20GHz注入锁模光纤激光器实验

稳定、波长可调谐的窄脉冲光源是未来光时分复用/波分复用光纤通信系统的重要组成部分。报道了一个20GHz的注入锁模光纤激光器的实验。利用一个10GHz的导体体激光器作为光源，最终得到了波长可调谐的重复频率为20GHz、脉冲宽度为12.4ps的光脉冲，波长的调谐范围为16nm。     

Researches of DC—Problem Under the Model S in which the Numbers of Defective Coins are not Fixed

In this paper,we research general Defective Cion Problem under the model S,i.e,the number d of Defective cions is not fixed. For d=O,1,or 2. we get some good results.     

HL－1装置中LHCD和等离子体参数的关系

本文研究了在ＨＬ－１托卡马克的不同放电阶段的低混杂波驱动特性。给出了驱动电流及驱动效率和等离子体参数，如电子平均密度ｎｅ、等离子体电流Ｉｐ及纵向磁场的关系。也给出和分析了波驱动和入射波功率的关系。在放电平段，对正反向驱动效率进行了研究和比较。     

高压下氢化锂晶体中的离子间力与结合能公式的原子分子设计

本文提出一种利用材料Hugoniot数据研究高压下离子晶体中微观离子状态及其离子间排斥作用势的新方法。对氢化锂晶体进行研究时,我们得到Li~+和H~-离子之间排斥作用势函数,结果表明文献〔1〕中提出的离子压缩效应具有客观性。     

Fixed Point Theorems on Product Topological Spaces and Applications

A new collectively fixed point theorem for a family of set-valued mappings defined on product spaces of non-compact topological spaces without linear structure is proved and some special cases are also discussed. As applications, some non-empty intersection theorems of sets with convex sections and equilibrium existence theorem of abstract economies are obtained under much weaker assumptions. Our results includes a number of known results as many special cases.     

Recognizing the P4-structure of a tree

The P₄-structure of a graphG =(V,E) is a hypergraphH = (V,F) such that, for every hyperedgeA inF, the cardinality ofA is four and the subgraph of G induced byA is a path. It is proved in this paper that the P₄-structure of a tree can be recognized in polynomial time.     

利用电泳技术在不锈钢和铁基底上制备MgB2带材

本文首次报道了利用电泳技术在铁和不锈钢基底上制备MgB2超导带材.电阻测量表明,沉积在铁和不锈钢基底上MgB2带材的超导零电阻转变温度分别为37.5K和31K,超导转变宽度分别为0.3K和1K.磁测量表明,(5K,OT)时不锈钢基底上带材的临界电流密度为6×105(A/cm2).X射线衍射谱和扫描电子显微镜图象表明样品结晶良好,晶粒生长致密.本工艺制备MgB2带材时不受系统真空度的限制,生长迅速,成本低廉,并且可以根据不同的需要任意选择基底的形状和大小.     

Low-threshold, high-efficiency, high-repetition-rate optical parametric generator based on periodically poled LiNbO3

We report a high-repetition-rate optical parametric generator (OPG) with a periodically poled lithium niobate (PPLN) crystal pumped by an acousto-optically Q-switched CW-diode-end-pumped Nd:YVO_4 laser. For the maximum 1064nm pump power of 970mW, the maximum conversion efficiency is 32.9% under the conditions of 250℃, 1064nm pulse repetition rate of 22.6kHz and pulse width of 12ns, and the PPLN OPG threshold in the collinear case is less than 23.7μJ. The output power increases with the increase of the crystal temperature. The 1485－1553nm signal wave and 3383－3754nm idler wave are obtained by changing the temperature and the angle of the PPLN crystal.     

Clustering study in Eu(DBM)3Phen-doped polymer optical fibers by optical properties and near-field scanning microscopy

The clusters of Eu3+ ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the 5D0 → 7F2 to 5D0 → 7F1 transitions with different concentrations of Eu3+ in Eu(DBM)3Phen-doped PMMA and metastable-state (5D0) lifetime dependence on Eu3+ concentration are analyzed. The analysis indicates that there are no clustering effects in Eu3+ ions of Eu(DBM)3Phen-doped PMMA when the Eu3+ doping concentration is up to 1.0 wt.-%. At the same time, the clustering effect has not been observed by the scanning near-field optical microscopy (SNOM) in Eu(DBM)3Phen-doped PMMA with 1.0 wt.-% of Eu3+ ions. The analysis reveals that a high concentration of Eu3+ can be incorporated into polymer optical fiber (POF) without clustering effect.OCIS codes: 180.5810, 300.6280, 250.5460, 160.5690.