| 摘要 |
PURPOSE:To improve the manufacture yield by constituting an elliptical jacket so that both its minor axis direction and major axis direction have the same refractive index. CONSTITUTION:On the outside peripheral part of a core 1, a clad 2 consisting of pure SiO2 glass is provided so as to surround said part, and on the outside peripheral part of the clad 2, an elliptical jacket 3 is provided so as to surround said part. This elliptical jacket 3 consists of SiO2 glass to which B2O3 has been added, and has a refractive index n1 being lower than a refractive index n0 of the clad 2. Also, on the outside peripheral part of the elliptical jacket 3, a support 4 consisting of pure SiO2 glass and having the refractive index n0 being equal to that of the clad 2 is provided so as to surround said part. In this case, the elliptical jacket 3 has an ellipticity of 25-40% and a specific refractive index difference of -0.05--0.3% to the clad. |
