PURPOSE: To obtain a radiation resistant optical fiber with a small intrinsic loss by irradiating SiO2 or SiO2-GeO2 soot with radiation or ultraviolet rays and introducing many OD groups into the soot.
CONSTITUTION: SiO2 or SiO2-GeO2 soot 10 obtd. by a VAD method as a starting material for an optical fiber is put in the core tube 12a of a furnace 12 for converting soot into transparent glass, and many structural defects are produced in the fine glass particles of the soot 10 by γ-rays emitted from a γ-ray source 16 shielded by a lead shielding pipe 14 in the furnace 12. Since D (deuterium) and He have been introduced into the tube 12a, D is captured in the structural defects and reacts with Si, so OD groups are introduced into the glass. Radiation such as X-rays or electron beams or ultra-violet rays may be used in place of said γ-rays. The soot is converted into transparent glass immediately after irradiation. The irradiated soot may be allowed to stand for several hours before introducing D. At this time, the amount of D that can be doped is reduced.
ORIMO KATSUMI
YOSHIDA KAZUAKI
NISHIMURA MASAO
NAKAHARA MOTOHIRO
INATSUNE NOBUO
NIPPON TELEGRAPH & TELEPHONE
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