PREFORM FOR SINGLE MODE OPTICAL FIBER, SINGLE MODE OPTICAL FIBER AND THEIR PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain a preform for a single mode optical fiber and a single mode optical fiber most suitable for a long distance transmission having a suppressed light loss, etc., by reducing a polarization mode dispersion(PMD) and to readily produce them at a low cost. SOLUTION: This preform for a single mode optical fiber comprises a core at the central part and a clad concentrically enclosing the core, has <=2% ellipticity of the core and <=2% ellipticity of the clad. This single mode optical fiber is produced by heating, melting and drawing the preform and has <=0.1 ps/km0.5 polarization mode dispersion(PMD).