Gloge D, Chinnock E L, Ring D H
Appl Opt. 1972 Jul 1;11(7):1534-8. doi: 10.1364/AO.11.001534.
Incoherent light, transmitted via multimode fibers, represents a potential carrier for information that is directly modulated on the light envelope. The amplitude and phase characteristics of the envelope (baseband) signal are affected by the fiber waveguide because of group delay differences among the modes. We report on a technique that determines the baseband frequency response of the fiber system by comparing the beat spectra of light from a free-running laser before and after transmission through the fiber. As an example, we describe the measurement of 30 m of cladded multimode fiber. The 3-dB bandwidth was 700 MHz, somewhat larger than predicted on the basis of the computed group velocity differences.
通过多模光纤传输的非相干光代表了一种在光包络上直接调制信息的潜在载体。由于各模式之间的群时延差异，包络（基带）信号的幅度和相位特性会受到光纤波导的影响。我们报告了一种通过比较自由运行激光器发出的光在通过光纤传输前后的拍频光谱来确定光纤系统基带频率响应的技术。作为一个例子，我们描述了对30米包层多模光纤的测量。3分贝带宽为700兆赫，略大于根据计算出的群速度差异所预测的值。
