具有多个点损耗的DFRA开关增益定量分析模型

The Quantitative Aalysis Mode of DFRA On/off Gain with Multiple Localized Loss in Fiber

基于忽略泵浦光损耗的正向拉曼光纤放大器耦合方程,推出光纤中存在多个熔接(点)损耗情况下正向(及反向)泵浦光的分布式拉曼光纤放大器(DFRA)增益的定量分析模型,进而推出由不定长光纤小段、且各小段增益系数不同、各小段之问存在熔接(点)损耗DFRA增益的定量分析模型。并针对DWDM系统的增益模型,在考虑了熔接点对信号光之间产生的泵浦作用的损耗,将上述模型进行了修订。上述两种情况下的模型,较之以往的定性的分析文献[3][4]给出定量分析公式和明确的物理解释,并指出熔接损耗点越靠近泵浦光的输入端,对DFRA拉曼开关增益的影响越大(使其越小)。为了考查模型的正确性及适用性,由具有泵浦光之间、信号光之间、泵浦光及信号光之间反相DFRA耦合方程的仿真程序进行了验证,误差不超过0.02dB。最后得出对实际DFRA设计十分有益的结论:当每3公里一个熔接点损耗系数小于0.092dB 时(实际系统中最坏情况下损耗有0.1dB),跨距小于120公里的拉曼光纤放大器的开关增益较无熔接点损耗时下降小于10%。这说明在已铺设的光纤传输系统中使用拉曼放大器是可行的,本文中具有点损耗的DFRA开关增益公式可作为实际DFRA系统设计参考标准。

The quantitative analysis mode of DFRA on/off gain with multiple localized loss in fiber is deduced from the non-depletion simple Raman approximate equations based on co-propagating pump (or back pump), then, the quantitative analysis mode is modified based on the fiber formed by varied fiber length with multiple localized loss between them and varied Raman gain efficiency of each varied fiber. The mode is modified in DWDM system while considering the multiple localized loss affect the signal-to-signal stimulated and spontaneous Raman scattering gain. In order to check the validity and the applicability of the above mentioned two modes. The quantitative analysis expression of the two modes whose error do not exceed 0.02dB (compared to reference [3] and [4] that only show qualitative analysis) has been validated by simulated back-pumped fiber Raman amplifier with multiple signal and pump channels whose system of coupled equations has taken into account pump-to-pump, pump-to-signal, and signal-to-signal stimulated and spontaneous Raman scattering. The profitable conclusion can be deduced: the on/off gain of the DFRA with one splice loss less than 0.092dB per 3km, (the whole length does not exceed 120km) will not descend to the 90% on/off gain of the DFRA with no splice. The result shows that it is feasible to apply DFRA to the paved fiber system. The two modes of this paper can be used as real DFRA system design reference.