A novel method for measuring the resonant absorption coefficient of rare-earth-doped optical fibers

TL;DR

This paper introduces a non-destructive, accurate method for measuring the resonant absorption coefficient of rare-earth-doped optical fibers by comparing spontaneous emission at two points, avoiding damage and inaccuracies of previous techniques.

Contribution

The paper presents a novel, non-invasive technique for measuring absorption in optical fibers that is applicable to various designs and more accurate than existing methods.

Findings

The method accurately measures absorption coefficients across different fiber types.

It outperforms the cut-back method in precision and safety.

It is suitable for fragile optical fibers due to no mechanical movement.

Abstract

A non-destructive method for measuring the resonant absorption coefficient of rare-earth-doped optical fibers is introduced. It can be applied to a broad range of fiber designs and host materials. The method compares the side-collected spontaneous emission at two arbitrary locations along the fiber as a function of the pump wavelength to extract the absorption coefficient. It provides an attractive and accurate alternative to other available techniques. In particular, the proposed method is superior to the cut-back method, which destroys the sample and is prone to inaccuracies due to the cladding mode contamination. Moreover, because it does not involve any mechanical movement, it can be used for fragile optical fibers.