POLARIZATION MAINTAINING OPTICAL FIBER AND ITS MANUFACTURING METHOD, AND BASE MATERIAL FOR POLARIZATION MAINTAINING OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To provide a polarization maintaining optical fiber with small transmission loss, and its manufacturing method and a base material for the polarization maintaining optical fiber manufactured by the manufacturing method. SOLUTION: In the manufacturing method for the polarization maintaining optical fiber, an insertion hole is formed in the clad material of the base material of the polarization maintaining optical fiber and its internal surface is polished with abrasives, a polishing tool polishes the internal surface of the insertion hole by rotating in the insertion hole perpendicularly to the length of the base material of the polarization maintaining optical fiber and reciprocating along the length, the rotational frequency of the rotation of the polishing tool is 50 to 200 r.p.m. and the speed of the reciprocation is 10 mm/min to 2 m/min. The base material of the polarization maintaining optical fiber is of <=1.5μm the maximum value and <=1.0μm in the mean value of center-line mean roughness Ra of the internal surface of the insertion hole in terms of JIS K0601. The polarization maintaining optical fiber has a mean presence amount of air bubbles per length of 10 km of <=1.5 and the content of hydroxyl in the core of <=0.0 p.p.m.