High Power Diode Pumped Rare Earth Doped ZBLAN Visible Fiber Lasers: Technologies, Challenges and Opportunities
Oxxius ZBLAN visible fiber laser research today
Presented at the Specialty Optical Fibers conference in 2024, this invited paper by Thierry Georges provides a state-of-the-art overview of high-power ZBLAN visible fiber lasers based on rare-earth-doped fluoride fibers — covering the technologies, current challenges, and opportunities for reaching watt-class visible output from compact, diode-pumped architectures.
Fluoride fiber lasers occupy a unique position in the visible laser landscape. Unlike silica fibers, ZBLAN (ZrF₄-BaF₂-LaF₃-AlF₃-NaF) glass supports rare-earth transitions across the entire visible spectrum — from blue-green (Pr³⁺ at 492 nm and 521 nm) through yellow (Dy³⁺ at 575 nm), orange (Pr³⁺ at 604 nm), red (Pr³⁺ at 635 nm and 698 nm), and deep red (Pr³⁺ at 717 nm) — all pumped by GaN blue diodes. This makes ZBLAN fiber lasers the only all-fiber technology capable of addressing the full visible spectrum from a single fiber platform.
Breakthroughs and remaining challenges
The past five years have seen significant advances in ZBLAN fiber laser performance, driven in part by the availability of higher-brightness GaN diodes and improved fiber fabrication. Watt-class output has been demonstrated at several visible wavelengths, including the 634.5 nm and 717 nm results published in companion Oxxius papers. However, key challenges remain: fiber photodarkening at high UV and blue flux levels, pump coupling efficiency into small double-clad cores, and thermal management at watt-level powers all limit further scaling. This 2024 review paper maps the current state of the field and identifies the most promising technical paths forward.
Oxxius’s role in this ecosystem is dual: as a developer of GaN-pumped visible fiber laser sources through collaborative R&D, and as a manufacturer of the high-brightness blue diode pump modules that enable this class of fiber lasers. The LBX-series at 443 nm and 452 nm provides the pump brightness required to reach threshold efficiently in Pr³⁺:ZBLAN double-clad fiber geometries.
Abstract
Fluoride fiber lasers are promising candidates for high power visible laser generation. Recent breakthrough and means to overcome current limitations will be presented.