Process for producing optical-fiber base material

Abstract

Provided is a process for producing an optical-fiber base material which can give an optical fiber having a trench type refractive index profile, low transmission loss, low loss of splicing to a standard single-mode optical fiber, and satisfactory flexing resistance. The process is for producing an optical-fiber base material comprising at least a core, a first clad, and a second clad, which contains fluorine. The process is characterized by including: a starting-base-material preparation step in which a starting base material comprising a core and a first clad is prepared; a plasma deposition step in which a raw glass material is fed to a high-frequency induction thermal-plasma torch to synthesize fine glass particles, and the particles are deposited on the base material to produce a porous intermediate glass base material; and a step in which the porous intermediate glass base material is heated and vitrified in a fluorine-containing atmosphere to form an intermediate glass base material which comprises a core, a first clad, and a second clad, which contains fluorine.

Description

Technical field [0001] The invention relates to a method for manufacturing an optical fiber base material using a high-frequency induction thermal plasma torch, in particular to a method for manufacturing a glass base material for a low-OH bend-resistant single-mode optical fiber. In addition, this application is related to the following Japanese application. For designated countries whose recognized documents are incorporated by reference, the contents described in the following applications are incorporated into this application by reference as a part of this application. [0002] Japan Special Application 2008-231373 Application date September 9, 2008. Background technique [0003] In recent years, broadband access such as Fiber To The Home (FTTH) has gradually become popular. In the current house wiring, UTP cables, wireless, etc. are the mainstream, and the pursuit of wider frequency band transmission and direct optical fiber wiring in the office or home are also being studi...

AI Technical Summary

Problems solved by technology

[0033] Although the LWPF used in the main transmission line has the transmission capability near 1385nm, as mentioned above, there is no effective OH group reduction method in the groove type bend-resistant single-mode fiber used in offices, homes, or stations. Therefore, a method of economically manufacturing groove-type bend-resistant single-mode optical fibers with reduced OH groups has been sought

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