Watt-level and near diffraction-limited Pr-doped single-crystal fiber lasers.

Using a CZ-grown a-cut Pr:YLF crystal as laser gain medium after processing it into crystal fiber, we have demonstrated real Pr-doped single-crystal fiber lasers for the first time to the best of our knowledge. This Pr crystal fiber has absorbed up to 20.4 W of pump power, which is the highest absorbed power among Pr lasers. For two representative laser emissions at about 639 nm and 607 nm, we have achieved maximum output powers of 5.45 W and 3.04 W, respectively. Output powers of the two lasers show very good linearities, which indicate that the present output powers are only limited by the available pump power. Both laser emissions have exhibited near diffraction-limited beam qualities. This proposal has provided a good and feasible route for the development of compact, high-power, and high-brightness all-solid-state Pr visible lasers via crystal fiber.