加长棒脉冲钕玻璃激光器异常实验现象理论研究

以激光原理为基础, 以大量精确的实验数据为依据;考虑被忽略的自发辐射的影响, 对加长到抽运腔外的钕玻璃棒, 未受到抽运, 反而产生光放大异常实验现象的机理进行了理论研究.理论研究结果与实验结果基本相符.     

无粒子数反转激光研究的进展

概括地介绍了无粒子数反转光放大与无粒子数反转激光的基本概念和原理，讨论了这种类型激光对激光科学发展的重要意义，叙述了自１９６２年以来科学家们所提出的几种实现无粒子数反转光放大及无粒子数反转激光的主要的理论模型和有关的实验进展，最后介绍了钠原子蒸汽中首次观察到无粒子数反转光放大的实验装置和实验结果。     

EDFA黑盒模型及其虚拟实验验证

首先根据EDFA两能级放大模型推导出黑盒模型;其次,采用虚拟实验方法,分析了黑盒模型在不同条件下计算的精度;最后分别模拟放大系统采用黑盒模型和两能级模型,有八个WDM光信号输入时,放大后的光谱图.结果表明两者十分一致.     

光的力学效应及光阱力的测量

介绍一个利用光镊技术直观地演示光的力学效应的实验。简要讨论了开设这一实验的背景和目的，给出了光镊原理、实验装置、光阱力的测量方法和实验安排。     

高锦岳等人首次做出无粒子数反转放大实验

 世界各国科学家探索20多年的一项科学实验--无粒子数反转条件下的光放大,在吉林大学物理系实验成功,并于去年通过了由国家自然科学基金委员会主持的专家评议.这项实验是由吉林大学物理系高锦岳教授主持的科研小组,经过三年多的努力获得的.在国家自然科学基金委员会主持的专家评议会上,专家们认为,由吉林大学物理系高锦岳教授主持的课题组研究的无粒子数反转光放大实验是成功的,是激光物理和量子光学中的开创性实验,是激光物理基础理论的重大突破,在世界上尚属首次.     

掺铒光纤激光放大的实验研究

使用自行研制的掺铒光纤维进行了光纤激光放大实验.以Ar~+激光作泵浦,在1.52 μm波长上实现了光放大,增益达10dB以上.绘出了有关掺铒光纤及其光放大的若干实验数据.     

基于光放大的光纤Fizeau应变传感器频分复用系统

提出了一种可频分复用基于光放大的光纤Fizeau应变传感器的方法，从原理上解决了现有光纤Fabry-Perot传感器固有的两大弱点：信号弱和复用难.利用掺铒光纤的放大作用，既形成宽带光源，又放大了微弱的信号.描述了该应变传感器系统的结构、原理及实验结果.实验表明该复用传感器应变测量精度可达±10με，可满足实际应用的要求. 关键词： 光纤传感器 光纤应变传感器 掺铒光纤 复用     

宽带光参量放大过程中的转换效率提升

建立了宽带光参量放大数值模拟平台,并基于此对宽带光参量放大系统的能量转换效率提升进行优化设计,根据模拟计算结果可以对实验中能够达到的最优化能量转换效率进行预判。建立了验证实验平台并进行了实验,研究并攻克了实验中遇到的参量荧光抑制、信号光,泵浦光空间精确匹配、脉宽精确匹配、时间波形整形等关键技术难点。在抑制参量荧光的同时实现了宽带光参量放大过程能量转换效率的提升,在单级宽带光参量放大过程中获得了30%的能量转换效率。     

高效三通光参量啁啾脉冲放大器

为了提高信号光与抽运光在时域上的匹配,提高放大系统的增益,提出了三通光参量啁啾脉冲放大的方法。实验中,信号光在一块晶体内被一抽运光在完全相位匹配的条件下放大了三次,总放大增益为3.7×107,能量晃动小于3%rms,放大后的信号光谱宽为30nm,压缩后的信号光脉宽为82fs。实验结果表明:采用三通光参量啁啾脉冲放大方法,有效地抑制了放大过程中参量荧光对放大过程的影响,在抽运光强为350MW/cm2时,参量荧光仅占输出总能量的1%。     

高质量高效率高稳定性参量放大光产生的研究

针对光参量放大实验中存在的参量转换效率低、输出光脉冲形状畸变和输出稳定性差等问题进行了详细研究，对注入信号光强、抽运光耗尽、增益饱和、和频过程等因素对参量过程的影响进行了详细分析讨论，并进行了光学参量放大的实验研究.理论和实验研究结果表明通过优化选择合适的注入信号光强、抽运光强和晶体长度等参数，使参量放大运行在深度增益饱和状态的稳定区，完全可以获得高质量高效率高稳定性的参量放大输出光. 关键词： 光参量放大 抽运光耗尽 增益饱和 稳定性     

Ruby Crystal for Demonstrating Time- and Frequency-Domain Methods of Fluorescence Lifetime Measurements

We present experiments that are convenient and educational for measuring fluorescence lifetimes with both time- and frequency-domain methods. The sample is ruby crystal, which has a lifetime of about 3.5 milliseconds, and is easy to use as a class-room demonstration. The experiments and methods of data analysis are used in the lab section of a class on optical spectroscopy, where we go through the theory and applications of fluorescence. Because the fluorescence decay time of ruby is in the millisecond region, the instrumentation for this experiment can be constructed easily and inexpensively compared to the nanosecond-resolved instrumentation required for most fluorescent compounds, which have nanosecond fluorescence lifetimes. The methods are applicable to other luminescent compounds with decay constants from microseconds and longer, such as transition metal and lanthanide complexes and phosphorescent samples. The experiments, which clearly demonstrate the theory and methods of measuring temporally resolved fluorescence, are instructive and demonstrate what the students have learned in the lectures without the distraction of highly sophisticated instrumentation.     

INFRARED AND RAMAN SPECTROSCOPY IN PAPER AND PULP ANALYSIS

Infrared and Raman spectroscopy are essential analytical tools for the structural analysis of paper and pulp chemistry. The studies of cellulose, hemicellulose, lignin, thermal- and photo-induced oxidation; cross-linking; and various chemical treatments of pulp and paper products are all made possible using these forms of molecular spectroscopy. In this review, containing 70 references, a broad range of applications into pulp and paper materials, components, and processes is described from recent and classic research over predominantly the past 20 years.     

基于THz-TDS技术的培氟沙星和氟罗沙星抗生素定性定量检测研究

作为两种常用的喹诺酮类抗生素,培氟沙星和氟罗沙星残留问题引起人们的高度关注,研发快速、高效的检测手段成为一种需求。采用太赫兹时域光谱(THz-TDS)技术对鱼粉基质中的培氟沙星、氟罗沙星进行了研究。制备培氟沙星、氟罗沙星、聚乙烯和鱼粉纯净物质以及培氟沙星-鱼粉和氟罗沙星-鱼粉17种不同浓度二元混合物的压片样品,共106个;对所有压片样品进行太赫兹光谱测量和分析;利用连续投影算法(SPA)结合支持向量机(SVM)和反向传播神经网络(BPNN)建立定性判别模型,对培氟沙星-鱼粉和氟罗沙星-鱼粉这两种混合物进行分类判别;利用特征频率处吸收系数建立偏最小二乘回归(PLSR)、BPNN、多元线性回归(MLR)定量预测模型,分别对两种混合物进行定量预测。结果表明：纯净培氟沙星在0.775和0.988 THz存在明显吸收峰,纯净氟罗沙星在0.919和1.088 THz存在明显吸收峰,聚乙烯对太赫兹波基本没有吸收,鱼粉无吸收峰,两种抗生素与鱼粉混合后的峰值出现在纯净抗生素的吸收峰附近;在定性判别中,SVM判别结果最佳,预测集判别准确率、精确率、召回率、F1得分分别为97.06%,97.22%,97.06%和97.06%;定量回归中,SPA-BPNN 模型用于预测培氟沙星-鱼粉结果最佳,预测集相关系数(R_p)、预测集均方根误差(RMSEP)分别为0.984 9和0.009 5,SPA-MLR模型用于预测氟罗沙星-鱼粉结果最佳,R_p和RMSEP分别为0.982 7和0.040 6。研究表明THz-TDS技术对鱼粉基质中培氟沙星、氟罗沙星进行定性定量检测是可行的,为畜禽行业中培氟沙星和氟罗沙星实际检测提供理论和技术参考。     

Process Physics: Inertia, Gravity and the Quantum

Process Physics models reality as self-organising relational or semantic information using a self-referentially limited neural network model. This generalises the traditional non-process syntactical modelling of reality by taking account of the limitations and characteristics of self-referential syntactical information systems, discovered by Gödel and Chaitin, and the analogies with the standard quantum formalism and its limitations. In process physics space and quantum physics are emergent and unified, and time is a distinct non-geometric process. Quantum phenomena are caused by fractal topologicaldefects embedded in and forming a growing three-dimensional fractal process-space. Various features of the emergent physics are briefly discussed including:quantum gravity, quantum field theory, limited causality and the Born quantum measurement metarule, inertia, time-dilation effects, gravity and the equivalence principle, a growing universe with a cosmological constant, black holes and event horizons, and the emergence of classicality.     

Stabilization of biosolids with nanoscale zero-valent iron (nZVI)

Biosolids are the treated organic residuals, also known as sludge, that are generated from domestic wastewater treatment plants. According to the USEPA, over 7 millions tons (dry weight) of biosolids are generated every year in the US by more than the 16,000 wastewater treatment plants and a large portion of these biosolids is disposed on land. Nuisance odors, the potential of pathogen transmission, and presence of toxic and persistent organic chemicals and metals in biosolids have for the most part limited the use of land applications. This paper presents zero-valent iron nanoparticles (1–100 nm) for the treatment and stabilization of biosolids. Iron nanoparticles have been shown to form stable and nonvolatile surface complexes with malodorous sulfur compounds such as hydrogen sulfide and methyl sulfides, degrade persistent organic pollutants such as PCBs and chlorinated pesticides, and sequestrate toxic metal ions such as mercury and lead. The end products from the nanoparticle reactions are iron oxides and oxyhydroxides, similar to the ubiquitous iron minerals in the environment. Due to the large surface area and high surface reactivity, only a relatively low dose (<0.1% wt) of iron nanoparticles is needed for effective biosolids stabilization. The iron nanoparticle technology may thus offer an economically and environmentally sustainable and unique solution to one of the most vexing environmental problems.     

高光谱成像技术在果蔬品质与安全无损检测中的原理及应用

水果和蔬菜的品质与安全是消费者最为关心的问题。传统的化学检测方法是一种费时费力的破坏性检测技术。随着成像和光谱技术的快速发展,高光谱成像技术已经广泛应用于农产品品质与安全的快速无损检测中。高光谱成像技术融合了传统的成像和光谱技术的优点,可以同时获取被检测物体的空间信息和光谱信息,因此该技术既可以像检测物体的外部品质,又可以像光谱技术一样检测物体的内部品质和品质安全。目前,已经有大量的基于高光谱成像技术检测水果和蔬菜品质与安全的研究性论文发表,为了深入了解高光谱成像技术的检测原理并跟踪国内外最新的研究进展,综述了高光谱成像技术在水果和蔬菜外部品质、内部品质和品质安全检测中的原理、发展和应用。另外,还简要介绍和讨论了高光谱成像系统的构成、常用的数据分析方法、发展趋势及面临的挑战。     

Stability of elliptic vortex solitons in anisotropic nonlocal media

Elliptic vortex solitons are investigated in anisotropic nonlocal media with more general formulations. We address the existence and dynamics of such solitons analytically and numerically. The solution of elliptic vortex solitons depends on the eccentricity of both the input beam and nonlocal response function. With different degrees of nonlocality, we numerically investigate the evolution of the elliptic vortex solitons, and find that, typically, the elliptic vortex solitons with single and double charges collapse into spiraling dipole- and tripolelike soliton clusters, respectively.     

Influences of laser in low power YAG laser-MAG hybrid welding process

The influences of laser defocusing amount △z, laser power P, space distance DLA between laser and arc on weld penetration, arc modality and stability are investigated in low power YAG laser and metal active gas （laser-MAG） hybrid welding process. The experimental results indicate that the effects of laser-induced attraction and contraction of MAG arc are emerged in hybrid welding process, which result in the augmentation of hybrid welding energy. When DLA ： -0.5 - 2 mm, △z = -2 - 2 mm and P ≥ 73 W, the synergic efficiency between laser and MAG arc is obvious, the cross section at the root of hybrid arc is contracted and the hybrid weld penetration is increased. The maximal ratio of hybrid/MAG weld penetration is 1.5 and the lowest YAG laser power that augments MAG arc is 73 W. The input of YAG laser makes the stabilities of arc ignition and combustion prominent in hybrid welding process.     

Hydrogen for novel materials and devices

We start by recalling some of the properties of hydrogen and present a summary of the phenomena caused by the reversible hydrogen sorption by metals and various forms of condensed carbon, at the surface and into the bulk, using molecular hydrogen gas, hydrogen plasma and electrochemically sorbed hydrogen. We then describe the use of hydrogen to modify the surface and bulk properties of various materials with a focus on applications and devices: electronic and optic phase transitions of thin films and related energy devices, surface polishing and cleaning, decrepitation and amorphization of intermetallics, growth of carbon nanostructures and electron emission from diamond-like and graphitic carbon, longrange perturbation of the electron distribution of graphitic structures by hydrogen defects, and the consequences for potential nanoelectronics. Received: 8 November 2000 / Accepted: 20 November 2000 / Published online: 9 February 2001     

Time domain finite volume method for the transient response and natural characteristics of structural-acoustic coupling in an enclosed cavity

A time domain finite volume method（TDFVM）based on wave theory is developed to analyze the transient response and natural characteristics of structural-acoustic coupling problems in an enclosed cavity.In the present method,the elastic dynamic equations and acoustic equation in heterogeneous medium are solved in solid domains and fluid domains respectively.The structural-acoustic coupling is implemented according to the continuity condition of the particle velocity along the normal direction and the normal traction equilibrium condition on the interface.Several numerical examples are presented to validate the effectiveness and accuracy of the present TDFVM.Then the effects of water depth on the acoustic and vibration characteristics and the natural characteristics of a structural-acoustic coupling system are analyzed.The numerical results show that the increase of water depth leads to a stronger coupling between the water and structure and the decrease of natural frequencies of coupling system,The computational cost and memory of this method are small and it can be applicable to structural-acoustic coupling problems in the heterogeneous fluid.