫外皮秒激光具有独特的优势.基于我们研制的平均功率23.2 W、重复频率500 kHz、脉冲宽度13.4 ps的Nd:YVO_4激光器,开展了LBO晶体高效率二倍频与三倍频的研究.通过优化相位匹配和晶体内激光的走离,分别得到了平均功率12.7 W的532 nm二倍频激光和9.25 W的355 nm三倍频激光,相应的光光转换效率分别为54.7%和39.8%.激光器具有结构简单、平均功率高、转换效率高等特点,可以广泛地用于科学研究和工业生产中.     

MW级峰值功率掺钛蓝宝石激光振荡器

在常规重复频率77 MHz掺钛蓝宝石飞秒激光器的基础上,通过腔内引入Herriott型多通望远镜系统增加总腔长及对腔内色散的深入分析和实验控制,实现了低重复频率、高脉冲能量飞秒激光振荡的稳定运行.在连续功率8.2 W的532 nm激光抽运下,得到了重复频率11 MHz、单脉冲能量达72.73 nJ、对应峰值功率MW量级的结果.相对80 MHz重复频率下6.25 nJ的单脉冲能量及150 kW的峰值功率,其输出能力提高了约一个量级. 关键词： 飞秒激光 掺钛蓝宝石激光器 低重复频率 MW