On the initiation of fiber fuse damage in high-power ytterbium-doped fiber lasers

TL;DR

This paper investigates the initiation of fiber fuse damage in high-power ytterbium-doped fiber lasers, revealing defect-induced absorption as the cause and providing methods to evaluate operating temperatures and potential fuse limits.

Contribution

It introduces a 3D heat transfer model to simulate fiber fuse initiation and offers analytical solutions for operating temperature evaluation in fiber lasers.

Findings

Fiber fuse initiation is caused by defect-induced absorption.

Critical temperatures and powers for fuse initiation are simulated.

Operating temperature evaluation methods are provided for specific fiber lasers.

Abstract

Fiber fuse effect can occur spontaneously and propagate along optical fibers to cause wide-spread damage; it threatens all applications involving optical fibers. This paper presents two results. First, it establishes that the initiation of fiber fuse (IFF) in silica fibers is caused by defect-induced absorption. Critical temperatures and critical optical powers for IFF are simulated for the first time using a 3D solid-state heat transfer model with heat source generated by defect-induced absorption. In this method, formation energies of the defects can be uniquely determined, which offers critical information on the chemical reasons for fiber fuse. Second, this paper offers a method to evaluate operating temperatures of fiber lasers. General analytical solutions of the operating temperatures along gain fibers are deduced. Results of 976-nm laser-diode-(LD)-pumped and 1018-nm tandem-pumped ytterbium-doped fiber (YDF) amplifiers using 10/130-{\mu}m YDFs are calculated. Potential limits caused by fiber fuse are discussed.