铜蒸气激光泵浦的染料激光器中的ASE分析

对铜蒸气激光器横向泵浦的染料激光器中的ASE特性进行了研究。在理论上,考虑染料光强的时间、空间变化关系和光谱分布以及上能级粒子数的时间、空间变化,用计算机进行差分求解,得到ASE光强、光谱分布随泵浦光强的变化,得出了不同波长ASE光的脉冲宽度的不同结果,对增益的空间分布也进行了计算。在实验上,用平均功率5W的铜蒸气激光器泵浦R6G的酒精溶液,染料在染料盒中快速流过泵浦区。测出ASE强度随泵浦光的变化关     

基于电光开关的增益控制法准分子激光ASE抑制技术研究

在高功率准分子激光系统中,由于介质的高增益和非存储特性,自发辐射放大(ASE)成为影响系统输出对比度的关键因素。在角多路主振荡功率放大器(MOPA)激光放大链中,为抑制ASE,采用了电光开关和增益控制相结合的方式,在第一放大级后置入了电光削波开关,并利用检偏器另一偏振分量作为控制光束,对下一放大级进行增益控制。构建了光路,进行了原理性实验研究,并在第二预放大级中获得了40300…1的信号对比度。采用该方法的优点是在主光路中引起的能量损耗小,且降低了对破坏阈值的要求。电光开关和增益控制相结合共同实现了前两级预放大器的ASE抑制。     

类锂离子软X射线激光实验研究

在上海光机所6路激光装置上成功地进行了软X射线激光增益实验,利用自制的一维空间分辨掠入射光栅光谱仪研究了1mm厚平板靶激光等离子体中铝和硅的类锂离子的自发发射放大(ASE)性能.实验表明,Al~(10+)离子的5f-3d跃迁(波长10.57nm)的时间积分发射强度随线状等离子体的长度非线性增长,相应的增益系数为2.3±0.7cm~(-1),最大增益长度乘积约为2; 空间分辨光谱显示增益最大的区域离靶面约440μm.     

离子通道激光

离子通道激光(ICL)是一种可工作在紫外和X射线区的新型自由电子激光。本文对低增益情况下ICL的辐射放大机制进行了研究。利用Madey理论导出了ICL的增益公式;通过群聚参量Bi对ICL中电子的两种不同的群聚机制进行了讨论;由谐振条件得出了ICL的输出频率,并与回旋自谐振脉塞(CARM)和常规自由电子激光(FEL)进行了比较。     

染料激光的三维超辐射

一.引言 通常所说的受激辐射大多是一维的。随着高增益染料激光的发展,二维的平面染料激光和超辐射也已有报导,但三维染料激光和超辐射则未见报导。1980年,Z.Fy.Hor Vath等人虽曾提出三维的“球形激光”,但迄今未看到实验报导。我们在实现染料激光的扇面超辐射的基础上,对染料激光的三维超辐射(下面简单写作ASE)作了尝试,并初步得到有趣的实验结果。     

单模激光的噪声关联时间效应

利用线性近似方法推导了由关联噪声驱动的单模激光增益模型的光强关联函数、关联时间和功率谱,分析讨论了噪声互关联时间τm和自关联时间τs对激光上述性质的影响,发现在关联噪声驱动的单模激光系统中,τm和τs对激光统计性质起着完全不同的作用,并导致一些新奇的现象.     

小信号双级染料激光放大器的优化设计

利用染料激光放大器的横向稳态抽运理论，研究了小信号双级染料放大器的抽运能量分配以及染料池长度的选取对激光增益的影响。对于其他参量确定的放大系统，存在着最佳的抽运能量分配比例和最佳的染料池长度的选取方法。通过自编程序的计算，可方便地找出特定系统染料池长度和抽运能量分配比例的最佳值。     

具有特定光强分布的激光表面硬化技术

利用光束变换技术得到不同光斑形状和不同强度分布的光束,可满足表面硬化所需要的硬化层均匀性等要求.激光硬化在材料表面产生的实际效果与光强分布密切相关,利用特定光强分布的光束进行激光硬化可以得到所需要的温度场及组织分布,直接影响材料表面硬化的效果.对高斯光束圆光束、平顶矩形光束、曲边矩形光束、点阵光斑等不同强度分布的激光表面硬化(LSH)技术进行了介绍.硬化层特定的硬度分布及组织结构等硬化效果是特定光强分布激光束与材料相互作用的结果,要获得所需硬化效果,则需要利用反求方法设计与硬化效果相对应的特定光强分布的光斑.给出了特定光强分布的激光表面硬化技术的发展趋势.     

激光尾场电子加速器驱动的全光学FEL物理模拟研究

对中国科学院上海光学精密机械研究所(SIOM)即将开展的基于激光尾场加速(LWFA)电子束的自由电子激光(FEL)实验(SIOM-FEL)进行了数值模拟研究,提出利用直接外种子激光驱动的方案来获得FEL辐射。理论和仿真结果表明,采用直接外种子激光驱动模式,在束流能散为1%,发射度为0.3mm·mrad的情况下,提高峰值电流强度到10kA可以得到接近200倍增益的FEL辐射,而利用具有横向梯度的波荡器也可以在较低的束流强度条件下获得较高的辐射增益。     

染料液晶同激光的非线性光学效应研究

本文研究了激光同染料液晶的非线性光学效应。理论分析了激光在染料液晶中的传输过程,分别计算了当入射激光功率为10mW/cm2和50mW/cm2时的输出激光光强分布。实验测量了532nm连续激光通过染料液晶传输后的光限幅曲线,观察了输出激光光斑形状随入射激光光强的变化,实验结果与计算结果基本相吻合。     

Amplified spontaneous emission (ASE) in laser oscillators and amplifiers

Dye-laser oscillators and amplifiers are studied theoretically with inclusion of amplified spontaneous emission (ASE). Assuming pencil-like geometry in both cases, laser signal intensity and ASE intensity are described with appropriate photon-transport equations. In particular, there exist different boundary conditions fox both fluxes in the laser cavity case due to the different feedback behavior of an optical resonator for laser modes and ASE modes. The interaction of laser output and ASE intensity is discussed in detail, including laser output optimization without and with ASE effects. For single- and double-pass amplifiers closed-form solutions for gain saturation due to input signal and ASE flux axe also given. More complicated gain functions, such as inclusion of reabsorption in dye lasers, are also treated in some detail.     

大型KrF放大器中的放大自发辐射

设计了大型ＫｒＦ准分子激光器放大自发辐射的三维和准三维计算程序，比较了两种方法的差别。通过对不同纵横比、增益吸收比及注入光强条件下，放大自发辐射（ＡＳＥ）及提取效率的计算，明确了影响提取效率的主要因素．当注入强度为０．１饱和光强时，其噪信比（ＡＳＥ强度与相干光输出强度比）约为５％。     

Theoretical and experimental investigation of a thin-film waveguide laser amplifier with a lossy cladding

In laser amplifiers using high gain materials such as dyes or semiconductors, the inherent broad-band amplified spontaneous emission (ASE) may strongly saturate the amplifier gain: this yields a severe limitation on the amplification of small signals. We show that this difficulty can be appreciably overcome in an optical waveguide amplifier with a lossy cladding. A theoretical analysis of gain saturation by the ASE noise in a lossy cladding waveguide amplifier is given, and the small-signal gain improvement is stressed. An experiment involving a metal-clad thin-film dye laser amplifier is reported, the results of which are in agreement with the theoretical predictions.     

Power scaling in quantum-well laser amplifiers

The effects of increasing excitation on the performance of quantum-well semiconductor laser amplifiers were investigated. Amplified spontaneous emission (ASE) and gain roll over at high injected carrier densities are two limitations to the power scaling of these devices. A Rigrod analysis was used to study the effects of these limitations on the gain, ratio of signal to ASE power, and efficiency for different values of injection current, facet reflectivity, and input laser intensity. Comparisons are made with an equivalent amplifier operating with a bulk semiconductor gain medium. This analysis suggests that quantum-well semiconductor amplifier performance improves with a double-pass configuration     

Amplified spontaneous emission effects in semiconductor laseramplifiers

The analysis presented provides a quantitative method for predicting semiconductor laser amplifier performance in the presence of ASE (amplified spontaneous emission). It indicates that in order to increase the fraction of pump power that contributes to the amplification of the input laser field relative to that spent in overcoming internal losses, an amplifier should operate at as high an excitation level as possible. This may mean operating an amplifier above its free-running oscillation threshold. A limitation to the maximum pump power is the increase in ASE. With too high an excitation, ASE dominates over the amplified input laser field, resulting in a quenching of the amplifier gain, efficiency and coherence. ASE effects may be mitigated by increasing the input laser intensity, decreasing the amplifier facet reflectivities, or, in some cases, tuning the master oscillator so that it is resonant with the amplifier. The analysis indicates that minimizing the facet reflectivity is the most effective way to circumvent ASE limitations to power scaling semiconductor laser amplifiers     

染料放大器的ASE和飞秒脉冲放大

分析了染料放大器(DLA)的放大的自发辐射(ASE)的分布、上能级以及三重态粒子数分布。用数学方法模拟计算了泵浦作用时非饱和情形下染料分子的储能和飞秒脉冲的放大。我们认为,设计一个染料放大器必须考虑三重态积累对分子储能的影响。用调Q倍频Nd∶YAG脉冲同步泵浦染料二级放大器放大飞秒脉冲,得到的第一、二级放大倍数分别为1000和60,对于第一级放大,计算结果与实验结果基本相符。     

SCDL振荡放大系统单模及双模运转的特性

本文报道对短腔染料激光(SCDL)振荡放大系统单模工作及双模工作时输出的光谱特性和运转性能的研究,观测了放大器放大自发发射(ASE)及系统调谐特性,讨论了系统ASE及其不稳定性等问题及其解决的措施。     

一种准分子激光泵浦的微微秒染料激光脉冲放大器

本文叙述一种在一个泵浦周期内讯号脉冲三次通过染料池的微微秒激光脉冲放大器,它有效地利用泵浦能量,可以得到4×10~4的高增益,低的放大自发荧光以及没有脉冲变宽,并且结构简单,工作稳定。用四能级分子模型,以及作速率方程的数值解,对放大器的特性做了计算机模拟。计算与实验结果相符。     

Amplified spontaneous emission and signal amplification in dye-laser systems

Transversely pumped dye-laser systems are investigated theoretically and experimentally. A set of coupled rate equations for the excited-state population densities and for the photon fluxes in both directions, at all wavelengths, is presented. Both the temporal and spatial dependence of these quantities are accounted for. The equations are solved numerically for a variety of practical situations, and analytical approximations for some limiting cases are discussed. The results describe the dependence of the amplified-spontaneous-emission (ASE) output flux on pumping rate, the spectral narrowing process, and the effects of gain saturation. It is found that under practical laboratory conditions the gain of such dye systems saturates rapidly. Consequently, at high pumping rates the output varies linearly with pump intensity, and the conversion efficiency from pump to ASE photons approaches unity. The performance of dyedaser amplifiers is described by the same set of equations, and the gain characteristics of such systems are analyzed as a function of input signal intensity and pumping rate. The theoretical calculations are compared with the results of a set of experiments, and good agreement is found. The operation characteristics of a dye-laser amplifier are evaluated and utilized in the design of a narrow-band oscillator-amplifier system.     

激光泵浦平板染料波导的“被导”和“自导”特性

本文实验观测了N_2激光泵浦平板染料波导的各种“被导”和“自导”特性,双程染料池在x方向是“被导”的;在y方向是“自导”的。