The optical fiber communication network is the important infrastructure for the modern information society. Thanks to the reduction of fiber loss, the improvement of transceiver devices by electro-optical-electrical conversion, the development of modulation technology and the introduction of digital signal processing, the capacity of optical fiber transmission has been greatly improved. In recent years, due to the large capacity demand of data-centers and the next-generation wireless communication, metro and short-range transmission scenarios below 100 km have attracted lots of attention based on direct detection. The historical evolution of optical fiber communication systems was firstly reviewed, then the limiting factors in the direct detection system were analyzed. Furthermore, the principle and system configuration of one-dimensional to four-dimensional self-coherent technology were introduced, and finally, the low-cost evolution trend of the optical coherent transmission system was prospected.%光纤通信网络是现代信息社会的重要基础设施.随着光纤损耗的降低、电—光—电转换器件性能的提升、调制技术的发展和数字信号处理的引入,光纤传输系统的容量获得了极大的提升.近年来,由于数据中心和移动通信升级的需求,光纤传输的研究热点逐步转向100 km以下基于直接检测的中短距传输场景.为此,首先回顾了历代光纤通信系统的历史演进,然后分析了直接检测系统中的限制因素,在此基础上依次介绍一维至四维自相干光检测技术的原理和系统配置,最后展望了未来相干光通信系统的低成本演化趋势.
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