| 摘要 |
PURPOSE:To enlarge a double refraction in a core, and to obtain a practical optical fiber whose loss is low, by allowing a core material itself to have an anisotropy, and providing a stress giving part opposingly on both sides of the core material. CONSTITUTION:The titled optical fiber is constituted of a core 1 consisting of a refractive index anisotropic medium, a clad 2 consisting of an isotropic medium for surrounding the core, and a stress giving part 4 provided opposingly on both sides of the core in a clad, and as for two fundamental modes peculiar to the core 1, the polarized wave directions are made orthogonal to each other, and one and the other become a propagation mode and a radiation mode, respectively. That is, the stress giving part 4 is placed in the direction for emphasizing the double refraction in the core, so as to form a relation of ne<nz<no to a refractive index nz, when a refractive index of a double refraction core 5 is denoted as no and ne with respect to an electric field in the (x) direction and an electric field in the (y) direction, respectively. Accordingly, in an HE11<x> mode, a propagation can be executed, but the HE11<x> mode becomes a radiation mode, and the propagation becomes impossible, therefore, an absolute single state for propagating only one polarized wave becomes possible. In such a way, an absolutely single polarized wave optical fiber of a low loss is obtained. |
