非线性光学晶体LBO位相匹配高功率绿光激光器

目的 对非线性光学晶体LBO的倍频属性以及影响倍频效率的各种因素进行理论分析与实验研究。方法 光与物质相互作用的耦合波方程和非线性光学晶体倍频时满足的相位匹配条件。结果 在激光二极管双端泵浦Nd：YVO4腔内倍频绿光激光器的实验中，对于两种不同匹配方式倍频的LBO晶体的倍频特性进行了研究。采用I-类角度位相匹配晶体倍频时，抽运光功率约为26W时，获得了最大输出为4．2W的稳定基模绿光，光．光转换效率达到18％；采用I-类非临界位相匹配晶体倍频时，抽运光功率约为28．9W时，获得了8W稳定的基模绿光输出，光．光转换效率达到31％。结论 通过对于LBO晶体倍频特性的理论分析与实验研究，使Nd：YVO4／LBO激光器获得了较高的输出功率和具有较高的转换效率。     

LD端面泵浦激光晶体热效应分析

针对二极管激光器端面泵浦Nd:YVO晶体工作特点,提出矩形各向异性激光晶体热模型.在晶体周边冷却,两通光面绝热情况下,通过求解泊松热传导方程,得出了矩形截面Nd:YVO4激光晶体的温度分布,进而求解Nd:YVO4激光晶体端面热膨胀量.研究结果表明,在泵浦功率为18W时,激光晶体泵浦面最高升温344.4K,最大热形变量2.85μm.对激光晶体温度场分布和端面热形变的研究,为解决晶体热效应提供了理论基础.     

激光二极管端面泵浦Nd:YVO4/YVO4复合晶体激光器热效应研究

针对Nd:YVO4/YVO4复合晶体热传导的实际特点,提出了三维各向异性热传导模型,计算出晶体中的温度场分布.定量分析了LD端面泵浦条件下激光晶体的长度及折射率与温度变化的关系,得到晶体在不同泵浦功率下的热焦距.在此基础上,采用三镜折叠腔,设计出高转换效率KTP腔内倍频连续绿光激光器.当泵浦功率17W时,得到9.33W 1064nm和5.01W 532nm的激光输出,最高光-光转换效率分别为59.1%,34.4%.理论计算及实验结果表明复合晶体能很好地消除热透镜效应,在制造高效稳定的大功率固体激光器中具有重要应用价值.     

连续输出1.60 W/473 nm直腔蓝光激光器

报道了LD端面泵浦Nd：YAG晶体，LBO腔内倍频473nm全固态直腔蓝光激光器．根据谐振腔稳定性理论，利用简单的平-平腔直接测得不同泵浦功率下的热焦距值．通过数值计算分析了不同热焦距下，Nd：YAG与LBO晶体中的腰斑半径以及LBO中光腰的位置。并在准三能级系统模型和倍频理论的指导下优化激光腔体结构，使激光器实现最佳的模式匹配和倍频效率，得到高效的蓝光激光输出．激光阈值为1．92W；当泵浦激光功率为20．58W时，473nm蓝光的输出功率为1．60W。光-光转化效率为7．8％．     

LD端泵Nd:YVO4固体激光器输出特性的实验研究

在不同腔反馈、晶体尺寸和掺杂浓度情况下，对LD端面泵浦平直腔Nd：YVO4固体激光器进行了实验研究．测量了晶体的热透镜焦距，在泵光功率21W时，实现了稳定的8．5W准基模输出，光-光转换效率40．5％，斜效率达到59．4％．     

激光二极管端面泵浦Nd:YVO4板条激光器

利用激光二极管列阵端面泵浦Nd:YVO4板条激光晶体结合稳定-非稳混合腔结构,获得78.9W近衍射极限1064nm 激光输出,斜效率52.4%,光-光转化效率42.9%.     

LD抽运Nd∶YAG复合腔双波长激光器

研究激光二极管(LD)端面抽运的Nd∶YAG三镜复合腔激光器的1 064,946 nm双波长激光连续运转.在满足双波长激光振荡阈值相等的条件下,考虑Nd∶YAG晶体的热透镜效应,数值计算1 064,946 nm两个子腔的腔长、输出镜透过率之间的关系.结果表明,当Nd∶YAG晶体中抽运光,1 064,946 nm激光的光束半径达到合理匹配时,两个子腔的输出镜透过率之间有确定的关系.选取合适的复合腔结构参数,当抽运功率为9 W时,可同时获得1.1 W的1 064 nm激光,以及500 mW的946 nm激光输出.     

LD抽运Nd:YVO_4双波长激光器的输出特性

在满足双波长激光振荡阈值相等的条件下,分析和数值计算抽运光、双波长(1.34,1.06 μm)振荡激光光束半径的相对大小,以及其对两个子腔输出镜透过率关系的影响.研究发现,当抽运光、两种波长激光的光束半径之比达到一定值时,两个子腔输出镜透过率之间的最佳关系不随腔内光束半径的变化而变化在考虑Nd∶YVO4晶体的热透镜效应情况下,可合理地选择2个子腔腔长来实现双波长(1.34,1.06 μm)激光相同的振荡阈值.实验结果表明,抽运功率较小(小于11 W)时,输出的1.06 μm激光功率大于1.34 μm激光功率;抽运功率较大时(大于11 W),1.34 μm激光功率超过1.06 μm激光功率;当抽运功率等于11 W时,1.34 μm和1.06 μm激光功率均为0.675 W.     

LD泵浦双棒串接Nd:YVO4激光器的研究

目的 研制一种光纤耦合LD双端泵浦双棒串接Nd：YVO4平平腔全固态近红外激光器。方法用软件进行设计。结果 在抽运功率为23．05W时获得了11W的1．06μm TEM00模激光输出，光一光转化效率为47．72％。另外，对不同掺杂浓度下的实验结果及腔的稳定性进行了一些探讨。结论 提高晶体的掺杂浓度和选择适当的输出耦合系数可以得到更好的结果。     

半导体激光器端面泵浦高功率高效Nd:YVO4/KTP腔内倍频连续绿光激光器研究

报道一种由三镜折叠腔构成、半导体激光器端面泵浦低阈值高功率高效Nd∶YVO4/KTP腔内倍频连续绿光激光器 .在泵浦功率为 1 9W时 ,TEM0 0 模绿光输出功率为 5 85W ,相应的光 -光转换效率为 3 0 8% .实验结果证实了Nd∶YVO4晶体的温度对于KTP晶体的容许温度范围有很大影响 .     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has