Thermal behavior of NIR active centers in Bi-doped optical fibers

TL;DR

This study investigates the temperature-dependent optical properties of Bi-doped silica and germanosilicate fibers, revealing differences in ion distribution and identifying NIR-active centers linked to low oxidation states of bismuth.

Contribution

It provides the first measurements of temperature effects on optical loss and luminescence spectra in these fibers, and clarifies the nature of NIR-active bismuth centers.

Findings

NIR-active centers are associated with low oxidation state bismuth.

Distribution of Bi3+ ions differs significantly from NIR-active centers.

Luminescence lifetime of Si-associated centers varies with temperature.

Abstract

The temperature dependences of optical loss and luminescence spectra have been measured in visible and NIR spectral range for Bi-doped silica and Bi-doped germanosilicate fibers for the first time. The temperature dependence of luminescence lifetime for Si-associated active bismuth centers in germanosilicate fiber was measured. It has been revealed, that distribution of Bi3+ ions across the fiber preform is essentially different as compared to that of NIR active bismuth centers. Data received indicates that NIR-active centers are associated with the low oxidation state of bismuth ion and/or oxygen deficient center of the glass structure.