PURPOSE: To obtain the titled optical fiber haing unchangeable polarization characteritics easily and inexpensively, by using a commercially available high-purity quartz tube as a side rod for providing strain, using a high silicate glass having improved processability instead of a quartz tube for forming the second clad layer.
CONSTITUTION: The high-purity quartz rods 24 having a refractive index equal to that of a clad part and a diameter larger than the parent material 21 is put on both sides of the solid rod parent material 21 consisting of a core part and the clad part having different refractive indexes. They are inserted into the thick high silicate glass tube 26 having higher coefficient of linear expansion than the quartz tube 24, heated and integrated to form the solid rod material 27. The rod material 27 is then inserted into a quartz tube, heated, integrated, drawn, to give optical fiber consisting of the light waveguide part 31 comprising the core 32 and the clad 33, the strain providing part 34 made of quartz glass, the second clad laye 35 having a higher heat shrinkage ratio than the quartz glass, and the outer covering layer 36. Consequently, the titled optical fiber having the desired polarization characteristics can be obtained with good processability inexpensively.
OKAMURA KOUJI
YUASA MITSUO
