An experimental study of the multifiber WDM networks

实验证明了双向WDM传输技术对提高多纤WDM网络的波长利用率是有效的。主要研究结果如下：（1）瑞利后向散射（RB）噪声的实验分析虽然RB噪声的基本特性已经被人们所了解，但我们还是对其进行了实验分析，为后面的实验和理论分析提供参考。我们开发了一个实验装置组成的一个单一的光纤部分与80公里的光纤和光放大器。首先，我们测量RB系数，其为-30 dB。然后，我们测量了RB噪声的偏振度和偏振态（DOP和SOP）。我们证实了DOP接近1/3，RB噪声的SOP与原始光信号相同，两者都符合预期。最后测量了OE转换后RB噪声的功率谱。它的形状与原始信号的形状相同，再次符合预期。实验结果表明，所用RB噪声的基本参数 关于我们 理论分析是有效的。(2)RB噪声加性规律的实验分析RB噪声的理论分析假设多个放大光中继段，每个放大光中继段包含一根长光纤。建立精确的实验装置需要，许多光学元件，迫使我们大量的预算。相反，我们证实了在不同的光纤段中产生的RB噪声增加了它们的功率。因此，我们开发了一个简单的实验装置，一个单一的光纤部分与可变增益的光放大器，用于模拟从多个光纤部分积累的RB噪声。(3)由于RB噪声导致的功率损失（PP）的实验分析我们在上述实验设置中测量了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。我们相信实验结果是值得信赖的，因为它们是在充分准备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。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