Fabrication Method For Lma Multi-Clad Yb-Doped Silica Pm Fibers

The fabrication of a polarization-maintaining version of a large-mode-area multi-clad fiber design with high Yb concentrations and a robust output beam represents a significant challenge due to the high risk of cracking of the doped silica multi-clad next to the core during the drilling procedure. A new preform fabrication approach permitting the realization of a large first-clad fiber featuring a high birefringence, while preserving the preform integrity is presented. The birefringence was improved by locating the stress-applying-parts in the first-clad region and by increasing their boron content. The preform and fiber fabrication will be presented as well as the fiber performances in a pulsed amplifier configuration.