高压H_2受激喇曼散射中二阶斯托克斯轴向分量的实验研究

受激喇曼散射含有两种物理过程,即纯受激过程和参量四波混频过程。在4～24个气压范围内,我们进行H_2的受激喇曼散射实验,报道了一阶Stokes(简称S_1)中的这两种物理过程。我们进行的反斯托克斯研究则证实它们是由相位匹配的四波混频与相位失配的四波混频组成。本文对二阶Stokes(简称S_2,波长953.6nm)进行研究,在所用实验条件下观察了它的轴向散射分量变化。     

在泵浦弄空情况下的喇曼效应

有关受激喇曼散射的理论和实验的文章是很多的,但应该指出的是关于受激喇曼散射的时间过程,特别是在泵浦弄空情况下的受激喇曼散射的时间过程的研究是不够的,而这种研究对获得脉冲宽度可调谐的喇曼激光器是十分重要的.我们利用六路亚毫微秒激光器的一束进行了此项研究,并作了一定理论分析,给出了在泵浦弄空情况下喇曼散射时间特性的结果.     

受激喇曼散射形成的过程和条件

本文按量子理论阐述了受激喇曼散射形成的过 程。认为当一束单色光照射到散射介质上时,产生受激喇曼散射的几率和自发喇曼散射的几率都存在,且两几率之比恰好等于散射光子的简并度。在介质中能否形成高亮度相干的受激喇曼散射决定于     

受激喇曼散射及其实验

受激喇曼散射(SRS)和普通喇曼散射(RS)都源于入射光子与散射分子之间的非弹性碰撞。但是,受激喇曼散射具有明显的“阈值”特征,即只有入射激光功率密度超过一定阈值才能产生“SRS”。受激喇曼斯托克斯波放大方程为     

受激喇曼后向散射波的位相复共轭特性

本文报导了受激喇曼后向散射波的位相复共轭特性的研究,实验结果表明受激喇曼后向散射波是泵浦波的位相复共轭。我们在实验上得到了由这种位相复共轭获得的泵浦波的预期的再现象。讨论了受激喇曼后向波位相复共轭散射波产生的条件。     

高阶喇曼辐射的弛豫振荡和光束特性

一、前言准分子激光器的受激喇曼散射一般采用气体作为非线性介质。对XeCl(308nm)激光,采用金属蒸气(Pb、Ba等)作为介质,进行共振受激喇曼散射,可以得到单一蓝绿波长的喇曼光。但是,XeCl在氢气中的喇曼散射,要到第3阶高阶斯托克斯喇曼频移才处于蓝绿光(499nm)。这种高阶喇曼过程不适宜用小信号注入放大形式来实现单一波长高效蓝绿光转换。本文的研究表明,采取适当的聚焦光束泵浦,用简单的单程受激喇曼超荧光放大器工作,可实现XeCl激光在氢气中单一特定蓝绿波长(499nm)占主导地位的高效喇曼转换,第三阶斯托克斯蓝绿光的量子转换效率可达ηs_1=39％,输出能量236     

受激喇曼散射与激光形成过程物理图象的比较

本文拟从受激喇曼散射作为产生高亮度相干光的一种辐射机制来进行讨论。通过与由受激辐射机制产生的高亮度相干光——激光或放大的自发辐射相对比,力图说明受激喇曼散射与激光形成的过程和条件极为相似。     

光纤中皮秒光脉冲的受激喇曼散射及光纤-光栅对激光脉冲压缩

发生在单模光纤中的最重要的两个非线性过程是自相位调制和受激喇曼散射。自相位调制是光纤-光栅对激光脉冲压缩的基础,光纤-光栅对脉冲压缩已成为实现多种波长激光脉冲压缩的主要实验技术之一。受激喇曼散射对于频率转换是有用的,但是和自相     

光纤波导中SRS和SFPM谱线间的竞争和转化

用调Q YAG激光器的倍频绿光(532nm)作为泵浦光,在掺磷锗的多模石英光纤中获得了三组不同的受激喇曼散射(SRS)和受激四光子混频(SFPM)光谱。实验表明,光纤中的SFPM过程产生的阈     

单模光纤的非线性及其瞬态耦合波方程的解

过去对光纤非线性问题的研究只就针对某一现象分别采用某一方程加以研究。本文给出了单模光纤四种非线性过程的完整的瞬态耦合波方程,并得出其解析解。这四种非线性过程包括受激喇曼散射(SRS);受激布里渊散射(SBS);非线性折射指数及自相位调制和参量四光子混频。     

高功率激光单模光纤远距离传输实验研究

受激拉曼散射（SRS）效应是制约高功率激光单模光纤远距离传输应用的瓶颈因素。采用1550nm非偏振连续波单模光纤激光器作为光源, 通过实验研究了不同注入光功率条件下经过103km单模光纤传输所产生的受激拉曼散射现象,运用级联长周期光纤光栅带阻滤波器进行了受激拉曼散射抑制实验,并进行了相应的理论分析。提出了光纤受激拉曼散射抑制有效性判据,实验演示了受激拉曼散射现象,验证了级联长周期光纤光栅带阻滤波器对受激拉曼散射抑制的有效性。     

Amplification Effect on Rayleigh Scattering and SBS in 25 km Distributed Fiber Raman Amplifier

The amplification effect on stimulated Brillouin scattering （SBS） and Rayleigh scattering in the backward pumped G652 fibers Raman amplifier have been researched. The signal source is a tunable narrow spectral bandwidth （〈10 MHz） ECL laser and is pumped by the tunable power 1427.2 nm fiber Raman laser. The Rayleigh scattering lines are amplified by fiber Raman amplifier, and Stokes stimulated Brillouin scattering lines are amplified by fiber Raman amplifier and fiber Brillouin amplifier. The SBS lines total gain is a production of the gain of Raman and the gain of Brillouin amplifier. In experiment, the gain of SBS is about 42 dB and the saturation gain of 25 Ion G652 backward FRA is about 25 dB, so the gain of fiber Brillouin amplifier is about 17 dB.     

DWDM系统中色散对受激喇曼散射的影响

研究了光纤色散对波分复用(WDM)系统中受激喇曼散射(SRS)非线性效应的影响.提出了一种简便且物理意义明确的分析计算模型,它适合于任意输入信号、任意信道数,以及不同的色散参量.基于该模型,深入分析了两信道光纤通信系统中,各种色散参量下,色散对SRS的影响,得出了色散能减小SRS效应所引起的输出功率的波动的结论,并且给出了在不同色散参量下,输出功率标准差随距离变化的曲线.     

基于拉曼晶体的多波长激光技术研究进展

利用受激拉曼散射效应,以拉曼晶体作为介质,可产生同轴输出的多波长激光信号,该种激光器具有结构紧凑、脉冲能量高和波长可调谐等特点,在全色激光成像与显示、光电对抗等领域有着重要的应用前景。本文介绍了受激拉曼散射基本原理和常用拉曼激光器结构,研究了国内外基于拉曼晶体的多波长激光技术的研究进展,总结了利用受激拉曼散射产生多波长激光存在的不足。针对目前受激拉曼散射高阶散射光较难生成,生成的多波长激光信号覆盖谱段较窄,输出功率较低,调谐方式单一等问题,提出了今后多波长激光技术发展方向。     

The effect of pulse walkoff on stimulated Raman scattering in fibers

We have experimentally investigated stimulated Raman scattering in single-mode fibers in the regime of large Raman Stokes pulse walkoff from the pump pulse by the effect of group-velocity dispersion. Measurements are made with 36 ps duration pulses at 532 nm produced from a frequency-doubled and harmonically mode-locked Nd:YAG laser. We find that for 20 percent conversion, the Raman output is produced about two walkoff lengths into the fiber as a pulse of approximately the same duration as the input pulse. We also find that the Raman pulse is produced with a strong frequency chirp.     

Theory of stimulated Raman scattering in optical fibers in thepulse walkoff regime

It is shown that the process of forward stimulated Raman scattering in a single-mode fiber, which involves the pump pulse and the first Stokes wave, is an exactly soluble problem, provided that the temporal duration of these waves is sufficiently long. The analysis takes into account the effects of pulse walkoff arising from the dispersion of the fiber as well as self- and cross-phase modulation. The procedure is applied to two examples: the first is that of stimulated Raman scattering as it builds up from spontaneous Raman emission; the second is that of launching pump and Stokes pulses     

Group Theory Approach for the Stimulated Raman Scattering in Fiber

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包层抽运掺镱光纤激光器中受激拉曼散射和受激布里渊散射效应

高功率光纤激光器大多选用掺镱双包层光纤作为增益介质,由于光纤尺寸较小,极易在光纤谐振腔中产生受激布里渊散射、受激拉曼散射效应。包层掺镱双包层光纤激光器中一旦发生受激拉曼散射和受激布里渊散射效应,其产生高强度信号成为高功率光纤激光器的主要噪声来源,影响激光输出的特性和稳定性。对包层抽运掺镱光纤激光器中的受激布里渊散射和受激拉曼散射进行了实验研究,在单模双包层光纤中观察到受激布里渊散射和受激拉曼散射。实验结果表明,在光纤谐振腔中,抽运方式、谐振腔输出镜损耗、受激瑞利散射对受激布里渊散射的影响较大,尤其是受激瑞利散射为谐振腔提供了附加反馈,不仅压窄激光信号的线宽,而且使得受激布里渊散射的阈值迅速降低。     

脉冲光布里渊散射信号的拉曼放大研究

实验研究了前向拉曼泵浦方式下脉冲信号光产生的自发布里渊散射信号和受激布里渊散射(SBS)信号的拉曼放大规律。拉曼泵浦放大自发布里渊散射信号时,随泵浦功率增大会出现SBS现象,对散射信号的放大由拉曼放大和布里渊放大两部分引起,因此增益较大,当拉曼泵浦功率为1 000 mW时Stokes光增益可达54 dB。拉曼泵浦放大SBS信号时,放大过程中只存在拉曼放大。且当泵浦功率增大至600 mW时,会引起多级布里渊散射,致使一级Stokes和泵浦能量会转移到下一级布里渊散射,一级Stokes光增益饱和并下降。     

Influence of the Stimulated Raman Scattering on the Four-Wave Mixing Process in Birefringent Fibers

The influence of the stimulated Raman scattering in the four-wave mixing process in high birefringent fibers is theoretically analyzed. We consider the dual pump configuration in both co-polarized and orthogonal polarization schemes and treat simultaneously the stimulated Raman scattering and the four-wave mixing processes. The obtained results are valid even when the shift between the pumps and signal lies inside the Raman band. Results show that when the phase-matching condition is achieved the generation of the idler wave is mostly dependent on the real part of the fiber nonlinear response function, whereas the amplification of the signal wave is mostly dependent on the imaginary part. Results also show that when the phase-matching condition is satisfied the optical power evolution of the signal and idler waves for small frequency detunings are mostly described by the anisotropic Raman response of the fiber, whereas for high frequency detunings the isotropic response dominates. Our analysis also shows that the stimulated Raman scattering can increase the efficiency of the four-wave mixing process, for certain frequency detunings.