25ps可见喇曼光探针

给出了受激喇曼效应中,有关脉冲压缩的主要关系式。选择适应的实验条件可以将聚焦光束受激喇曼散射脉冲压缩大于10倍。     

利用受激布里渊散射脉冲压缩效应获得高功率激光输出

 讨论了利用受激布里渊散射效应实现高功率激光脉冲压缩的基本原理,并做了相应的数值摸拟计算。利用星光Ⅱ装置进行了脉冲压缩的原理性实验,获得了约60％的能量转换效率和近4倍的压缩比。     

水中受激布里渊散射脉冲的反常压缩

受激布里渊散射(SBS)具有脉冲压缩的特性,受激布里渊散射的脉冲宽度随着抽运能量的增大而变小,在水中可以达到几百皮秒的量级.本文在实验上观察到一种受激布里渊散射的脉冲宽度随抽运能量增大而变大的现象,这里称之为反常压缩.SBS的脉冲反常压缩和脉冲压缩与抽运光的强弱会聚情况有关.利用数值模拟,模拟了强弱会聚情况下抽运光在水中的传输规律,强弱会聚情况的抽运光对受激布里渊散射形成的有效增益长度不同:抽运光强会聚时有效增益长度短,形成SBS脉冲宽度的反常压缩;弱会聚时有效增益长度长,也就是正常的SBS脉冲压缩.     

受激布里渊散射介质CCl4中脉冲传输与功率限幅特性

分析了受激布里渊散射介质CCl4对纳秒激光脉冲的传输特性及功率限幅特性. 结果表明：透射脉冲波形随抽运光能量增加而压缩变形，脉冲前沿保持高斯型，后沿被压缩成功率“平台”，功率“平台”随抽运脉冲能量增加而逐渐变宽，但功率水平不变，表明该光学系统具有的功率限幅特性. 详细分析了功率限幅特性随抽运能量的变化规律和时间响应特性规律，采用脉宽为10ns、波长为1.06μm的Nd:YAG激光脉冲进行实验验证，理论与实验结论相符合.  关键词： 受激布里渊散射 功率限幅     

利用相位共轭镜产生高质量宽度可调脉冲

实验研究了双池受激布里渊散射系统中的脉冲压缩。通过简单地改变双池间距可以获得脉宽可调的优质光束,脉宽可调范围依赖于抽运能量。增大抽运能量,脉宽可调范围也相应地增大。对双池受激布里渊散射系统的脉冲波形进行了数值模拟,理论计算结果与实验符合得很好。     

利用受激布里渊散射获得皮秒激光脉冲

 采用两级布里渊结构压缩8ns的Nd：YAG激光，研究了基频光和倍频光的受激布里渊散射（SBS）压缩过程。实验中采用四氯化碳作为SBS介质，经第一级双池SBS压缩后，获得了1.5ns左右的Stokes 脉冲；第二级采用单池SBS压缩，分别使用基频光和倍频光作为泵浦光，获得了最短为60ps 的Stokes脉冲。实验证明，在一定条件下，利用SBS压缩脉宽可以获得比介质的声子寿命更短的脉冲。     

SBS作相位共轭谐振腔的研究

用受激布里渊散射（SBS）作为相位共轭腔，同时兼起调Q脉冲压缩作用，得出了在不同聚焦参量下脉宽压缩的结果。     

KrF激光脉冲整形研究

 实验研究了脉冲堆积法对KrF激光的整形能力。利用受激布里渊散射(SBS)压缩脉冲获得了脉宽为3~5 ns的短脉冲，用4束激光堆积获得了脉宽为10~15 ns、平顶宽度为5~10 ns的整形脉冲。利用实测SBS脉冲数据，对脉冲堆积法进行了数值模拟，模拟的脉冲宽度为12.7 ns，平顶宽度为7.7 ns，该结果与实验相符。对脉冲堆积法的任意整形能力进行了模拟，讨论了脉冲宽度变化对整形的影响，发现脉宽变化在5%以内时，对整形脉冲的影响较小。对整形脉冲的放大进行了定性研究，结果表明：平顶脉冲通过放大器后，前沿部分放大较多，由于饱和作用，后沿放大较少；如果前端整形脉冲前沿为斜坡状，放大后可以得到近平顶的脉冲。     

受激喇曼散射对自相似脉冲产生的影响

研究了在受激喇曼散射与三阶色散共同作用下,自相似脉冲在具有正常色散的色散渐减光纤中的演化情况.结果表明:在同一个传输距离上,当考虑受激喇曼散射与三阶色散的共同影响时,脉冲中心的不对称特性相对好转;产生中心漂移与边缘振荡较只有三阶色散作用时要减弱,啁啾仍然具有很强的线性特性,但是线性范围减小,导致频谱的窄化以及对接下来自相似脉冲的压缩产生了不利影响;而且光纤长度的延长并没有起到展宽啁啾线性范围的效果,反而导致严重的啁啾非线性;因此对脉冲进行压缩后,压缩脉冲质量较不考虑受激喇曼散射时要差.     

双级受激布里渊散射压缩获得高质量窄脉冲波形

针对受激布里渊散射(SBS)脉冲压缩系统中经常出现的波形调制现象,提出一种抑制调制、改善窄脉冲波形质量的新方法——双级SBS脉冲压缩结构。此方法以"两次压缩,子峰能量主峰提取"为控制手段,能够解决输出脉冲的多峰调制问题,有望成为获得高压缩比、高质量窄脉冲的一种新途径。提出并建立双级SBS脉冲压缩系统物理模型和数值计算模型,并利用典型SBS介质CCl4和FC-72开展了实验研究,获得无调制单峰结构的压缩脉冲,并与理论模拟结果符合较好。     

圆柱对称光脉冲在负色散克尔介质中的传输

利用变分法得到了任意光脉冲传输的一般特性及高斯光脉冲压缩（或扩展）的必要条件，这说明在一定初始条件下时空非对称的光脉冲也可形成“光子弹”，在某些区域内，通过时空耦合作用，光束的空间会聚可以导至脉宽的压缩。     

Author index to volume 54

It has been experimentally shown that when light pulses propagate in active neodymium glass fibers, a decrease of amplified pulse length almost by a factor of two is observed at a fiber length of 1 m. The study of the amplification process of an ultrashort laser pulse train by a glass fiber quantum amplifier showed that the main reason of the nanosecond light pulse compression is a recombination of the short-lifetime colouring centers due to the absorption of the front of the light pulse. Experimental results are presented concerning light pulse compression at various excitation levels of active glass fibers.     

200 Hz高重复频率SBS脉宽压缩实验研究

受激布里渊散射(SBS)脉宽压缩是实现高峰值功率、短脉冲激光输出的重要途径之一,然而,目前SBS脉宽压缩仅限于1~10 Hz低重复频率激光器,限制了高重频短脉冲激光器在激光雷达、空间碎片探测以及目标成像等领域的应用。基于此,开展了高重复频率下的SBS脉宽压缩实验研究。设计搭建了高重复频率的主振荡放大激光器,开展了SBS二次级联脉宽压缩和SBS振荡放大双池脉宽压缩实验。通过SBS二次级联压缩实现了脉冲宽度从~32 ns压缩到~1.9 ns,脉宽压缩比达16倍;而通过SBS振荡放大双池结构实现了脉冲宽度从~4 ns压缩到376 ps,脉宽压缩比达10倍。实验结果表明,采用该超净封闭型SBS相位共轭镜,在Stokes光输出能量达50 m J时,无光学击穿现象,实现了在200 Hz高重复频率下的SBS脉宽压缩。     

介质参数对受激布里渊散射脉宽压缩的影响

 利用KrF激光和SF₆介质从理论和实验上研究了声子寿命和增益系数等介质参数对SBS脉宽压缩比和能量反射率的影响。理论上采用一维瞬态模型对SBS过程进行数值模拟，考虑了瞬态过程、介质吸收以及泵浦耗空的影响，计算了SBS介质不同参数对脉冲压缩影响的规律。实验表明，在实验参数的变化范围内声子寿命越短、增益系数越小，越有利于脉宽压缩。在0.68MPa下，脉宽压缩比达到8。数值模拟了声子寿命和介质增益系数单独变化时对SBS过程影响的规律，发现在声子寿命和增益系数同时变化时，SBS对泵浦脉冲的压缩有最佳点。     

Stimulated Brillouin scattering phase conjugation of light beams carrying orbit angular momentum(Invited Paper)

We investigate the stimulated Brillouin scattering(SBS)properties of light beams carrying orbit angular momentum(OAM).The phase conjugation of light beams carrying OAM is experimentally achieved in an SBS mirror with a random phase plate.The spectrum and the pulse width compression of SBS light are measured.It is shown that the phenomena of pulse compression is observed and OAM conservation is confirmed in the SBS process.The OAM transfer from photons to phonons may find potential applications in photon-phonon conversion-based signal-processing schemes by using OAM multiplexing.     

Characteristics of perfluorinated amine media for stimulated Brillouin scattering in hundreds of picoseconds pulse compression at 532 nm

The characteristics of stimulated Brillouin scattering(SBS) in perfluorinated amine media and the experimental structure used in hundreds of picoseconds pulse compression at 532 nm are demonstrated. A two-stage SBS pulse compression structure is adopted for this work. The compact double-cell SBS compression structure and the scattering media FC-70 are chosen to compress the incident light from 9.5 to about 1 ns in the first stage. Then,the light is used as the pumping source for the second pulse compression. In the second stage, using a single-cell SBS structure in a pulse compression system, perfluorinated amine media with different phonon lifetimes, such as FC-3283, FC-40, FC-43, and FC-70, are chosen to run the comparative experimental study. The narrowest compressed pulse times obtained are 294, 274, 277, and 194 ps; they respectively correspond to the above listed media. The average width of the compressed pulse width is 320 ps for FC-3283, with a fluctuation range of87 ps. For FC-40, the average pulse width is 320 ps, with a fluctuation range of 72 ps. And for FC-43, the average pulse width is 335 ps, with a fluctuation range of 88 ps. However, the average pulse width is only 280 ps for FC-70, with a fluctuation range of 57 ps. The highest energy reflectivity is more than 80% for all of the media. The experimental results show that a two-stage SBS pulse compression system has lower pump energy requirements, thus making it easier to achieve a compressed pulse waveform. The results also show that the shorter the phonon lifetime of the medium, the narrower the obtained compressed pulse width.     

Stopping light all optically

We show that light pulses can be stopped and stored coherently, with an all-optical adiabatic and reversible pulse bandwidth compression process. Such a process overcomes the fundamental bandwidth-delay constraint in optics and can generate arbitrarily small group velocities for any light pulse with a given bandwidth, without any coherent or resonant light-matter interactions. We exhibit this process in optical resonators, where the bandwidth compression is accomplished only by small refractive-index modulations performed at moderate speeds.     

Chirping effects accompanying light pulse shortening by nonlinear amplification and saturable absorption

This paper studies theoretically several mechanisms responsible for light pulse compression in femtosecond dye amplification chains. Compression arising from reshaping of both the intensity profile and the phase of the propagating pulse is investigated. A compression factor of the order of 2 can be achieved only in the case of combined interaction with an amplifier and an absorber.     

Adaptive dispersion compensation for remote fiber delivery of near-infrared femtosecond pulses

We report on remote delivery of 25-pJ broadband near-infrared femtosecond light pulses from a Ti:sapphire laser through 150 m of single-mode optical fiber. Pulse distortion caused by dispersion is overcome with precompensation by adaptive pulse shaping techniques, while nonlinearities are mitigated by use of an SF10 glass rod for the final stage of pulse compression. A near-transform-limited pulse duration of 130 fs was measured after the final compression.