Investigation of erbium dopant distribution in silica optical fibers with fluorescence-based measurements using a near-field scanning microscope

Abstract

Abstract. High spatial resolution information of the rare-earth dopant distribution in optical fibers enriches our understanding of the fiber manufacture processes and enables improvement in the design of active photonic devices including optical fiber lasers and amplifiers. Here, data from an investigation of the backscattered fluorescence signal off the end-face of an erbium (Er 3þ ) doped silica optical fiber obtained with a near-field scanning optical microscope (NSOM) are presented. It has been recently confirmed via a theoretical model that information about the relative Er 3þ ion distribution in fibers can be inferred by simply monitoring the fluorescence signal originating from the de-excitation of specific energy levels in the investigated samples. A comparison of the Er 3þ ion distribution profiles extracted from the fluorescence measurements acquired through the NSOM system with those obtained from the application of a powerful analytical ion probe is also presented.

Contributed Review: A review of the investigation of rare-earth dopant profiles in optical fibers

“…38 As a result, NSOM studies of Er doped optical fibers were attempted by monitoring the backscattered fluorescence signal originating from the de-excitation of the 4 S 3/2 energy level, 38 which has been found to be independent of possible interionic effects. [37][38][39] It was recently also shown 43 that initial concerns regarding practical limitations such as weak fluorescence signal and stray light contaminations can be overcome and that good qualitative agreement can be established on data acquired from different techniques (Fig. 2).…”