| 摘要 |
PURPOSE:To facilitate the formation and to reduce the connection loss by heating a part of an elliptic core type polarization plane maintaining optical fiber which has noncircular spot size and making its elliptic core round. CONSTITUTION:Quartz soot is provided externally on the outer periphery of a glass rod by an external CVD method or VAD method to obtain calcined glass and at this time, the sectional shape of the worked rod is made noncircular according to its viscosity difference to form the elliptic core 1. Then a glass base material is used as an optical fiber base material and drawn in a drawing furnace into a fiber with the drawing tensile force within a range wherein the initial noncircular sectional shape can be maintained. Then the obtained optical fiber which is as long as desired is prepared and a part of it is heated with a burner to make the core 1 which is in an elliptic shape close to a rectangular shape into a circular core 11 gradually. Consequently, the spot size converting optical fiber which can perform conversion from an ellipse to circular spot size without any loss can easily be obtained. |
