| 摘要 |
PURPOSE:To prevent the increase of the coupling loss and to reduce the scattering loss, by attaching two glass rods having a larger coefficient of thermal expansion than a glass rod at both sides of this glass rod and covering these glass rods with a glass tube. CONSTITUTION:A glass rod 13 having a high coefficient of thermal expansion is attached and melt-stuck at both sides of a glass rod having a core 11 and a cladding layer 12. These glass rods are covered with a glass coat 14. Then these glass rods are heated at a high temperature, and the rod 13 contracts greatly when it is cooled down to the normal temperature from a high temperature. As a result, the core 11 is turned into the double refractive glass. A polarization preserving fiber is obtained owing to the double refractive properties. In this case, the coupling loss does not increase with reduction of the scattering loss since the core 11 is kept circular. |
