| 摘要 |
PURPOSE:To produce a titled optical fiber of low loss by forming a clad consisting of specific glass having an elliptical section on the outside circumference of a core having a circular section and an outer clad having a circular section. CONSTITUTION:A glass film 43 that forms an elliptical clad 22 consisting of SiO2+P2O5B2O3 contg. 5-20mol% P2O5 and B2O3 in total and the balance SiO2 is formed on the inside surface of a transparent quartz glass tube 44, and further a high purity glass film to form a circular core 21 is attached on the inside surface thereof. One end of such glass tube 54 is sealed and the inside of the tube 54 is evacuated through the other end with an evacuating device 57 to 0.5-15mm. H2O. While the tube is heated with an oxyhydrogen burner 46, the burner 46 is moved to make the tube 64 solid; thereafter, the solid tube is drawn under heating, whereby the constant polarization type optical fiber having the elliptical clad 22 and the circular outer clad 23 on the outside circumference of the circular core 21 is obtained. |
