| 摘要 |
PURPOSE:To obtain the optical fiber which can be easily produced, can be reduced in cost and mass produced and has small crosstalks by constituting the fiber of a core having an elliptic sectional shape and a clad enclosing the core and lowering the softening point temp. of the clad lower than the softening point temp. of the core. CONSTITUTION:This optical fiber consists of the core 11 having the elliptic sectional shape and the clad 12 enclosing the core. The softening point temp. of the clad 12 is set lower than the softening point temp. of the core 11. Such optical fiber is formed by drawing a fiber base material consisting of the elliptic core material and the clad material. Since the softening point temp. of the core material is higher than the softening point temp. of the clad material, the axial stress remains in the core 11. Stress anisotropy is induced in the section of the optical fiber from this axial residual stress, by which the double refractive index of modes is generated. The optical fiber which can be easily produced, can be reduced in cost and mass produced and has the small crosstalks is obtd. in this way. |
