非临界相位匹配KTP光学参量振荡器的研究

利用1.06μm激光脉冲泵浦非临界相位匹配（NCPM）KTP光学参量振荡器,获得中心波长1566nm的信号光输出。信号光脉冲宽度比泵浦光脉冲宽度小得多,当光学参量振荡器的腔长分别为3cm、6cm和8cm时,得到的信号光脉冲的时间宽度分别为6ns、4ns和3ns,并从理论上加以解释。     

基于PPLT晶体的瓦级中红外光参量振荡器研究

采用脉冲电场畴反转技术制备了长40mm、厚1mm、周期为28.6μm的钽酸锂超晶格（PPLT）晶体。利用工作波长在1.064μm的Nd：YAG激光器作为抽运光源,未镀膜的PPLT晶体作为非线性工作介质,实现了一台输出信号光波长在1.48gm、闲频光波长在3.8gm的光参量振荡器.在抽运功率为20w,调Q频率为5.1KHz时得到3W的信号光功率输出,中红外光功率大于1.2W,波长调谐范围超过200nm。进一步优化光参量振荡器元件参数,红外激光输出功率还能有较大提高。     

PPLN准相位匹配内腔光学参量振荡器的实验研究

将准相位匹配光学参量振荡器(QPM-OPO)置于激光二极管(LD)端面泵浦的声光调Q1064nm-Nd:YVO4激光器谐振腔之内,获得了信号光单谐振的内腔光参量输出。在声光Q开关重复频率为25kHz的条件下,内腔参量振荡的阈值仅为0.9W(LD功率)。在6WLD泵浦功率下,获得了350mW的信号光输出。通过在120℃~250℃范围内改变PPLN晶体的温度,信号光输出实现了在(1493~1538)nm波段的调谐。     

基于MgO掺杂LiNbO_3的高功率2μm光参量振荡器

采用1μm激光泵浦周期性极化掺镁铌酸锂晶体光参量振荡器(Mg O:PPLN OPO),实现了高功率2μm近红外激光输出.利用Nd:YVO_4激光器产生的1μm激光泵浦Mg O:PPLN OPO,在泵浦功率为7.2 W时,获得了5.3 W的2μm激光输出,转换效率为74%.泵浦源改用Nd:YAG激光器,并对其进行优化设计,提高了Nd:YAG激光器的输出功率和光束质量,用其泵浦MgO:PPLN OPO,在泵浦功率为25 W时,获得了9.5 W的2μm激光输出.     

1053nm同步抽运飞秒光参量振荡器

报道了基于PPLN晶体的同步抽运的飞秒光参量振荡器．抽运源为一台自制的重复频率为80MHz的钛宝石振荡器,在满足同步抽运的条件下,通过腔长调谐得到了波长从1000-1200nm连续可调的信号光．当调谐至1053nm时,信号光的功率为32mW,光谱宽度为13nm,脉冲宽度为342fs．另外,在调谐过程中观察到了双波长现象．     

1.5μm连续内腔单共振光学参量振荡器运转特性的实验研究

通过内腔单共振光学参量振荡器(SRO),获得了连续单频的1.5μm激光光源.实验采用PPLN晶体为非线性晶体,通过优化设计Nd:YVO4激光器的参数和SRO腔的参数,在LD泵浦功率为18W时,获得了300mW的连续单频1.5μm激光输出.实验与理论相结合,详细分析了SRO的运转特性,并提出了进一步优化SRO的方法.     

我省已公布的专利简介(四)

实用新型名称:一种连续改变激光脉冲频率的电源分类号:HO1S3/10GG85201364这是一种连续改变激光脉冲频率的电源。它用连续可调振荡器和可变信频器来替代脉冲激光器中的固有频率振荡器,并由连续可调振荡器控制电光调制器来调制脉冲激光器,从而得到频率连续可调的激光脉冲。     

利用飞秒光梳获得正交压缩态

介绍了利用周期性极化KTP晶体的参量下转换过程制备飞秒光场压缩态的实验研究.实验使用运转于阈值以下的同步泵浦光学参量振荡器获得了压缩度为2.9dB、中心波长为795nm、重复频率为76 MHz的飞秒正交振幅压缩态光场.考虑到系统传输测量过程中的损耗,实际输出压缩度应该为3.8dB.     

中红外光参量产生器的寄生振荡问题

寄生振荡是影响光学参量产生器的转换效率、参量光输出稳定性以及参量光光束质量的关键因素．而且随光斑分布和非线性效应,寄生振荡现象很难消除．文章重点对比了中红外光参量振荡器和光参量放大器两种不同器件中的寄生振荡问题,以及其对器件输出功率和输出激光光束质量的影响．研究表明：在PPMgLN晶体中,高阶准相位匹配是产生寄生振荡的重要原因．     

基于周期极化铌酸锂的可调谐内腔光参量产生的实验研究

实现了基于周期极化铌酸锂的人眼安全波段全固态可调谐高重复频率内腔光学参量产生过程,得到了1．6w的二极管泵浦阚值,最大输出信号光功率为330mW,并在（1．497～1．517）um范围波长可调。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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