【作者】 闫红伟；

【导师】 郭玉彬；

【作者基本信息】 吉林大学 ， 通信与信息系统， 2007， 硕士

【摘要】 随着密集波分夊用( DWDM )技术的上断发展，系统传输容量日益增大。通过与传统C波段掺铒光纤放大器(E DFA )相结合，L波段EDF A能显著的拓展原有的增益带宽，提高系统的信道容量，因此L波段EDF A已逐渐成为新一代DW DM系统的关键器件，它的可实现性决定着宽带DWD M系统能否实现以及其性能的优劣。本文提出了两种上同腔形的L波段掺铒光纤放大器研究方案。通过在信号的输入(线形腔)或输出端(环形腔)引入单根光纤布拉格光栅( FBG )，将部分背向或正向C波段放大自发辐射(A S E)反射入回路中，获得了较好的增益钳制效果和噪声性能。线形腔L-b and EDF A采用两段ED F结构，采用148 0nm LD作为泵浦源以提高泵浦吸收率。当泵浦功率为1 80m W，输入15 89 nm信号光，功率从- 30d Bm变化到- 8dB m时，增益被钳制在23 dB，且噪声指数(N F)低于5dB。由于通过FB G将部分背向A SE反射入EDF，输入小信号增益提高了5dB。15 89nm处的饱和输出功率达到7dBm，在1614 nm处获得了1 6 dB的高增益。同时，进行了环形激光腔结构的L-b an d E DFA实验研究。当泵浦功率为1 80m W，输入1 589 nm信号光，功率从- 30d Bm变化到-1 2dB m时，增益被钳制在1 7.5d B，增益起伏小于0 .3d B，且N F低于5 dB。调整腔内损耗，输入小信号增益最大达到1 9.7 8dB。在15 89 nm处获得高达8.5 dBm的饱和输出功率，在1 61 4nm处获得了9 .2d B的信号增益。更多还原

【Abstract】 Since the 1970s, optical fiber communications has made great progress in ashort period of 30 years. The speed of fiber-optic communication has been growingfrom 45Mbits/s to 40Gbit/s. How to use the existing communication system towiden the communication capability in order to meet increasingly demands hasbecome the hotspot of the optical communication research realm, when all kinds ofdata services require more and more transmission bandwidth. Through combinedwith the traditional C-Band erbium-doped fiber amplifier (EDFA), L-Band EDFAcan widen the original gain bandwidth and improve the channel capacityremarkably. So L-band EDFA has become the key device of the new generationDWDM system, it can be realized or not determines the realization of broad bandDWDM system. Comparing with C-band EDFA, L-band EDFA has its particularcharacter in widen mechanism, gain, how to choose pump wavelength and power,power conversion efficiency and so on. How to optimize the design of L-bandEDFA has become a new request for optical communication. Therefore, thedevelopment of L-Band EDFA has great significance for the enhancement of thefuture fiber communication system capacity.Under this background, the author develops two kinds L-band EDFAinstructed by Processor Guo Yubin during the postgraduate study. Through theintroduction of a single optical fiber Bragg grating (FBG), better gain clampingresults and bigger gain figure were obtained. This paper studied and had carried onthe experiment in the expectation of offering the theory and experiment referencefor the methods of L-band EDFA.First, the thesis introduced the background knowledge such as: theclassification, application of optical amplifiers and the development of EDFA. Atthe same time, the paper carried out the theoretically analysis on the characteristicof Er ion in erbium-doped fiber, especially on the principle of EDFA and itsamplified performance, the Gils model, one of the most used models in theoreticalcalculations, is also derived. Second, several important performance parameters of L-band EDFA isintroduced. The measurement of noise figure is discussed in detail. According tothe following experiments, the reflected spectrum of FBG is measured. Then theamplified spontaneous emission (ASE) spectrum characteristic of the designedconfiguration is studied. According to the ASE spectrum characteristic, adjusted thefiber structure in the experiment to achieve more satisfactory results.Finally, the paper studied linear cavity and ring-shaped cavity L-Banderbium-doped fiber amplifier. The linear cavity L-Band erbium-doped fiberamplifier adopted two sections EDF as gain medium, 1480nm LD as pump laserfor higher efficiency and lower noise figure (NF). When input 1589nm signal, thegain is clamped at 23dB with a variation of 0.5 dB from input signal power of -30to -8dBm for a pump power of 180mW, and NF below 5dB is obtained. As FBGreflects some ASE back into the EDF, the gain enhances 5dB with inputting smallsignal. The saturated output power for 1589nm is 7dBm. At the longer wavelength(1614nm) in L-band higher gain is also obtained.At the same time, the paper studied L-band EDFA based on ring erbium-dopedfiber laser cavity. When input 1589nm signal, the gain is clamped at 17.5dB with avariation of 0.3 dB from input signal power of -30dBm to -12dBm for a pumppower of 180mW, and NF below 5dB is obtained. By adjusting the intra-cavity loss,the gain reaches 19.78dB with inputting small signal. The saturated output powerfor 1589nm is 8.5dBm. At 1614nm, 9.2dB gain is obtained.The main features of this paper are:1. A novel gain-clamped linear cavity L-band EDFA is proposed andexperimented by using a fiber Bragg grating (FBG) at the input end of the amplifier.This design provides a good gain clamping and decreases noise effectively. AsFBG reflects the backward ASE into the EDF, the small signal gain is improved.Comparing with the previous schemes, higher gain is observed at the longerwavelength at L-band.2. The linear cavity configuration adopts two sections of EDF, 20-m-length high concentration EDF combined with 11-m-length common EDF. The commonEDF is used to generate C-band ASE, then this C-band ASE is utilized to pumphigh concentration EDF. The Experiment results show that this configuration canameliorate gain and NF effectively.3. An L-band EDFA based on ring erbium-doped fiber laser cavity isestablished. By adding a FBG at the output end, the FBG can reflect parts forwardASE into the laser cavity, the signal gain can be clamped consequently. Comparingwith related reports, this configuration also has a good gain clamping. Because1480nm LD and high concentration EDF is used in this experiment, the amplifierhas lower noise figure.As a conclusion, this thesis analyzes the principle, design process, debuggingprocess, output characteristic measuration of L-band Erbium-doped Fiber Amplifier.I hope that these researches could provide worthy theories and the techniquesupport for further research and development.更多还原