Abstract For the cladding removed multimode fiber, when the refractive index of the external solution is close to the fiber core, it will cause refractive-index-matched coupling effect. In this work, the appearance of two index-matched points was observed. One of the index-matched point located at short wavelength, which had not been reported previously. Then, magnetic fluid was used as the external solution around the fiber core. As magnetic fields of different intensities were applied, the refractive-index-matched coupling effect occurred, which was different from that happening within isotropic solution. The observed phenomenon was mainly due to the anisotropy of the magnetic fluid under magnetic field. Based on the establishment of theoretical model and formulation of empirical equation, numerical simulations were also employed to further investigate the refractive-index-matched coupling within the anisotropic solution.

中文翻译：

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由包层去除多模光纤周围的磁流体产生的折射率匹配耦合

摘要 对于去除包层的多模光纤，当外溶液的折射率接近纤芯时，会引起折射率匹配耦合效应。在这项工作中，观察到两个索引匹配点的出现。索引匹配点之一位于短波长处，以前未报道过。然后，磁流体用作围绕纤芯的外部溶液。当施加不同强度的磁场时，会出现折射率匹配的耦合效应，这与各向同性溶液中发生的情况不同。观察到的现象主要是由于磁流体在磁场作用下的各向异性。在建立理论模型和建立经验方程的基础上，