【作者】 李晓光；

【导师】 胡贵军；

【作者基本信息】 吉林大学 ， 通信与信息系统， 2011， 硕士

【摘要】 通信业务容量在爆炸式增长,大容量、长距离的DWDM干线传输技术的发展及日益复杂的光网络拓扑结构,需要饱和输出功率较高的光放大器。Er/Yb共掺双包层光纤放大器（EYDFA）,在Er³⁺离子掺杂的基础上,加入了相当比例的Yb³⁺离子,解决了Er³⁺离子掺杂浓度过高时的浓度淬灭问题,抑制了自脉冲效应,且加宽了吸收谱;此外,基于双包层结构光纤的包层抽运技术,提高了泵浦光的吸收效率,降低了对抽运光的单模要求。Er/Yb共掺双包层光纤放大器以其在1550nm光通信波段的高饱和输出功率,来满足光纤通信技术对放大器日益增加的功率需求,具有广泛的应用前景。本文给出了Er/Yb共掺双包层光纤放大器的理论模型及求解方法,在此基础上采用光学设计软件对放大器各参数进行了仿真优化,基于仿真优化的结果,搭建了放大器的实验系统并测试了其输出性能,实现了信号功率10dBm,抽运电流8A的情况下,最大30.29dBm （1.07W ）的功率输出。论文具体工作内容如下:首先,阐述了Er/Yb共掺双包层光纤放大器中Yb³⁺离子作为敏化剂的作用,以及双包层的光纤结构在实现高功率放大方面的优势,介绍了不同的内包层形状对包层抽运耦合效率的影响。分析了放大过程中Er/Yb共掺能级系统中的能量传递关系,据此给出了放大器基于速率方程和功率传输方程的理论模型,根据离子活动的特点对模型进行了简化并给出了其稳态情况下的四阶Runge-Kutta数值求解方法。根据方程的求解结果,给出了在不同的信号、抽运功率条件下,放大器增益随光纤长度的变化情况。较为全面的介绍了实现双包层光纤放大器的关键技术—包层抽运耦合技术。其次,以基于速率方程和功率传输方程的放大器理论模型为基础,采用光学设计软件对放大器各参数进行了仿真优化。搭建了前向、后向、双向三种不同抽运方式下放大器的仿真模型,并对其性能进行了对比分析。研究了不同信号光、抽运光输入时的放大特性,对有源光纤长度、稀土离子掺杂浓度、包层大小等参数对放大器输出性能的影响进行了分析。对双级结构的放大器和放大器的脉冲放大特性进行了初步研究。最后,根据对放大器各参数仿真优化的结果,搭建了前向抽运的Er/Yb共掺双包层光纤放大器。实现了信号功率10dBm ,抽运电流8A的情况下,最大30.29dBm （1.07W ）的功率输出,以及同样8A的抽运电流下,信号光功率为? 10dBm时,33.48dB的放大器最大增益。测试了放大器在不同的抽运功率条件下,对不同功率、不同波长输入信号光的放大输出性能,并分析了信号光功率、波长及抽运功率对放大器性能的影响。简述了放大器放大过程中自激振荡产生的原因及其与信号光、抽运光功率的关系。本文在对放大器理论分析的基础上,仿真优化并实验研究了Er/Yb共掺双包层光纤放大器的输出性能。实验输出与仿真优化结果的变化趋势是一致的,但由于仿真模型与实际放大器存在的一定差异性、各器件的理想化以及实际实验当中存在熔接损耗、插入损耗等因素,导致了实验所测放大器的输出与放大器仿真优化结果存在着一定的差距。更多还原

【Abstract】 The capacity of communications business is increasing explosively. The development of large capacity, long-distance DWDM trunk transmission technology and increasingly complicated optical network topology need optical amplifiers of high saturated output power. On the basis of the doped Er³⁺ ions, Er/Yb co-doped double-clad fiber amplifier（EYDFA） incorporate a considerable proportion of Yb³⁺ ions. This can resolve the concentration quenching caused by high concentration of Er³⁺, inhibit self-pulsing and widen the absorption spectrum. In addition, based on double-clad fiber, the cladding pumping technology increases the pump absorption efficiency, and reduces the requirements of single-mode pump. With the high saturated output power in the optical communication wavelength of 1550nm, Er/Yb co-doped double-clad fiber amplifier can meet the growing power demand of the amplifier which is needed by fiber communications technology. So it has a broad application prospect.This paper gives the theory model and solution of Er/Yb co-doped double-clad fiber amplifier. On this basis, the parameters of amplifier are simulated and optimized by optical design software. On the result of optimization, the amplifier experimental system is established, and the performance of the amplifier is tested and analyzed. Under the condition of 10dBm signal power and 8A pump current, maximum output power of 30.29dBm（1.07W） is obtained. The works done in this paper are as follows:Firstly, the effect of Yb³⁺ ions as sensitizer and the advantage of double-clad fiber structure in the high power in Er/Yb co-doped double-clad fiber amplifier are expounded. The effect of different inner cladding shapes on pump coupling efficiency is introduced. The energy transfer relationship of Er/Yb co-doped system is analyzed, and hereby the theoretical model of amplifier based on rate equations and power propagation is given. The model is simplified according to the ion activity characteristics and the numerical solution of fourth-order Runge-Kutta method during steady-state is given. According to the results of the equations, the changes of amplifier gain with fiber length under the condition of different signal and pump power are also given. As the key technology of double-clad fiber amplifier, the clad pump coupling technology is introduced comprehensively.Secondly, based on the amplifier theoretical model of rate equations and power propagation, simulation and optimization of the amplifier parameters are made by optical design software. The amplifier simulation models in three different ways of forward, backward and bi-directional pumping are established, and their performance is compared and analyzed. The amplification characteristics under the condition of different signal and pump power are researched. The effect of the parameters such as active fiber length, doping concentration ratio of rare earth ions and cladding size etc. on amplifier output performance is analyzed. The amplifier of two-stage structure and pulse amplification are preliminary studied.Finally, according to the result of simulation and optimization on amplifier parameters, Er/Yb co-doped double-clad fiber amplifier with the forward pumping is established. The maximum output power of 30.29dBm（1.07W） is obtained under the condition of 10dBm signal power and 8A pump current. And the maximum amplified gain of 33.48dB is obtained under the condition of -10dBm signal power and also 8A pump current. The amplification characteristics to different power and wavelength of input signal light under the condition of different pump power are tested. And the effects of signal power, wavelength and pump power on amplification characteristics are analyzed. The causes of self-oscillation in amplification process and the relationship with signal and pump power are briefly introduced.Based on the theory analysis, this paper simulates, optimizes and experimentally researches the output performance of Er/Yb co-doped double-clad fiber amplifier. The trend between the experimental output and the optimization result is consistent. However, due to some differences between the simulation model and the actual amplifier, idealization of devices, the splicing loss, insertion loss and other factors existing in actual experimental, some gap between amplified output in experimental and the optimization result of amplifier still exist.更多还原