Special active fiber for high power lasers

With the rapid development of domestic fiber lasers, the output power is constantly improving, resulting that the requirement of active fiber is becoming stricter. YOFC company has proposed a kind of triple cladding active fiber fabrication technology, which combines Plasma Chemical Vapor Deposition (PCVD) platform and Modified Chemical Vapor Deposition (MCVD) platform to make preform which has several characteristics like, large size, high concentration doping, long effective length, high uniformity, Fluorine doped outer cladding and so on. Special fiber drawing technique has been used to match this special preform, finally obtained triple cladding Ytterbium doped fiber (TC YDF) with excellent performance such as, low background loss which is less than 10 dB/km, high doping concentration of rare earth, high uniformity and strong resistance to the photo-darkening; The resonant cavity which consist of this TC YDF can obtained laser power up to 3550w, simultaneously the optical-to optical conversion efficiency is up to 78%, the Raman scattering suppression ratio is larger than 35dB. The fiber laser is continuously monitored for 1500 hours at 3550w, the results show that the output power are nearly stable, which indicates that this TC YDF has an excellent long-term reliability and can be used in industrial processing stably on a large scale.