An experimental study of the multifiber WDM networks

实验证明，采用双向WDM传输技术可以有效地提高多光纤WDM网络的波长利用率。(1)瑞利后向散射噪声的实验分析虽然已知瑞利后向散射噪声的基本特性，但我们对其进行了实验分析，为后续的实验和理论分析提供参考。我们研制了一套由80公里长的单光纤段和一个光放大器组成的实验装置。首先，我们测量了RB系数，它是-30分贝。然后，测量了RB噪声的偏振度和偏振态(DOP和SOP)。我们确认，DOP接近1/3，RB噪声的SOP与原始光信号相同，两者都如预期。最后测量了光电转换后的RB噪声功率谱。它的形状与原始信号的形状相同，同样如预期的那样。因此，我们从实验上证明了RB噪声的基本参数采用了…RB噪声相加规律的实验分析RB噪声的理论分析假定有多个放大的光中继器段，每个中继器段包含一根长光纤。建立精确的实验装置需要许多光学元件来迫使我们投入大量预算。相反，我们证实了在不同的光纤部分产生的RB噪声增加了它们的功率。因此，我们开发了一种简单的单光纤段和可变增益光学放大器的实验装置，用于模拟来自多个光纤段的累积RB噪声。(3)RB噪声引起的功率损失(PP)的实验分析在上述实验装置中我们测量了PP。我们将实验结果与理论结果进行了比较。我们发现他们之间有很大的不同。我们认为实验结果是可信的，因为它们是在准备充分的情况下进行评估的。我们将回顾由于RB噪声引起的PP的理论分析。较少

We experimentally proved that a bidirectional WDM transmission technique is effective for the multifiber WDM networks to improve wavelength efficiency. Our main results are as follows :(1) Experimental analysis of Rayleigh backscattering (RB) noiseAlthough basic properties of RB noise have been known, we experimentally analyzed it for the references of the following experiments and theoretical analysis. We developed an experimental set-up composed of a single fiber section with 80-km fiber and an optical amplifier. First of all, we measured RB coefficient, which was-30 dB. Then, we measured degree and state of polarization (DOP and SOP) of RB noise. We confirmed that DOP was nearly 1/3 and SOP of RB noise was identical to the original optical signal, both as expected. Finally we measured power spectrum of RB noise after OE conversion. It had an identical shape to that of the original signal, again as expected. As a result, we experimentally proved that basic parameters of RB noise used … More in theoretical analysis were valid.(2) Experimental analysis of additive law of RB noiseTheoretical analysis of RB noise assumed multiple amplified optical repeater sections, each of which contains a long fiber. Building exact experimental set-up requires, many optical components to compel us substantial budget. Instead, we confirmed that RB noise generated in different fiber sections add in their power. Thus, we developed a simple experimental set-up of a single fiber section with an optical amplifier of variable gain for emulating accumulated RB noise from multiple fiber sections.(3) Experimental analysis of power penalty (PP) due to RB noiseWe measured PP in the experimental set-up described above. We compared the experimental results to theoretical results. We found a substantial difference between them. We believe that experimental results are trustworthy because they have been evaluated in a well-prepared situation. We are going to review theoretical analysis of PP due to RB noise. Less