Ytterbium doped fibers without photodarkening

ProjectPhotodarkening in Yb glass

Labs & TestbedsAcreo Fiberlab
Photodarkening in Yb glass

Fiber lasers are known to suffer from induced optical losses at visible and lasing wavelengths (near 1.1µm), when operated at high powers. The phenomenon is commonly called photodarkening.

Photodarkening can typically reduce the output power of a fiber laser with about 10% over 1000 hours.

Acreo and NKT Photonics (Crystal Fibre) carried out a joint research project to determine the nature of photodarkening, and on a longer perspective minimize the effect by optimizing fiber design and material composition.

The project was concluded in May 2008 when the PhD student Magnus Engholm presented his thesis at Mid Sweden University. Several mechanisms related to the formation of induced color centers were identified, which has paved the way to more efficient and power tolerant glasses.

Please refer to the publications for project results. 

The company Raybium AB was started in 2010 by the PhD student carrying out the research. 

About the project

Project objective: To explain the mechanisms behind photodarkening and to provide tools for designing improved laser glasses.
Project leader: Acreo.
Project members: Acreo, NKT Photonics.
Project sponsors: Acreo, NKT Academy, Länsstyrelsen i Gävleborg, Mål2 Norra, Fiber Optic Valley.
Acreo contact: Lars Norin, lars.norin [at], ph: +46 650 366 14.