Mechanisms of optical losses in Bi:SiO2 glass fibers

The mechanisms of optical losses in bismuth-doped silica glass (Bi:SiO(2)) and fibers were studied. It was found that in the fibers of this composition the up-conversion processes occur even at bismuth concentrations lower than 0.02 at.%. Bi:SiO(2) core holey fiber drawn under oxidizing conditions w...

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Bibliographic Details
Published in:Optics express 2012-10, Vol.20 (21), p.23186-23200
Main Authors: Zlenko, Alexander S, Mashinsky, Valery M, Iskhakova, Ludmila D, Semjonov, Sergey L, Koltashev, Vasiliy V, Karatun, Nikita M, Dianov, Evgeny M
Format: Article
Language:English
Subjects:
Bismuth - chemistry
Glass - chemistry
Infrared Rays
Light
Metal Nanoparticles - chemistry
Optical Fibers
Scattering, Radiation
Silicon Dioxide - chemistry
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Summary:The mechanisms of optical losses in bismuth-doped silica glass (Bi:SiO(2)) and fibers were studied. It was found that in the fibers of this composition the up-conversion processes occur even at bismuth concentrations lower than 0.02 at.%. Bi:SiO(2) core holey fiber drawn under oxidizing conditions was investigated. The absorption spectrum of this fiber has no bands of the bismuth infrared active center. Annealing of this fiber under reducing conditions leads to the formation of the IR absorption bands of the bismuth active center (BAC) and to the simultaneous growth of background losses. Under the realized annealing conditions (argon atmosphere, T(max) = 1100°C, duration 30 min) the BAC concentration reaches its maximum and begins to decrease in the process of excessive Bi reduction, while the background losses only increase. It was shown that the cause of these background losses is the absorption of light by nanoparticles of metallic bismuth formed in bismuth-doped glasses as a result of reduction of a part of the bismuth ions to Bi(0) and their following aggregation. The growth of background losses occurs owing to the increase of the concentration and the size of the metallic bismuth nanoparticles.
ISSN:1094-4087
DOI:10.1364/OE.20.023186