Spectroscopic signature of phosphate crystallization in Erbium-doped optical fibre preforms

TL;DR

This paper identifies spectroscopic signatures of phosphate crystallization in Erbium-doped silica optical fibre preforms, revealing how phosphorus influences the formation of ErPO4 crystallites and their spectral features.

Contribution

It provides the first spectroscopic evidence of ErPO4 crystallites in phosphorus-doped silica fibres, linking spectral features to crystalline structures.

Findings

Spectroscopic signatures of ErPO4 crystallites identified

Emission and excitation spectra show characteristic features

Crystalline structures influence the optical properties of fibres

Abstract

In rare-earth-doped silica optical fibres, the homogeneous distribution of amplifying ions and part of their spectroscopic properties are usually improved by adding selected elements, such as phosphorus or aluminum, as structural modifier. In erbium ion (Er3+) doped fibres, phosphorus preferentially coordinates to Er3+ ions to form regular cages around it. However, the crystalline structures described in literature never gave particular spectroscopic signature. In this article, we report emission and excitation spectra of Er3+ in a transparent phosphorus-doped silica fibre preform. The observed line features observed at room and low temperature are attributed to ErPO4 crystallites.