【作者】 胡永刚；

【导师】 陈险峰； 田翔庆；

【作者基本信息】 上海交通大学 ， 光学工程， 2012， 硕士

【摘要】 由于掺铒光纤放大器EDFA可直接对光信号放大，不再需要传统光通信所用的“光－电－光”的放大模式，降低了系统的成本，简化了系统，因此在光纤通信系统中具有广阔的应用前景。而在不断有信号上传、下载的波分复用系统中，掺铒光纤放大器的增益控制技术具有重要的意义。密集波分复用（DWDM）技术使得通信带宽大大增加，是目前开发和应用的热点。它的发展对光纤放大器提出了更高的要求，譬如要求光纤放大器具有更大的带宽，具有功率控制等功能。但是光纤通信系统的发展也面临一些问题，如传统的带宽已不能满足WDM系统传输容量的要求，因此对于L波段EDFA的研究就显得尤为重要。由于不同波长的光在光纤中的传输损耗不同，随着波长增大，损耗减小，信号光进入EDFA前会产生一个倾斜度；此外受激拉曼散射效应导致功率从短波长向长波长转移，产生倾斜度。因此控制EDFA的增益斜率来补偿输由于光纤损耗和受激拉曼散射而产生的倾斜度，可以使L波段光纤传输系统的输出光功率更平坦。本论文研究了影响EDFA增益斜率的主要因素。在研究过程中讨论分析了目前的大部分文献中对于EDFA增益谱只是讨论增益平坦的问题而很少有关于增益斜率研究的原因，进一步分析了增益斜率研究的重要性。探讨了目前主要传统的控制增益斜率的方法。现阶段传统的控制增益斜率方式是通过改变增益可调EDFA中的VOA，但是其动态增益范围不够大而且由于VOA本身的限制会带来较大的噪音和较高的成本；此外RED-C公司提出了比较创新的基于多种长度光纤和光开关阵列的增益开关增益可调EDFA方式，但是其结构庞大而且成本也较高。通过对这些控制增益斜率方法的研究，本文提出了在普通的L波段增益可调掺铒光纤放大器中采取控制光纤的温度的方式来控制整个放大器的增益斜率，从而使增益可调光纤放大器既有很宽的增益调整范围，又可以通过可控制增益斜率来避免信号失真和噪音等问题。论文通过实验验证了温度控制增益斜率的可行性。同时，通过光纤的温度来控制增益斜率的话，只需要在EDFA中加入温度控制单元，而温度控制单元的体积小，造价低，因此通过温度控制增益斜率进而达到宽范围增益可调的掺铒光纤放大器是一种可以商业化生产的低成本解决方案。更多还原

【Abstract】 Erbium-Doped Fiber Amplifier (EDFA) can amplify signals directly, which can avoid tousing “light-electric-light” amplified mode as traditional light communication system andsimplifies communication systems, and improve communication system cost, so it willachieve wide applications in fiber communication systems in future.WDM/DWDM (Wavelength Division Multiplexing/Dense WDM) system has alreadybroadened the bandwidth of optical fiber communication system, and become the majortechnology of exploitation and application. But in the long-distance, high-speed WDMsystems using EDFA is also facing some problems. For example, WDM system requiredmore bandwidth of transmission capacity, network management, so the study for L-BandEDFA application becomes more and more important. Since the different wavelengths of lightin optical fiber have different transmission loss, as the wavelength increases, the loss isreduced; the signal light will have an inclination before enter into the EDFA. In addition, thestimulated Raman scattering effect which lead to the power transfer from short wavelength tolong wavelength to produce the tilt. Therefore, control of EDFA gain tilt to compensate forlost due to fiber loss and stimulated Raman scattering, which can make the output opticalpower of the L-band optical fiber transmission system more flat.In this thesis, the main factors affecting the gain tilt of the EDFA was discussed and analyzed. In the course of this study, we find the most of the current literature focused only on theEDFA gain spectrum with gain flatness technology, while there is little study on gain tilt andthen explored in this thesis with the importance to study for the gain tilt. The main traditionalmethod of control the gain tilt of EDFA was discussed.Current traditional method of control gain tilt is changing the attenuate range of VOA insideof EDFA, but EDFA’s dynamic gain range is not big enough by this method because thehigher attenuate range of VOA will bring much more noise and higher costs; In addition, theRED-C corporate clarified a new innovative type of gain switched variable gain EDFA basedon a variety of length of optical fiber and optical switch array to change control the gain tiltof EDFA, but it will cause to complexity structure and also higher cost. To considering botheffected factors for gain tilt and the traditional gain tilt control methods, we bring forward anew scenario to get gain flattened signal output by adjust the gain tilt using the method ofcontrolling the temperature of the erbium-doped fiber in a normal variable gain EDFA, thenthe variable gain EDFA can have a wide variable gain range, and also can avoid signaldistortion and noise issue. Also, an experiment was set to verify the scenario. To controlfibers temperature, it only need to add temperature control unit inside of the variable gainEDFA module, the temperature control unit in the EDFA can be smaller size, lower cost.Based on the experiment results, we can try to use a simply temperature control unit toachieve a wide range of variable gain EDFA by improving the gain tilt, it can be easily turn tomass production for industrial production factory.更多还原