PURPOSE: To manufacture an optical fiber drawable to a long size and having a small loss and superior polarizing characteristics by making the intermediate parts of base materials for applying stress different from the incident and emergent parts of the base materials in refractive index when the base materials are arranged around a base material for a core and drawn in a jacket.
CONSTITUTION: Base materials for applying stress are manufactured by an MCVD method, and they are composed of base materials 22, 23 made of B2O3. SiO2 for incident parts, base materials 26, 27 made of B2O3.SiO2 for emergent parts and base materials 24, 25 made of GeO2.SiO2 for intermediate parts. The base materials for applying stress are drawn together with a synthetic core-clad base material 21 in a jacket pipe 28. In order to obtain a fiber having ≥about 20km length, the base material 21 for a core is required to have about 1.2mm core diameter, about 10mm clad diameter and ≥ about 60cm length, and the base materials for applying stress arranged around the base material 21 and the jacket pipe 28 are required to have ≥ about 60cm length each.
MIYA TETSUO
KAWACHI MASAO
OKAMOTO KATSUNARI
EDAHIRO TAKAO
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