Shibata Nori, Watanabe Kimitaka, Ohashi Masaharu
Appl Opt. 2022 Nov 1;61(31):9305-9310. doi: 10.1364/AO.471795.
A modal interferometer method (MIM) is applied to measure the differential mode delay (DMD) between the modes traversing a step-index multimode fiber (SI-MMF). Only linearly polarized radial modes, i.e., modes, are excited and transmitted in the SI-MMF by using a single-mode-multimode-single-mode (SMS) fiber structure. The measurement principle is based on investigating a transmitted spectrum through temporal decomposition by means of a Fourier transform. The Fourier-transform-based MIM provides simultaneous measurements of the DMD between the modes. The wavelength dependence of the DMD is estimated experimentally in both the 1260-1360 nm and 1450-1625 nm telecommunication bands. The normalized frequency dependence of the DMD is also investigated theoretically. The result suggests that the 1260-1360 nm band is preferable to the 1450-1625 nm band for a mode-division multiplexing (MDM) transmission employing an SI-MMF in terms of realizing a smaller DMD.
一种模态干涉仪方法（MIM）被用于测量穿过阶跃折射率多模光纤（SI-MMF）的各模式之间的差分模式延迟（DMD）。通过使用单模-多模-单模（SMS）光纤结构，仅线性偏振的径向模式，即 模式，在SI-MMF中被激发和传输。测量原理基于通过傅里叶变换进行时间分解来研究传输光谱。基于傅里叶变换的MIM提供了 模式之间DMD的同时测量。在1260 - 1360纳米和1450 - 1625纳米电信频段中通过实验估计了DMD的波长依赖性。还从理论上研究了DMD的归一化频率依赖性。结果表明，就实现更小的DMD而言，对于采用SI-MMF的模分复用（MDM）传输，1260 - 1360纳米频段比1450 - 1625纳米频段更可取。
