Systematic investigation of composition effects on the radiation-induced attenuation mechanisms of aluminosilicate, Yb-doped silicate, Yb- and Yb,Ce-doped aluminosilicate fiber preforms [Invited

Franck Mady,Angela Guttilla,Mourad Benabdesselam,Wilfried Blanc

doi:10.1364/ome.9.002466

Abstract

We present an original experimental approach to the investigation of radiation-induced attenuation (RIA) mechanisms in optical fiber preforms. This protocol combines thermally stimulated luminescence (TSL) measurements with the characterization of RIA annealing during TSL readouts. It is systematically applied to compositions of increasing complexity to resolve the specific role played by each dopant. Silicate, aluminosilicate, Yb-doped silicate, Yb-doped and Yb,Ce-codoped aluminosilicate preform samples are examined. Annealing processes are described in detail as a function of temperature throughout TSL readouts. The protocol reveals the temperature ranges at which trapped-carrier states forming intrinsic or dopant-related color centers are released, thus enabling the assessment of their activation energies. Metastable Ce2+ ions are proved to be formed by electron trapping under irradiation. Along with the formation of Ce3++, they play a crucial role in the RIA mitigation.

Highlights

The optical fiber technology has permitted to design high-power fiber laser sources [1,2] and offered novel metrological opportunities for the distributed sensing of temperature, pressure, strain or radiation doses [3]
The color centers (CCs) formation is due to ionizing radiations and it results into the so-called radiation-induced attenuation or RIA
Since this study aims at investigating the RIA mechanisms in terms of formation and annealing of CCs, it focuses on the characterization of the RIA that develops in the VIS and near UV ranges

Summary

Introduction

The optical fiber technology has permitted to design high-power fiber laser sources [1,2] and offered novel metrological opportunities for the distributed sensing of temperature, pressure, strain or radiation doses [3] Both application fields have to deal with the formation of silica- or dopant-related color centers (CCs) which cause excess optical losses from the ultraviolet-visible (UV-VIS) down to the near-infrared (NIR) optical ranges. Optical (PD loss or RIA monitoring, fluorescence) and ESR measurements are of crucial interest to follow the CCs evolution with temperature, dose, pumping or annealing time Their ability to provide an overview of the mechanisms is though limited, even if correlations between pairs of radiation-induced centers could be highlighted [12,17]. Efforts made at modeling PD and RIA relied on kinetic equations including phenomenological parameters, not on an in-depth description of key physical processes [18,19]

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Conclusion