Influence of core codopants and components on laser properties of high-power holmium-doped silica all-fiber lasers

We demonstrate and analyze the performance of a continuous all-fiber laser delivering up to 180W at 2.12μm in a single spatial mode, with an optimum optical efficiency of 60%, based on a triple clad holmium doped fiber. For this laser we realized several holmium doped fibers, with a core either based on alumina-silica and surrounded with a pedestal, or on alumino-phospho-silica. We thus compare the results obtained with these fibers, and analyze them with our numerical simulation. We also present our efforts to realize a truly all-fiber architecture, comprising an all-fiber pump laser, a pump combiner, fiber Bragg gratings (for an oscillator configuration) and an end-cap, so we will present numerically and experimentally how these components affect the performance of a high power laser, in terms of optical efficiency or spatial beam quality.