Origin of Loss Increase Induced by Hydrogen and Radiation for GeO2-Doped SiO2 Fibers

Hiroaki HANAFUSA  Yoshinori HIBINO  Hiroki ITOH  Fumio YAMAMOTO  

IEICE TRANSACTIONS (1976-1990)   Vol.E71   No.2   pp.167-173
Publication Date: 1988/02/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Electro-Optics

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The influence of impurities in performs and of the drawing condition on the hydrogen-induced loss increase in the OH absorption band and the radiation-induced loss increase is investigated. The loss increase is much larger in fibers contaminated by sodium. Moreover, the loss increase in fibers with natural SiO2 clad, which is contaminated by alkali ions, increases with increasing maximum temperature in the drawing furnace and with decreasing drawing speed. By thermodynamically analyzing these results, the origin of the loss increase is identified as follows:
(1) The OH loss increase and the radiation-induced loss increase are ascribed to the same origin.
(2) The structural reorientation from GeO4 tetrahedrons to GeO6 groups thermally occurs in the drawing process, when the perform is contaminated by alkali ions.
(3) The loss increase is induced through the reaction of H2 and radiation with GeO6 groups.