A new type of bidirectional coherent optical communication system is proposed combining unidirectional optical signal amplification. We analyze the application of discrete Raman amplifier (DRA) on the basis of dispersion compensating fiber in this system, and optimize the amplifier configuration considering the influence factors such as Rayleigh backscattering noise and amplified spontaneous emission noise. In addition, the gain and pump efficiency improvement in a novel design of double-pass DRA. The feasibility of the single-fiber bidirectional coherent optical communication system is ensured by the theoretical analyses and MATLAB coding. The system greatly decreases the phase shift problem caused by the frequency offset between the transmitter and local oscillator as well as the laser linewidth. It has practical value for secure communication systems.

中文翻译：

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结合单向光信号放大的双向相干光通信系统

提出了一种结合单向光信号放大的新型双向相干光通信系统。分析了基于色散补偿光纤的离散拉曼放大器（DRA）在该系统中的应用，并考虑瑞利背向散射噪声和放大自发辐射噪声等影响因素优化放大器配置。此外，新型双通 DRA 设计中的增益和泵浦效率提高。理论分析和MATLAB编码保证了单纤双向相干光通信系统的可行性。该系统大大减少了由发射机和本地振荡器之间的频率偏移以及激光线宽引起的相移问题。