This study accessed the performance of the four-level Manchester coding (4-MC) and four-level modified Manchester (4-MM) technique at the bit rates of 20 and 40 Gb/s for the first-order and second-order optical equalisers. The performances were evaluated with respect to bit error rate (BER), power penalty, eye diagrams, and dispersion tolerance. Based on the results by utilising the second-order optical equaliser, at 20 Gb/s, the transmission distance of 4-MC and 4-MM was extended by 25 and 27 km of standard single-mode fibre (SSMF), respectively, while at the bit rate of 40 Gb/s, the 4-MC and 4-MM transmission distance was extended by 6.5 and 7.5 km of SSMF, respectively. Hence, the second-order optical equaliser can adequately compensate for the fibre dispersion and consequently the overall BER performance. Therefore, the proposed system could serve as an alternative to the next-generation high-speed optical transmission links.

中文翻译：

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带有光学均衡器的多级曼彻斯特（2位/符号）编码，可增加高速光纤链路的传输距离

这项研究获得了四阶曼彻斯特编码（4-MC）和四级修改曼彻斯特（4-MM）技术在一阶和二阶光学的比特率分别为20和40 Gb / s时的性能。均衡器。针对误码率（BER），功率损失，眼图和色散容忍度评估了性能。根据利用二阶光学均衡器的结果，在20 Gb / s时，4-MC和4-MM的传输距离分别扩展了25 km和27 km的标准单模光纤（SSMF），而以40 Gb / s的比特率，4-MC和4-MM的传输距离分别扩展了6.5和7.5 km的SSMF。因此，二阶光学均衡器可以充分补偿光纤色散，从而补偿整个BER性能。因此，