Design of Broadband L-band Erbium Doped Fiber Amplifier

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｗａｖｅｌｅｎｇｔｈ ｄｉｖｉｓｉｏｎｍｕｌｔｉｐｌｅｘｉｎｇ(ＷＤＭ )ｍｅｔｈｏｄｇｉｖｅｓａｓｏｌｕｔｉｏｎｏｆｄｅｍａｎｄｏｎｔｈｅｈｉｇｈｓｐｅｅｄａｎｄｈｉｇｈｃａｐａｃｉｔｙｔｒａｎｓｍｉｓｓｉｏｎ .ＯｎｅｏｆｔｈｅｋｅｙｔｅｃｈｎｏｌｏｇｙｏｆｔｈｅＷＤＭｔｒａｎｓｍｉｓｓｉｏｎｉｓｔｏｂｒｏａｄｅｎｂａｎｄｗｉｄｔｈｏｆｅｒｂｉｕｍ ｄｏｐｅｄｆｉｂｅｒａｍｐｌｉｆｉｅｒ (ＥＤＦＡ)ａｎｄｔｏｇｅｔｔｈｅｗｉｄｅｂａｎｄａｎｄｆｌａｔ ｇａｉｎＥＤＦＡ .…     

低泵浦功率的遥泵放大在超长跨距密集波分复用系统中的应用

针对长跨距密集波分复用系统中喇曼放大入纤泵浦功率过大的问题，将遥泵放大器（RP-EDFA）引入到系统中，通过对共纤RP-EDFA的噪音性能及其优化设计的研究，在理论上计算比较了RP-EDFA系统和后向喇曼放大系统在不同泵浦功率水平下的光信噪比和非线性相移，表明遥泵放大技术有效降低了入纤泵浦的功率水平，更适合长跨距应用.运用遥泵放大技术，对一个典型的长跨距系统进行系统Q值的模拟，结果表明：在 220 mW泵浦功率水平下可以实现跨距为 167 km的40×11.6 Gbit/s系统1000 km传输，Q值裕量4.4 dB.     

直接序列扩频系统中数字Costas环的设计与实现

主要针对直接序列扩频系统(DSSSS)的载波同步,研究了数字Costas环的设计和实现方法.介绍了数字Costas环的结构和其提取载波频率和相位、实现载波同步的基本原理.以典型的二阶连续系统的离散数字化方法为基础,分析了线性数字锁相环(DPLL)的参数设计方法,为非线性的数字Costas环的设计提供了参考.提出了一种在高速数字信号处理器(DSP)中数字Costas环的软件实现方案;经过试验验证,能够实现载波同步,并且应用更加简单、灵活,性能更加稳定.     

Asymmetric cycloaddition of β,γ-unsaturated α-ketoesters with electron-rich alkenes catalyzed by a chiral Er(OTf)3/N,N'-dioxide complex: highly enantioselective synthesis of 3,4-dihydro-2H-pyrans

The asymmetric inverse-electron-demand hetero-Diels-Alder (HDA) reactions of β,γ-unsaturated α-ketoesters with electron-rich alkenes were investigated, with an N,N'-dioxide/erbium(III) complex employed as the catalyst. Quantitative conversion of the β,γ-unsaturated α-ketoesters and excellent enantioselectivities (up to >99% ee) and diastereoselectivities (up to >99:1 d.r.) were observed for a broad range of substrates by using a 0.5-0.05 mol% catalyst loading under mild reaction conditions. The reaction could be scaled up to the gram scale with the same results. In addition, this was the first application of Er(OTf)(3) to the asymmetric inverse-electron-demand HDA reaction and it behaved as an efficient catalyst. Moreover, the synthetic utility of this methodology was demonstrated with the synthesis of key intermediates of some natural products.     

单模光纤陀螺正交锁相检测方法的研究

研究了用于干涉型单模光纤陀螺系统的正交锁相检测方法，采用双参考信号，使输出的信号与噪声分离，不仅提高了光学系统信号的信噪比，同时可以引入移相反馈控制，大大减小了系统的漂移，系统的零点漂移已达到０．２ｄｅｇ／ｈ。     

All-Fiber Optical Add-Drop Multiplexer Using a Pair of Fiber Grating Couplers

A new all-fiber optical add-drop multiplexer (ADM) using a pair of fiber grating couplers (FGCs) was proposed and first demonstrated. It was theoretically and experimentally shown that both drop and add efficiencies could be maximized in the proposed ADM. It was also clarified that the crosstalk between dropped and added signals could be improved in the proposed ADM compared with that in the single FGC. Drop and add operations in the ADM for 3-channel WDM signals with 1.6 nm wavelength spacing were confirmed. The ADM with signal amplification ability, which consists of a pair of FGCs, an EDF, and a pump-LD, was proposed and demonstrated. It was confirmed that the dropped and transmitted optical signals could be amplified in the ADM, and would be able to expand fiber routing spans.     

增益介质的色散对锁模激光器输出脉宽和啁啾的影响

利用时间域内各光学元件的传播矩阵,在考虑了增益介质的色散后,对锁模激光器输出的脉宽和啁啾做了理论方面的推导,并做了相关的数值模拟,结果表明:当不考虑增益介质的色散时,其输出脉宽啁啾值为零;而考虑了增益介质的色散后,啁啾值随色散值的增加先增加而后降低,且存在一个最大值,脉宽随色散值的增加而增加.     

利用啁啾光纤光栅色散特性实现波长可调谐的主动锁模掺铒光纤环行腔激光器

在环形腔主动锁模光纤激光器中引入啁啾光纤光栅，利用啁啾光纤光栅的大色散特性，通过调节调制频率，实现波长调谐，调谐范围2nm。所得脉冲为重复频率2．5GHz，脉宽约60ps的正啁啾脉冲，。     

Crystallographic report: Crystal structure of tris(2,6‐di‐tert‐butyl‐4‐methylphenolato‐O) (tetrahydrofuran‐O) erbium toluene solvate

A low‐coordinate aryloxo erbium complex, [(ArO)₃Er(THF)](MePh), has been synthesized by the reaction of anhydrous ErCl₃ with three equivalents of NaOAr in tetrahydrofuran. The central erbium atom is coordinated by three oxygen atoms of the aryloxo ligands and one oxygen atom of the tetrahydrofuran molecule, resulting in a distorted tetrahedron. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and Structure of Di－μ－chlorobis（di－tert－butylcyclopentadienyl） Erbium Chloride

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