Nd~(3+)·YAG倍频激光纵向泵浦的可调谐染料振荡-放大激光器的研究

装置了一台由Nd~(3+)·YAG倍频激光纵向泵浦的可调谐染料激光器、该激光器由一双光栅系统的振荡器和一简单有效的放大器组成。用R6_g作染料,波长的可调范围是550nm——595nm。输出线宽是0.08Cm~(-1).放大系数为8～12。     

基于光纤光栅的可调谐光纤激光器

利用光纤光栅作为调谐装置研制了可调谐的光纤激光器 . 调谐装置简单, 性能稳定, 激光器输出波长在17 nm范围内连续可调, 输出功率大于1 mW,激光谱线线宽小于0.1 nm.     

外腔半导体激光器的实验研究

本文报道了外腔半导体激光器的一些研究成果。利用闪耀光栅作反馈元件，对808nm波长的半导体激光器形成弱耦合外腔，实现了光谱特笥较好的窄线宽单模激光输出，线宽小于0.06nm，边模抑制比大于30dB，最大输出功率为35.4mW，总的光－光转换效率为46％。通过调整光栅转角，可以得到11.66nm的波长调谐范围。设计了光栅－反向镜联动结构，使外腔半导体激光器的输出方向不再随调谐而变化。     

一种双频共激活区调谐的染料激光放大系统

用双频染料激光的相关调谐原理，设计了一种不用分束耦合元件的新型迈尔克逊双频选频腔，实验实现了共线，宽调谐范围，功率比可控，可调，窄线宽的双频激光的振汇与放大，获得了脉冲能量12－13mJ的高功率输出。     

一种输出稳定的窄线宽可调谐掺铒光纤激光器

用薄膜滤波器作为调谐元件,在激光器谐振腔内加入一段未泵浦的掺铒光纤,利用其空间烧孔效应压窄线宽和稳定输出,设计了一种输出稳定的可调谐窄线宽掺铒光纤激光器.调谐范围为1 530～1560nm,输出线宽小于0.06 nm,输出稳定,受振动等环境因素影响小.     

N_2激光泵浦的可调谐染料激光器

本文叙述了染料激光器的基本原理和一台用N_2激光泵浦的可调谐染料激光器的实验装置,该装置提供了5450～6300A的光谱调谐范围,6A的激光线宽;并讨论了染料溶液的浓度和pH值对发射激光波长的影响。     

可调谐掺铒光纤环形腔单纵模激光器

利用驻波干涉和饱和吸收诱发的自写入光纤光栅的窄带滤波特性及反射波长自适应特性,通过内置可调谐介质薄膜滤波器研制成了可调谐掺铒光纤环形腔单纵模激光器。其有效可调谐波长范围达33nm,在波长连续调谐范围之内均为单纵模输出,激光线宽稳定在2.35KHz以下。     

高功率可调谐超短激光脉冲

用高重复频率的准分子(Xecl)激光器泵浦染料可调谐激光器的腔倒空输出,进行二级超短脉冲放大。染料可调谐激光器是由锁模氩离子激光器泵浦,得到了峰值功率为8.5Mw,脉冲重复频率100Hz,波长从5780(?)到6150(?)可连续调谐,脉宽为微微秒的激光输出。     

一种环型腔可调谐掺铒光纤激光器的研究

利用光纤光栅作为调谐装置研制了可调谐的光纤激光器.调谐装置简单,性能稳定,实验中选定激光二极管工作电流为300 mA,激光输出功率为6.747 mW的条件下,实现激光输出波长在1 546.326 0 nm到1 549.736 0 nm范围内连续可调.     

846 nm半导体激光器线宽压窄的研究

研制了用于倍频蓝光的单模、可调谐的窄线宽光栅外腔反馈半导体激光器,它是由激光器底座、激光管组件、准直透镜组件和光栅组成.经过精密控制电流和温度,利用光栅反馈可获得激光单纵模输出,外腔的结构还使输出光的谱线宽度得以压窄.对研制的半导体激光器的特性测试表明,其输出功率稳定,阈值变小,模式单一稳定,波长可调谐,谱线宽度小于1 MHz.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the