用于光纤拉曼放大器抽运源的单级光纤拉曼激光器

抽运光源是光纤拉曼放大器应用于密集波分复用系统的关键技术,设计了一种紧凑型的808nm激光二极管抽运的基于钒酸钇（Nd^3＋：YVO4）晶体1342nm固体激光器模块,提出利用上述1342nm固体激光器抽运基于光纤光栅的单级全光纤型拉曼谐振器获得1．4μm激光输出的光纤拉曼激光器,分析了固体激光器的阈值特性、性能优化方法和单级光纤拉曼谐振器的设计方法。上述1342nm固体激光器模块在抽运功率2W时获得了最大655mW的激光输出功率和42．6％的斜率效率,单级拉曼谐振器的1342nm到1．4μm光功率转换斜率效率达75％,在1425nm、1438nm、1455nm和1490nm处的输出功率达到300mW以上。最后给出基于1．4μm光纤拉曼激光器抽运的宽带平坦放大的光纤拉曼放大器的结构参量和性能测试结果。     

弱Silnikov现象中的全局分支问题

本文考虑在一条同宿于具一对纯虚特征值的鞍－焦点的轨道邻域内的分支问题，证明了在同宿分支值的邻域内，存在着可数无穷多个鞍结点分支值，倍周期分支值和２－脉冲同宿分支值，并且两相邻鞍结点分支值的比趋于常数１。     

A Pricing Model for Optical Networks

Pricing of the optical networks will play a key role from network operator's point of view to achieve the maximum profit. This paper introduces pricing models for optical networks.     

POSITIVE SOLUTIONS FOR p-LAPLACIAN DYNAMIC EQUATIONS ON TIME SCALES

The three-point boundary value problems of p-Laplacian dynamic equations on time scales are investigated. By using Krasnosel＇skii＇s fixed-point theorem and fixed-point index theorem, criteria are achieved for the existence of at least one, two or 2n positive solutions. Furthermore, some examples are included to illustrate the main theorems.     

Bifurcations of heteroclinic loops

By generalizing the Floquet method from periodic systems to systems with exponential dichotomy, a local coordinate system is established in a neighborhood of the heteroclinic loop Γ to study the bifurcation problems of homoclinic and periodic orbits. Asymptotic expressions of the bifurcation surfaces and their relative positions are given. The results obtained in literature concerned with the 1-hom bifurcation surfaces are improved and extended to the nontransversal case. Existence regions of the 1-per orbits bifurcated from Γ are described, and the uniqueness and incoexistence of the 1-hom and 1-per orbit and the inexistence of the 2-hom and 2-per orbit are also obtained. Project supported by the National Natural Science Foundation of China (Grant No. 19771037) and the National Science Foundation of America # 9357622. This paper was completed when the first author was visiting Northwestern University.     

中国人CD59cDNA克隆、序列分析及其表达

用ＲＴ－ＰＣＲ方法从中国人胚胎总ｍＲＮＡ中扩增出４２０ｂｐ人补体终末阶段同源限制因子（ＣＤ５９）的ｃＤＮＡ，序列分析结果表明，所获得的ＣＤ５９ｃＤＮＡ与文献报道中的基因序列完全一致，含ＣＤ５９全长编码区．构建了真核表达质粒，在３Ｔ３细胞中得到了表达．     

Simultaneous wavelength conversion and pulse compression exploiting cascaded second-order nonlinear processes in LiNbO3 waveguides

Simultaneous wavelength conversion and pulse compression are proposed and demonstrated exploiting cascaded second-order nonlinear processes in periodically domain-inverted LiNbO₃ waveguides. The influences of initial pulse widths and waveguide length on the conversion efficiency and converted pulse compression are theoretically analyzed. Tunable wavelength conversion is performed for the signal pulse with the temporal width of 7.5 ps and repetition rate of 40 GHz. Conversion efficiency of more than −24 dB is obtained for 35-nm conversion span under average signal power of 10 dBm when a CW control wave is adopted.     

Mössbauer study of amorphous Fe40Ni40PxB20−x

The hyperfine field distributions of amorphous Fe₄₀Ni₄₀P_xB_20?x (x=10, 12, 14, 17) samples before and after different heat treatments have been determined by means of Mössbauer spectroscopy. All of these P(H) curves are characterized by a main high field maximum and an additional low field maximum, respectively. The asymmetry of distributions of high field component in P(H) of Fe₄₀Ni₄₀P_xB_20?x increases progressively from Fe₄₀Ni₄₀P₁₀B₁₀ to Fe₄₀Ni₄₀P₁₇B₃. The distributions of low field component in P(H) are affected differently by the annealing temperature. The results indicate that the phospoorus element plays an important role in the hyperfine interactions of amorphous Fe₄₀Ni₄₀P_xB_20?x The influence of annealing atmosphere has been discussed.     

BIFURCATION OF LIMIT LOOPS

The unified method is used to deal with the bifurcation problems of limit loops generated from the singular points of centre type and from the closed orbits. Some known results and methods are generalized and improved.