空分复用光纤放大器增益均衡技术研究进展

随着第五代移动通信技术的正式商用,全球网络流量的需求呈爆炸式增长,传统单芯单模光纤通信系统的容量已接近香农极限,实现通信系统的升级扩容迫在眉睫。空分复用光纤通信系统基于空间维度复用,可有效解决未来通信系统的扩容难题,而空分复用光纤放大器是不可或缺的核心器件和研究焦点之一。当多信道功率增益不均衡时,功率差将会随传输距离的增加不断累积,导致中断概率和接收端误码率升高,最终直接影响系统的传输性能,如何实现增益均衡是空分复用光纤放大器所必须解决的关键问题。依据目前已报道的理论与实验研究,从光纤结构设计、折射率掺杂剖面优化和泵浦方式选择等多角度阐述了空分复用光纤放大器增益均衡的工作原理、特点和不足,从而为空分复用光纤通信系统的优化设计和性能的提升提供解决思路与技术方案。

Review on Gain Equalization Technology of Fiber Amplifier Using Space Division Multiplexing

With the commercialization of the fifth-generation mobile communication technology, the global network traffic is exploding. However, due to the proximity to the Shannon limit, the capacity of the traditional single-core single-mode fiber communication system is unsatisfactory in the future network construction. In order to meet the upcoming challenges, it is urgent for us to upgrade the communication system for capacity expansion. To this end, fiber communication systems using space division multiplexing(SDM), dividing the channels in the spatial dimension, can accelerate the capacity expansion of communication systems. In an SDM system, the fiber amplifier has always been one of the most indispensable devices and has become a research hotspot. In the amplifier, when the power gain is unbalanced among channels, the power difference will accumulate with the transmission distance, leading to an increase in the outage probability and bit error rate at the receiver. Eventually, the transmission performance of the system is directly affected. Thus, achieving the gain equalization among different channels is a key to the SDM fiber amplifiers. In this paper, according to the theoretical and experimental researches, we review the gain equalization technology of SDM fiber amplifiers, including fiber structure design, refractive index doping profile optimization, and pump mode selection. Besides, the working principle, structural characteristics, and deficiencies are analyzed in detail, which provides solutions for the optimal design and performance improvement of SDM fiber communication systems.