High efficiency of a holmium doped fibre laser in clad-pump configuration

Abstract

We recently developed a holmium-doped triple-clad fiber (Ho-3CF) for laser emission beyond 2.1 μm. In a clad-pumped fiber laser oscillator emitting at 2.12 μm, we obtained an optical efficiency of 73% with respect to the absorbed pump power at 1.94 μm, and a maximum signal power of 62 W. We present here the comparison between the laser measurements and a numerical simulation, together with the measurements of the required physical parameters (crosssections, attenuations…). The alumino-silicate core composition of our initial Ho-3CF samples required the introduction of a pedestal to preserve the single spatial-mode guiding. We also present our preliminary results on a new aluminophospho-silicate core composition, in order to suppress the initial pedestal and simplify the fabrication process. Both samples were also analyzed in core-pumped laser configuration.