【作者】 张昊；

【导师】 袁树忠； 刘艳格；

【作者基本信息】 南开大学 ， 光学， 2005， 博士

【摘要】 掺铒光纤放大器的出现是光纤通信发展史中重要的里程碑,EDFA使用全光中继来代替了光-电-光中继,极大地降低了系统的成本和延长了信号传输的距离,同时还推动了WDM/DWDM通信系统的整体发展。WDM/DWDM通信系统的发展又需要EDFA具有更大的带宽、优良的增益和噪声特性和增益控制等功能。基于上面的情况,并结合天津市重点基金项目——智能光纤放大器光源的研究、天津市重点基金项目——(C+L)超宽带掺杂光纤放大器和南开-达尔泰(天津)项目——开发增益平坦的掺铒光纤放大器等课题,论文主要围绕新型增益控制EDFA、增益控制用光源、多波长激光器及可调光衰减器、EDFA性能优化和超宽带EDFA等方面进行了理论和实验研究。主要工作如下:1.首次提出了基于双折射光纤环镜优化L-band EDFA噪声性能的方案。利用双折射环镜的梳状反射特性抑制双通EDFA的ASE,从而使放大器的噪声性能得到了明显改善。基于双折射光纤环镜的L-band EDFA比用普通光纤环镜的放大器的平均噪声低3.7dB。2.首次提出基于光纤起偏器和双折射光纤环镜的多波长掺铒光纤激光器。通过双折射光纤环境反射器和光纤起偏器来控制腔内偏振态,实现了利用偏振烧孔效应的多波长掺铒光纤激光器。实验中获得了4波长和5波长的稳定的激光输出,其波长间隔小于2nm。另外,我们还利用光纤起偏器和双折射光纤构成Lyot滤波器作为选频器件,同时通过利用腔内双折射增强偏振烧孔效应构成了可以获得稳定双波长输出的线形腔掺铒光纤激光器。实验上得到了两组间隔分别为3.44nm和1.56nm的L波段双波长激光,而且通过调整偏振控制器还得到的由1599.28nm~1605.84nm的五个单波长激光。3.首次提出利用前置放大器提高双通EDFA增益与噪声性能的方案。通过在基于普通光纤环镜的L-band EDFA前面加入一段已被泵浦的铒纤提高了输入端的铒离子的粒子数反转程度,使普通的双通L-band EDFA性能得到了改善。同普通双通放大器相比,在约1568nm~1594nm的范围内,加入前置放大器的L-band EDFA的增益提高了2.3dB~12.6dB,而噪声系数降低了2.2dB~23.9dB。4.提出了一种基于光纤环形镜对L-band EDFA增益控制的方法。输入信号光功率在约-40dBm~-15dBm的范围内,1595nm处反馈光衰减量为0时的增益波动和饱和输出功率比衰减量为4dB(控制光强度较弱)时的情况分别降低了0.33dB更多还原

【Abstract】 The emergence of erbium-doped fiber amplifier is the landmark in the history of optical fiber communication. By utilizing EDFAs, all-optical relay is realized, transmission distance is much lengthened, and the development of WDM/DWDM (Wavelength-Division Multiplexing/Dense WDM) communication systems is generally accelerated. Meanwhile, with the development of WDM/DWDM communication systems, more and more attention is paid on the EDFAs with broader bandwidth, good gain and noise feature, and gain clamping, etc.According to the Tianjin Natural Science Foundation project: Intelligent fiber amplifiers and light sources, the Tianjin Natural Science Foundation project: (C+L) broadband fiber amplifier and the Nankai-Delta (Tianjin) project: Development of gain flattened erbium-doped fiber amplifiers, this dissertation is mainly focused on the study of novel gain-clamped EDFA, light sources, multi-wavelength fiber laser and variable optical attenuator for gain-clamped usage, gain and noise improvement of EDFA, and broadband EDFA. The main contents are listed as follows:1. A noise figure improved L-band EDFA based on Hi-Bi (high birefringence) fiber loop mirror as ASE rejecter is presented for the first time. By utilizing the comb-like reflection spectrum of a Hi-Bi fiber loop mirror to suppress the ASE (amplified spontaneous emission) of a double-pass EDFA, the noise figure of this amplifier is much improved. The average noise figure of the double-pass L-band EDFA based on Hi-Bi fiber loop mirror is 3.7dB lower than that of the one based on a common fiber loop mirror.2. A multi-wavelength erbium-doped fiber laser based on fiber polarizer and Hi-Bi fiber loop mirror is put forward for the first time. By utilizing Hi-Bi fiber loop mirror and fiber polarizer to control the intracavity polarization state, a multi-wavelength erbium-doped fiber laser by exploiting PHB (polarization hole-burning) is realized. We have experimentally achieved four-wavelength or five-wavelength stable lasers with wavelength spacing of less than 2nm. Moreover, by using fiber polarizer and birefringence fiber to constitute a Lyot filter, the intracavity PHB effect is enhanced and a dual-wavelength linear cavity erbium-doped fiber laser is achieved. We have experimentally obtained two series of L-band dual-wavelength lasers with wavelength spacing of 3.44nm and 1.56nm, respectively. Furthermore, by tuning the polarization controller, five single-wavelength lasers ranging from 1599.28nm to 1605.84nm can be also acquired.更多还原