Quenching and lasing effects in erbium-doped fibers made with alkaline earth fluoride nanoparticles

Erbium as a dopant in optical fiber is highly valued for its use in lasing and amplification. However, the scalability of erbium-doped fibers (EDFs) has been limited by the natural likelihood of the rare earth ion to cluster in silicate glasses. When the ions cluster, they continuously trade energy with each other, inhibiting the ability for each ion to radiatively deexcite back to the ground state. This process also results in excess heat, which further limits the potential for EDFs to scale to high power without effective cooling. This work investigates a novel approach towards reducing these effects in EDFs. Through the incorporation of both nanoparticle structures and alkaline earth co-dopants, this new fiber takes a multi-directional approach to prevent ions trading energy. Thirteen versions of this aluminosilicate optical fiber were drawn and characterized. Through a combination of both the nanoparticles and alumina contained in the precursor, average erbia densities as high as 2 wt.% are realized. These highly-concentrated EDFs have trackable baria retention rates depending on the amount of alumina used when doping. Theories about controlling mechanisms behind dopant retention rates are discussed. Cross-sections and gain curves for different operation bands related to varying erbium concentration are presented. From these fiber characteristics, modeling of ion bonds and quenching rates are attempted. To demonstrate a reduction in quenching effects despite increased erbium concentration, both quantum and slope efficiencies were measured. Heavily doped fibers with quantum efficiencies up to 0.76 are demonstrated. Slope efficiencies as high as 48% for 976 nm pumping are presented. These efficiencies are compared to commercially available EDFs to demonstrate a proof of concept to reduce erbium ion quenching for modernizing optical fiber lasers. Theories of the contributions from both the solubilizing co-dopants and nanoparticle precursor are discussed. While the understanding of how the nanoparticle structure affects the resultant fiber is unclear, comparing to a control EDF that was made without nanoparticles provides theories towards ion isolation effects.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Campbell, Jennifer Jane

Contributors dc:contributor

• Dragic, Peter
• Goldschmidt, Elizabeth
• Gollin, George
• Ballato, John

• fiber optics
• erbium-doped fiber
• fiber lasers

Statement dc:rights

• Copyright 2025 Jennifer Campbell

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132741

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132741