激光烧蚀金属Al诱导发光的动力学研究

利用时间分辨的光谱测量技术,测定了XeCl紫外激光在不同条件下烧蚀金属Al诱导产生光谱线及其强度随时间的分布.结果表明：等离子体辐射光谱线由原子光谱线、一价离子光谱线及连续辐射背景光组成.Al原子光谱线的辐射强度与持续时间为最大,一价离子光谱线次之,以连续辐射背景光为最小.对激光烧蚀金属诱导发光的机理进行了探讨.等离子体中连续辐射背景光来自高能电子的韧致辐射和电子与离子的复合,原子光谱线和一价离子光谱线主要来自等离子体中电子与离子的复合.用此机理定性地解释了所观察到的实验现象. 关键词： 激光烧蚀 时间分辨光谱 辐射机理 金属Al     

铜蒸气激光脉冲终止机理的数值研究

建立了一个反映纵向脉冲放电激励铜蒸气激光动力学过程的自洽物理模型并进行了数值求解. 根据模拟结果深入分析了铜蒸气激光脉冲的终止机理，表明受激辐射跃迁、激光下能级的电子碰撞激发和激光上能级的铜原子经电子碰撞被抽运到更高激发能级这三个过程，是导致激光脉冲终止的重要因素. 关键词： 铜蒸气激光 激光脉冲终止机制 电子碰撞 更高激发能级     

氮离子可见区新的激光跃迁

R.A.McFarlane[1]以空气放电获得六条氮离子激光谱线 ; Heard和 Peterson[2]用汞-氮放电在可见光蓝-绿区获得氮离子激光谱线; Cheo和Cooper[3]用脉冲放电方式获得氮离子激光谱线.本文以纯氮为工作物质,采用在脉冲放电回路中串入电感,拉长放电脉宽,适当降低放电峰值电流的技术,获得五条氮一次电离态的激光新谱线:其波长分别为 648.2,464.1,462.1,460.7,460.1毫微米.并对 NII 648.2毫微米谱线,研究了其激光强度与气压的关系,进行了电流及激光脉冲波形测量.激光脉宽比电流脉宽大得多,激光产生于放电余辉中,为复合激光. 本文用脉冲轴向放电…     

光参量振荡伴生拉曼激光

利用调QNd∶YAG倍频激光泵浦KTP非线性晶体为介质的参量振荡器,产生了608.3nm~903.1nm宽带参量调谐激光,线宽1.4nm,光-光转换效率30%。当泵浦光增强到12mJ时,在参量激光谱线的近傍,长波方向出现了一条新谱线,与参量调谐激光谱线同步移动,谱线间隔随参量激光波长的增加而增加,两条谱线波数(能量)差(720cm-1)是一个定值,这是参量激光激发出斯托克斯拉曼激光典型特征。     

一种鉴别弱激光谱线的方法

在激光谐振腔内具有一定增益的激光工作物质中,往往激光和放大的自发发射(ASE)同时并存.对于其中较强的激光谱线,可以通过分光仪器分光而把它们一一显现出来.如果把激光器的谐振腔调偏或破坏掉,则这些激光谱线会立即消失,由此可证认激光谱线. 对于那些强度不足以通过分光仪器直     

锶蒸气中原子激光与离子激光的同时振荡

通过锶蒸气中的高频脉冲放电,实现了锶原子6.45μm自终止跃迁激光和锶离子1.03μm/1.09μm自终止跃迁激光的同时振荡.其中6.45μm激光最大激光平均功率为273mW.在对比实验的基础上分析和讨论了主要工作参数对这两组激光输出影响的差异.     

Sr原子M-M跃迁激光的动力学模型

建立了一个反映高频脉冲放电激励的Sr原子M-M跃迁激光的动力学模型，阐明了各激光谱线上能级的主要抽运途径：其中301μm上能级是在放电脉冲早期通过更高能级的自发辐射和激光跃迁得到布居，而另3条谱线的上能级主要是通过余辉期一价Sr离子和电子的碰撞复合以及He和三重态Sr原子的混和碰撞实现布居.定量的计算结果与实验测量结果相一致，圆满解释了各种光脉冲的时间延迟关系. 关键词： 锶原子激光 M-M跃迁 动力学模型     

碱土金属蒸气中两种不同机理的高重复率脉冲激光交替振荡现象

通过在钙、锶金属蒸气中的高重复率脉冲放电,发现钙离子和锶离子的自终止跃迁激光脉冲和碰撞辐射复合激光脉冲交替振荡的实验现象,在分析了它们激励机理异同的基础上进行了初步的实验对比研究. 关键词： 激光脉冲 交替振荡     

锶蒸气中原子激光与离子激光的同时振荡

通过锶蒸气中的高频脉冲放电,实现了锶原子6.45*!μm自终止跃迁激光和锶离子1.03*!μm/1.09*!μm自终止跃迁激光的同时振荡.其中6.45*!μm激光最大激光平均功率为273*!mW.在对比实验的基础上分析和讨论了主要工作参数对这两组激光输出影响的差异.     

脉冲放电金属蒸气激光

评述了脉冲放电激励的金属蒸气激光的发展历程和现状，根据激光发射过程，分别阐述了自终止跃迁激光和碰撞辐射复合激光的机理，报道了作者课题组最近在相关领域研究取得的新进展：包括共振－亚稳跃迁激光和复合激光的交替振荡现象，不同介质多谱线激光同时振荡现象以及碱土金属卤化物多谱线激光的实现和新发现的M－M跃迁激光。     

Excitation of low-lying nuclear states by the ion line emission in femtosecond laser plasma

A scheme of nuclear excitation by the ionic X-ray lines in laser plasma using two femtosecond laser pulses is proposed. The first pulse produces plasma with a given degree of ionization, allowing the X-ray line energies of the target ions to be tuned to resonance with the nuclear transition, while the second pulse generates hot electrons that are necessary for X-ray generation.     

激光诱导击穿铜特征谱线自吸收特性研究

应用Nd∶YAG脉冲激光器(532 nm)作为光源,诱导激发TU0Cu样品。以光栅光谱仪和ICCD为谱线分离与探测器件,在30～110 mJ激光能量范围和触发后211～230 μs时间范围内对Cu(Ⅰ)特征谱线324.754,327.396,510.554,515.324和521.320 nm的自吸收特性进行比较研究。研究表明,特征谱线自吸现象随时间增加逐渐减弱,经过5～20 μs逐步消失;在50～100 mJ能量范围内,随着激光能量的增大,谱线的自吸收程度增加,持续时间变长。同时特征谱线的自吸收特性因谱线跃迁能级状态不同而存在差异,具有相同原子组态的324.754,327.396 nm和515.324,521.320 nm两组谱线的自吸收程度随时间和激光能量的演变以及自吸持续时间随能量的变化都分别表现出相似的特征,且总角动量J较大(324.754 nm,1/2-3/2;521.320 nm,3/2-5/2)的谱线自吸收程度相对明显,持续时间较长,受能量变化影响敏感,自吸收程度随能量变化幅度也较大。谱线510.554 nm(3d104p-3d94s2)在能量小于80 mJ时自吸程度较低,持续时间较短;能量在80～100 mJ范围内时自吸程度加大,持续时间变长。     

钙离子自终止激光和复合激光同时振荡的研究

理论上分析了钙离子红外自终止激光和紫外复合激光存在同时振荡的可靠性,通过改进实验装置,首次获得钙离子的红外和紫外激光的同时振荡,二束激光输出总平均功率约70mW,其中红外和和紫外激光约各占一半。比较了不同谐振腔对激光输出特性的影响,测量并分析了激励电脉冲与所产生二束激光脉冲波形的关系。     

Spectroscopic characterization of aluminum plasma using laser-induced breakdown spectroscopy

A detailed investigation of aluminum plasma induced by a 1064 nm Nd:YAG laser in air was performed. The emission of spectral lines arising from Al I transition at 396.07 nm, Al II transition at 358.46 nm, Al III transition at 360.72 nm and Al IV transition at 363.05 nm were well-resolved. The plasma parameters including electron temperature and electron density were determined through the Boltzmann plot method using the emission line intensities of the same ionized stages of aluminum atoms and the Stark-broadening profiles of Al II emission line, respectively. The temporal evolutions of the spectral lines belonging to atomic and ionic aluminum elements and the plasma parameters were investigated at three different laser pulse energies. Moreover, the validity of local thermodynamic equilibrium was elucidated in our experimental condition.     

Strong field effect on intracavity atoms in dye lasers: Self frequency-locking

By using a variety of dye laser types and intracavity atoms, the general nature of the narrowing of the dye emission to sharp lines near atomic transition is shown. The rôle of cavity adjustment is stressed. It is suggested that this “self frequency-locking” originates from strong field effects on intracavity atomic vapors.     

Optical bistability of stimulated-emission lines in Sm(3+)-doped glass microspheres

A third-order optical nonlinear effect in a spherical glass resonator doped with Sm(3+) ions has been observed on stimulated emission lines of the (4)G(5/2)-(6)H(7/2) transition, in which the excitation beam of an Ar(+) laser in a 488-nm single line is coupled with the glass resonator through a prism. A spherical form is produced during a free fall of fractional glasses in a longitudinal electric furnace configured vertically. The prism-coupled glass microsphere exhibits sufficient performance to confine photon energy as a resonance of light inside the sphere and offers the prospect of new applications to functional photonic circuits.     

Calculation of the far-infrared spectrum of a water-vapor molecular laser

The theory of partial population inversion between vibrational-rotational states in molecular media is applied for a molecular laser using vapors of H₂O as active media. Two conditions of laser action in such media are discussed — population inversion and gain. The lines in the far-infrared at which such a laser can generate are predicted and the relative intensities of these lines, are calculated.The paper was mainly prepared during the author's stay at the University of Western Ontario, London (Ontario), Canada.     

Compact Transportable Optical Standard Based on a Single <Superscript>171</Superscript>Yb<Superscript>+</Superscript> Ion (“YBIS” Project)

The schematic diagram of the compact transportable optical frequency standard based on the quadrupole transition in a single ¹⁷¹Yb⁺ ion with a relative instability at the levelx of 5 · 10^?16, less than 1m³ in volume and less than 300 kg in weight is presented. The ionic trap and laser systems are described. Trapping and laser cooling of the ¹⁷⁴Yb⁺ ion are experimentally demonstrated.