共查询到19条相似文献,搜索用时 250 毫秒
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非共线相位匹配LBO晶体飞秒光参变放大器的研究 总被引:7,自引:3,他引:4
对非共线相位匹配LBO晶体飞秒光参变放大器进行了系统地分析和理论研究,用数值方法得出了非共线角、相位匹配角、增益和增益带宽之间的关系,给出了放大器设计的各种最优化参量。研究结果表明,这种参变放大器不仅可以实现较高的参变增益和获得极宽的增益带宽,还具有较大的参变允许角、较小的走离角和小的群速色散。因此这种参变放大器对于以纳秒级高功率激光作为抽运光,利用光参变啁啾脉冲放大(OPCPA)技术高效率参变放大飞秒脉冲产生10^12W甚至10^15W级的超强超短激光脉冲具有重要的意义。建立的理论模型具有普遍意义,也为其他类似的参变过程提供了重要的理论依据。 相似文献
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研究了一类非线性尘埃等离子体孤波解. 首先构造一个变分迭代, 其次决定系统的初始近似, 最后通过变分迭代方法得到了对应模型的各次近似解.
关键词:
等离子体
变分迭代
近似解 相似文献
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窄线宽纳秒脉冲光纤拉曼放大器在非线性频率变换、遥感探测和量子信息等领域有广泛的应用前景.综合考虑受激拉曼散射(stimulated Raman scattering,SRS)、受激布里渊散射(stimulated Brillouin scattering,SBS)、自相位调制(self-phase modulation)和交叉相位调制(cross-phase modulation)等非线性效应,建立了窄线宽纳秒脉冲光纤拉曼放大器的非线性动力学模型.仿真分析了放大器中脉冲激光的时频演化特性,对比研究了抽运脉冲宽度、光纤长度和信号光功率等因素对放大器性能的影响.研究发现,上述因素会影响放大器的SRS阈值、SBS阈值、输出激光线宽、激光转换效率等.例如,当脉冲宽度为800 ns时,SBS随着抽运功率的增加而发生,限制了激光功率的提升;减短抽运脉宽可以抑制SBS,但是输出激光的线宽易于展宽到数百MHz以上;增加光纤长度可以获得更低的SRS阈值和更高的转换效率,但是SBS效应和光谱展宽程度也随之增强.系统搭建中需要平衡各非线性效应,选择合适的系统参数.研究内容可以为窄线宽纳秒脉冲光纤拉曼放大器的设计搭建提供参考. 相似文献
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高峰值功率大模场全光纤脉冲放大器 总被引:3,自引:3,他引:0
报道了一种由纤芯直径分别为15μm和25μm的大模场光纤组成的全光纤脉冲放大器模块.当注入脉冲宽度为10 ns,重复频率为1 Hz.光谱宽度为0.3 nm,脉冲能量为80 nJ的激光脉冲时,经过两级放大输出的激光脉冲峰值功率为30 kW,单脉冲能量为300μJ.此外,实验研究了该放大器模块输出的时间特性.研究发现:由于受激布里渊散射(SBS)效应,限制了单纵模光纤激光在光纤中的高能量放大,采用宽带激光脉冲可以有效地抑制SBS效应,提高光纤放大器的SBS阈值. 相似文献
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报道一种全固化、全光纤的用于高功率激光驱动的惯性约束聚变驱动器的光脉冲产生系统,采用单纵模振荡器输出连续激光信号,经过相位调制器和振幅调制器,得到一个时间波形上已整形且具有一定带宽(约0.1 nm)的激光脉冲,经光纤放大器放大并经光纤分束器分束后同时输出四路激光脉冲,各路激光脉冲先通过时间同步调整单元精确控制时间同步关系后,经可编程光纤衰减器调节各路之间的功率平衡后再通过光纤放大器做进一步放大并通过150 m光纤传输输出至预放系统.该光纤系统可输出0.3—20 ns、带宽0.1 nm、能量数纳焦的几乎任意
关键词:
激光聚变驱动器
前端
光纤激光系统 相似文献
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建立有限元模型,通过求解瞬态辐射传输方程模拟短脉冲激光在半透明介质中的传输.针对散射占优性半透明介质内辐射传输求解效率较差的问题,采用扩散综合加速迭代算法,提高计算效率,缩短计算时间.结果表明:采用精确解析式描述脉冲激光散射源项的求解策略可以获得准确的计算结果,精确地模拟快速变化的波前,不会产生数值扩散和数值振荡.此外,扩散综合迭代算法的计算时间仅为源项迭代的50%~60%. 相似文献
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超短脉冲激光系统中,足够宽的带宽是获得超短脉冲的先决条件.高增益放大器,特别是再 生放大器的增益窄化效应严重制约着输出激光脉冲的时间特性.将可编程声光色散滤波器(AO PDF)应用到高功率激光系统中,能有效地克服增益窄化效应.实验表明,再生放大器的光谱 宽度由未应用前的27?nm增加到了44?nm,压缩脉冲的宽度减小了一半,从而也使峰值功率 提高了一倍.
关键词:
超短脉冲
增益窄化
光谱整形
可编程声光色散滤波器 相似文献
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The adiabatic nuclear and electronic sampling method (ANES), originally formulated as an efficient Monte Carlo algorithm for systems with fluctuating charges, is applied to the simulation of a polarizable water model with induced dipole moments. Structural, thermodynamic and dipolar properties obtained by ANES and a newer algorithm, the pair approximation for polarization interaction (PAPI), are compared with full iteration. With the best parameters, the inaccuracy of both approximate methods was found to be comparable with the uncertainty of the full iteration. The PAPI method with iteration radius equal to the second minimum of the oxygen—oxygen correlation function is, depending on the convergence tolerance, 10–15 times faster than the full iteration for 256 molecules, and yields very accurate structure and thermodynamics with deviation about 0.3%. When the iteration radius is increased to the cutoff distance, exact results are recovered at the cost of decreased efficiency. The ANES method with small nuclear displacements proved to inefficiently sample the configurational space. Simulations at low electronic temperatures with large nuclear displacements are inaccurate for up to 100 electronic moves, and increasing this number would make the simulations as slow as the full iteration. The most accurate and efficient adiabatic ANES simulations are those with infinite electronic temperature, large nuclear displacements and 1–10 electronic moves. The extra freedom of induced dipoles in the ANES method at high electronic temperatures modifies the observed dipolar properties; however, the question of whether the dielectric constant is also modified needs further consideration. 相似文献
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Variational iteration method for solving perturbed mechanism of western boundary undercurrents in the Pacific 总被引:9,自引:0,他引:9 下载免费PDF全文
A class of perturbed mechanisms for the western boundary
undercurrents in the Pacific is considered. The model of generalized
governing equations is studied. Employing the method of variational
iteration, an approximate solution of corresponding model is
obtained. It is proved from the results that the solution for the
variational iteration method can be used for analysing operation of
the perturbed mechanism of western boundary undercurrents in the
Pacific. 相似文献
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O. Kuzmanovska-Barandovska O. Atanackovi? 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(5):708-722
The iteration factors method (IFM) developed in Paper I [1] (Atanackovi?-Vukmanovi? and Simonneau, 1994) to solve the NLTE line transfer problem for a two-level atom model, is extended here to deal with a multilevel atom case. At the beginning of each iteration step, for each line transition, angle and frequency averaged depth-dependent iteration factors are computed from the formal solution of radiative transfer (RT) equation and used to close the system of the RT equation moments, non-linearly coupled with the statistical equilibrium (SE) equations. Non-linear coupling of the atomic level populations and the corresponding line radiation field intensities is tackled in two ways. One is based on the linearization of the equations with respect to the relevant variables, and the other on the use of the old (known from the previous iteration) level populations in the line-opacity-like terms of the SE equations. In both cases the use of quasi-invariant iteration factors provided very fast and accurate solution. The properties of the proposed procedures are investigated in detail by applying them to the solution of the prototype multilevel RT problem of Avrett and Loeser [2], and compared with the properties of some other methods. 相似文献