光纤放大和光孤子长途通信

Long Distance Optical Fiber Communications Using Fiber Amplifiers and Solitons

本文简述十余年来光纤通信从常规系统进化至新型系统所经历的过程,传输容量Gb/s·km以每四年增大十倍的速率前进。文中着重说明长途单模光纤线路中间装置掺铒光纤放大器,实现全光传输,不用再生中继机,每一光纤放大器在0.98μm或1.48μm激光管功率的抽引下,对1.55μm信号提供增益30dB。用12个光纤放大器,可使数字速率2Gb/s传输1000km成为实用的长途通信系统。最近实验室报道表明有可能使传输容量加大至50 000Gb/s·km。文中还介绍了光孤子通信实验的进展,在设置光纤放大器的1000km光纤线路上,获得光纤似的长途通信系统,由于光纤非线性抵消了色散效应,很窄的脉冲以很高的数字速率经过越长距离的传播,仍不呈现显著的脉冲展宽,和畸变及噪声影响。这种系统对越洲的陆地线路和越洋海底光缆极为有利。

The paper reviews the evolution of optical fiber communicationsfrom conventional systems to new-generation systems in view of increasein transmission capacity, Gb/s. km. In particular, it describes the newsystems using Erbium-doped fiber amplifiers along the long distance singlemode optical fiber line, each of which provides gain 30 dB to 1. 55μmsignals under pumping at 0. 98μm or 1. 48μm by laser diodes. It becomesall-optical transmission without regenerative repeater, and is practical foruse at digital rate 2Gb/s and distance 1000km with 12 fider amplifiers.Laboratory experiments reported that still greater transmission capacityup to 50000Gb/s. km could be obtained. The paper also describes thetechnical progress on soliton experiments. On the 1000km line equippedwith intermediate fiber amplifiers, sliton-like communication system isfound possible. Due to compensation of dispersion effect by fiber non-linearity, very narrow pulse at very high digital rate could propagate over ultra-long distance without significant pulse-broadening, distortion andnoise interferences. Apparently, such systems are expected to be usefulfor trans-continental terrestrial line and transoceanic submarine cable.