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本论文旨在探讨光纤扭绞时的偏振特性。由于光纤扭绞时折射率分布变得复杂,进行严格的理论探讨相当困难,因此,我们先进行实验性研究,然后用简单模拟方法近似地说明这一结果。并从理论上予以探讨。根据实验结果,确认产生了与入射偏振波分量正交的偏振波成分。此外,从理论上求得了也适用于椭圆纤芯光纤扭绞时的介电常数张量的一般式。根据这一公式,在圆形纤芯条件下,张量的非对角因次只有θ-z 分量(εθ_z),而在椭圆纤芯条件下,还产生γ-θ分量(ε_(γθ))及γ-z 分量(εγ_z)。同时,利用这一介电常数张量,根据作为单模光纤基本模的 HE_(11)模的偶次模和奇次模之叠加,对偏振特性进行了解析。
The purpose of this thesis is to investigate the polarization characteristics of fiber when it is twisted. Due to the complexity of the refractive index distribution when the optical fiber is twisted, it is quite difficult to carry out a rigorous theoretical discussion. Therefore, we first conduct an experimental study and then approximate the result with a simple simulation method. And in theory to explore. From the experimental results, it was confirmed that a polarized wave component orthogonal to the incident polarization component was generated. In addition, the general formula of the permittivity tensor which is also suitable for the twisted fiber of elliptical core fiber is theoretically obtained. According to this formula, the non-diagonal tensor has only the θ-z component (εθ_z) under circular core conditions and the γ-θ component (ε_ (γθ)) under elliptical core conditions And γ-z component (εγ_z). At the same time, by using this dielectric constant tensor, the polarization characteristics are analyzed based on the superposition of even and odd modes of the HE_ (11) mode as the fundamental mode of single mode fiber.