33 W quasi-continuous-wave narrow-band sodium D_(2a) laser by sum-frequency generation in LBO

We demonstrate an all-solid quasi-continuous-wave （QCW） narrow-band source tunable to sodium D2a line at 589.159 nm. The source is based on sum-frequency mixing between lasers at 1064 nm and 1319 nm in a LBO crystal. The 1064 nm and 1319 nm lasers are produced from two diode side-pumped Nd：YAG master oscillator power amplifier （MOPA） laser systems, respectively. A 33 W output of 589 nm laser is obtained with beam quality factor M^2 = 1.25, frequency stability better than ±0.2 GHz and linewidth less than 0.44 GHz. A prototype 589 nm laser system is assembled, and a sodium laser guided star has been successfully observed in the field test.     

表面电磁波

一、引 言 近几年来,表面物理的研究引起人们的很大重视.与此同时,对表面电磁波的兴趣也随之增加起来.我们这里所说的表面电磁波,是指表面极性元激发与电磁波(光子)的耦合模即表面极化激元波(surface polaritons),它沿着两种介质之间的界面以准波的形式传播。其振幅随着远离界面指数式迅速衰减.也就是说,波被“束缚”在界面上.以铜一空气界面为例,当入射激光波长是10.6um时,表面电磁波沿界面的传播长度为1.9cm,而它在金属内的穿透深度仅为250A,即传播长度是穿透深度的7.6×105倍.依照不同的界面条件,极性元激发可以是光学声子、激子、等离…     

GaAs/AlxGa1-xAs超晶格子带间光跃迁的研究

运用Kronig-Penney模型的新形式,研究了超晶格子带间光跃迁的频率、带宽和跃迁强度,用GaAs/Al_xGa_1-xAs多量子阱材料做了关于红外吸收的实验,理论与实验符合较好。 关键词：     

隧穿展宽对超晶格子带间光吸收饱和的影响

本文运用Kronig—Penney模型新形式,研究超晶格子带间光吸收的三阶非线性效应,发现不论量子阱参数(如阱宽、垒宽和垒高等)如何改变,光吸收饱和强度与隧穿谱宽之间存在着一种较普遍的关系,并阐明了这种依从关系的物理机制。     

首次观测到内壳层跃迁的双光子X射线发射

人们已经广泛地研究过亚稳态的类氢和类氦系统,这些亚稳态既可以通过双光子电偶极跃迁衰变,也可以通过单光子磁偶极跃迁或磁四极跃迁而衰变。 最近,以色列 Bar-Ilan大学的 Bannett 和 Fre-und[1]报告,他们首次观测到了来自单电子内壳层跃迁的双光子X射线发射.当然,在多电子原子     

High-Average-Power Third Harmonic Generation at 355 nm with CsB3O5 Crystal

A 17.7W average power output at 355nm by the third harmonic generation (THG) of 1064nm light has been obtained with the nonlinear optical crystal CsB305 (CBO). The fundamental light source is a diode-pumped Nd:YAG laser with a pulse duration of 70ns and a repetition rate of 7kHz. A CBO crystal cut for type-Ⅱ PM angles is used in the experiment. The THG energy conversion efficiency with CBO is twice as large as that with LBO. As a THG crystal, CBO has better performance than that of LiB305 crystal (LBO).     

参量自注入放大产生皮秒中红外脉冲

首次采用参量自注入放大方法产生了皮秒中红外超短脉冲．该方法的优点是仅使用１块红外非线性晶体，实验装置简单，成本低．入射光源是锁模皮秒Ｎｄ：ＹＡＧ激光器，用来泵浦ＡｇＧａＳ２单晶，经过参量过程辐射３—１０μｍ的皮秒脉冲激光．最大红外脉冲激光输出能量为１４μＪ．     

Beam divergence effects on high power optical parametric oscillation

The beam divergence effects of the input pump laser on a high power nanosecond optical parametric oscillator （OPO） have been numerically simulated. The OPO conversion efficiency is affected due to the angular deviation of real laser beams from ideal phase matching conditions. Our theoretical model is based on the decomposition of the Gaussian beam and assumes each component has a single deviation angle and thus a particular wave vector mismatch. We take into account the variable intensity profile in the spatial and temporal domains of the Gaussian beam, the pump depletion effects for large-signal processes as well as the oscillatory effects of the three waves. Two nonlinear crystals β-BaB2O4 （BBO） and LiB305 （LBO） have been investigated in detail. The results indicate that the degree of beam divergence strongly influences the maximum pump intensity, optimum crystal length and OPO conversion efficiency. The impact of beam divergence is much more severe in the case of critical phase-matching for BBO than in the case of non-critical phase-matching for LBO. The results provide a way to choose the optimum parameters for a high power ns OPO such as the nonlinear material, the crystal length and the pump intensity, etc. Good agreement is obtained with our experimental results.     

阶梯量子阱子带跃迁二次谐波产生的研究

本文理论上利用二能级近似下的传递矩阵法,给出了GaAs/Al_xGa_1-xAs二阶非线性光学系数X_2ω⁽²⁾的解析表达式,通过数值计算,设计了具有较大X_2ω⁽²⁾的阶梯多量子阱(SMQW)结构,其特点是单共振泵浦,实验上验证了该结构确实具有比体材料大3个量级的X_2ω⁽²⁾值,为了提高二次谐波(SHG)的转换效率,我们分别设计了两种新型的实验方案,分别使SHG转换效率较Brewster角入射下大10倍和100倍。     

激光分子束外延生长LaNiO_3薄膜最顶层原子平面的角分辨X-射线光电子谱研究

近几年来，钙钛矿型氧化物薄膜材料受到人们的很大重视．它的材料品种多，物理性能丰富，可以具有金属性、绝缘性、铁电性、铁磁性、超导性和光学非线性等多种特性．随着激光分子束外延技术的发展，薄膜领域出现了两个新的研究热点：氧化物晶体工程和氧化物电子学，为研制多功能大规模集成器件开辟了新的应用前景．LaNiO3晶体是重要的钙钛矿型氧化物材料之一，呈赝立方相结构，晶格常数a＝0．383nm，与许多其它钙钛矿型氧化物材料的晶格相匹配．同时，LaNIO3有优良的金属导电性，室温下的电阻率为0．225cm．因此，LaNiO3薄膜是氧化物铁…