铅蒸气受激喇曼散射的特性研究

研究了 XeCl 准分子激光在铅蒸气中的受激喇曼散射的输出能量及转换效率与其他参数的依赖关系,得到能量～120 mJ,峰值功率～2 MW 的喇曼光输出脉冲。理论分析指出了缓冲气体效应是由缓冲气体原于与铅原子的碰撞及其吸收作用的结果。     

Ba蒸气受激喇曼散射中的碰撞加宽效应

研究了缓冲气体分子所引起的Ba原子喇曼能级的碰撞加宽对于XeCl激光光泵Ba蒸气的喇曼增益系数及喇曼能量转换效率的影响。     

喇曼频移中甲烷气压对1.54μm喇曼散射红外激光输出功率下降的影响分析

在实际使用中,喇曼激光器工作4年至5年,其红外激光输出功率会明显下降(下降幅度可达到50%～70%).本文在理论上阐述了工作气体甲烷的漏气现象以及气体光分解反应是激光输出功率下降的主要原因.实验表明,随着甲烷气压的增高,喇曼频移中高阶斯托克斯光将会增强,从而抑制一阶斯托克斯光,同时甲烷气体在实验中产生光分解反应并在喇曼窗口产生沉淀污染,这些均极大地降低了输出激光的效率.针对以上问题,考虑提高喇曼盒的制作工艺以提高其密封性能,减少漏气现象,同时加入缓冲气体(如H2,He,Ar)以在一定程度上抑制甲烷的光分解反应.     

基于受激电子喇曼散射效应的红外可调谐激光系统的研究

发展红外区的连续可调谐激光器是当前激光技术及其应用的一个重要研究课题.近几年来发展了一种由金属原子蒸气中的受激电子喇曼散射效应产生可调谐相干红外辐射的方法.这种方法可将脉冲染料激光所输出的调谐的可见辐射直接转换为调谐相干红外辐射.图1为铯原子产生6S～7S喇曼跃迁的有关能级图.ω_L为泵浦光频率;7P为喇曼跃迁的近共振中间态.则斯托克斯辐射频率为:     

由连续气体激光器获得优质喇曼光谱

据美帝埃索（ESSO)研究和工程公司的化学工作者谈,用连续气体激光器作激励源,能获得优质喇曼光谱。这样,激光器就打开了用喇曼效应研究聚合物的大门。与普通的汞弧激励源相比,激光器的优点在于能提供较高水平的有用喇曼强度,而且是单色的。由于目前能产生好几种激光频率,故可挑选在萤光激励水平之下的一种频率。这就降低了以往妨碍用汞弧测量聚合物喇曼光谱的萤光强度。     

喇曼-原子力显微镜的研究进展

喇曼-原子力显微镜(Raman-AFM)是一种基于探针增强喇曼散射效应(TERS)的新型形貌表征与光电测试设备,能够在纳米尺度上对低维结构材料与器件进行喇曼研究.本文详细介绍了Raman-AFM的基本原理与关键技术特点,并展望了它的发展前景.     

喇曼散射与超喇曼散射中的压缩效应

本文重点讨论了喇曼散射与超喇曼散射非线性光学过程中的压缩效应(Squeezing Effects)。 首先写出喇曼散射与超喇曼散射非线性相互作用过程的哈密顿量,然后由海森堡方程建立场算符     

高功率光纤激光器喇曼效应的数值分析

为了研究掺镱双包层高功率光纤激光器的结构参量对喇曼效应的影响,利用数值模拟方法求解有关抽运光、激光和斯托克斯波的稳态速率方程组,得到了激光和斯托克斯波在光纤轴向的分布特性,以及喇曼阈值抽运功率与光纤激光器结构参量的关系.结果表明,当光纤激光器采用大模面积、短腔长、小斯托克斯波辐射截面和长激光波长的结构参量时,能显著提高喇曼阈值抽运功率,降低喇曼效应.     

喇曼频移激光器的光损伤研究

报道了在内腔复合镜输出方式工作下的高压甲烷气体(Nd,Ce):YAG喇曼频移激光器光损伤机制的理论分析及实验结果,提出了高重复频率工作下喇曼频移激光器解决光损伤的设计方案。     

CO2激光在气体介质中的喇曼频移

工作在10.6μm的CO2激光在军事应用中日趋重要,喇曼频移技术被广为重视.为论证其可行性,我们从受激喇曼散射理论分析出发,选择并设计了适用的激光腔,以CO2的10R(14)泵浦NH3的aP(3,1)受激喇曼线,在室温下获得aP(3,1)线的超辐射输出,从而从理论和实验两方面初步探讨了CO2激光在气体介质中的喇曼频移技术中的一些问题.     

Hydrocarbon-free potassium laser

A hydrocarbon-free alkali laser operating on a mixture of potassium vapour and helium buffer gas has been demonstrated. Hydrocarbon- free alkali lasers can operate at higher temperatures without risk of cell contamination caused by chemical reactions between the alkali atoms and the hydrocarbon buffer gas.     

Interdependence of buffer gas pressure and optimum interpulse delay in a burst-mode copper halide laser

The variation of the laser output energy of a 100 pulse burst with interpulse delay has been studied for each of the copper halides CuCl, CuBr, and CuI as a function of the tube temperature and of the buffer gas pressure for helium and neon. The tube bore was 12 mm and the specific discharge energy was 3.8 mJ ċ cm^-3. For CuI, the optimum interpulse delay decreases with increase in tube temperature and with decrease in the buffer gas pressure. At each temperature and pressure the optimum interpulse delay is shorter for helium than for neon. Although the formation of the laser pulse is intimately connected with the mechanism of breakdown in the discharge tube, the effect of this mechanism on the optimum interpulse delay is small and the latter is determined mainly by the dissociation-recombination cycle of the copper halide. The increase in optimum interpulse delay with buffer gas pressure suggests that either collisions with halogen atoms or molecules or superelastic electron collisions are responsible for the decay of the population of the metastable copper atoms.     

Atomic ion frequency standards

The history and status of trapped-ion frequency standards are reviewed. In a trapped-ion frequency standard, the frequency of an oscillator is servoed to a resonance which corresponds to a transition between two energy levels of an atomic ion. The ions are suspended in space by a combination of electric and magnetic fields. In a conventional rubidium cell, the atoms are surrounded by a buffer gas having a pressure of about 10³ Pa (approximately 10 torr). In an ion trap, the ions are held either in a vacuum or in a low-pressure buffer gas (less than 10^-3 Pa). In an atomic beam, the atoms also move through a vacuum, without collisions. However, the time available for interaction with the electromagnetic field is limited to their flight time through the apparatus, usually about 10 ms or less. Trapped ions can be observed for much longer periods. Consequently clocks based on ions trapped in electromagnetic fields portend orders-of-magnitude improvement in the development of new frequency standards. Prospects for future standards are discussed     

Density measurements of excited components in a longitudinaldischarge excimer laser

Time-dependent particle number densities of the excited components (Xe^+*, He^*) in a longitudinal-discharge XeCl excimer laser have been measured by laser absorption probing with a CW dye laser. The densities are compared with those in transversal-discharge XeCl excimer lasers. The formation dynamics of the XeCl excimer molecules, excited atoms, and excited ions are discussed. The dependence of the particle number densities of the Xe^+* ions on the buffer gas pressure, the Xe gas pressure, and the HCl gas pressure is investigated     

Resonant scattering of monochromatic light in gases

The frequency dependence of the differential cross section characterizing the resonant scattering of photons by the atoms of a dilute gas has been investigated. It is supposed that the scatterers are sufficiently dispersed so that interference between different scatterers may be neglected. Elastic collisions between the scatterers and the atoms of a buffer gas are treated in the impact approximation. A Maxwell-Boltzmann distribution of velocities is assumed. Analytic expressions for the cross section are obtained in the limits natural widthggcollision widthggDoppler width, Doppler widthggnatural widthggcollision width, and collision widthggnatural widthggDoppler width. The significance of these results is discussed.     

Temperature and Mass Factor of Buffer Gas Effect in Optically Pumped Submillimeter Wave Laser

Based on semi-classical density matrix theory and SSH theory, the effect of buffer gas in optically pumped submillimeter wave laser was theoretically studied and the effect of temperature and mass on the effect of buffer gas was analyzed, then the selection rules of buffer gas were achieved. The results could do favor to find high-efficient buffer gas of miniature optically pumped submillimeter wave laser and also had some instruction to its application.     

A continuously pulsed copper halide laser with a cable-capacitor Blumlein discharge circuit

Experimental characteristics of a continuously pulsed copper halide laser with a cable-capacitor Blumlein discharge circuit are reported. Quartz laser tubes 1 m in length and 1.5 and 2.5 cm in diameter were employed to study the effects of the electrical circuit, lasant, and buffer gas on laser performance. Measured properties of the Blumlein circuit are compared with an analytic solution for an idealized circuit. Both CuCl and CuBr with neon and helium buffer gas were studied. A maximum average power of 12.5 W was obtained with a 1.5 nF capacitor charged to 8 kV and discharged at 31 kHz with CuCl and neon buffer gas at 0.7 kPa in a 2.5-cm-diam tube. A maximum efficiency of 0.72 percent was obtained at 9 W average power. Measurements of the radial distribution of the power in the laser beam and the variation of laser power at 510.6 and 578.2 nm with halide vapor density are also reported. Double and continuously pulsed laser characteristics are compared, and the role of copper metastable level atoms in limiting the laser pulse energy density is discussed.     

缓冲气体对循环流动铯蒸汽激光器气体温度分布和输出特性的影响

为研究缓冲气体对循环流动半导体泵浦碱金属蒸汽激光器（DPAL）气体温度三维分布和输出性能的影响,将光束传播方程引入循环流动DPAL理论模型,仿真分析了高功率泵浦情况下缓冲气体配比和压强对端面泵浦横向流动铯蒸汽激光器（Cs-DPAL）输出性能的影响,获得了蒸汽池内工作气体温度的三维分布和对应的输出功率。结果表明,使用纯烷烃作为缓冲气体时,相比于CH₄,相同压强的C₂H₆对应的蒸汽池内温度更低,激光输出功率更高;使用烷烃气体和惰性气体的混合物作为缓冲气体时,若烷烃的压强较低,加入适量的He或Ar可降低蒸汽池内温度并提升激光输出功率。     

光泵远红外激光的缓冲气体的选择因素

在半经典密度矩阵理论和SSH理论的基础上,理论研究了光泵远红外激光的缓冲气体作用,分析了势阱深度和碰撞半径两个参数对光泵远红外激光系统中缓冲气体作用的影响,从而得到选择缓冲气体的规律。研究成果对寻找小型光泵远红外气体激光器的高效缓冲气体,并推动其实际应用起一定的指导作用。     

光泵亚毫米波激光缓冲气体的温度和质量

在半经典密度矩阵理论和SSH 理论的基础上,研究了光泵亚毫米波激光的缓冲气体 作用,分析了温度和质量对缓冲气体作用的影响,从而得到选择缓冲气体的规律。研究成果对寻找小型光泵亚毫米波气体激光器的高效缓冲气体,并推动它的实际应用起一定的指导作用。