High power all-fiberized laser oscillator employing novel constant-cladding tapered-core Yb-doped fiber

In this work, we have proposed and fabricated a novel constant-cladding tapered-core (CCTC) Yb-doped fiber, which has a constant cladding diameter of ~600 μm and spindle-shaped core diameter with a ~20.8 μm at both ends and ~36.0 μm in the middle. Based on this CCTC fiber, an all-fiberized laser oscillator was constructed and investigated experimentally. The output power was scaled to 1514 W with an optical-to-optical efficiency of ~64%, and the measured beam quality (M2 factor) is ~1.6. The further power scaling is promising by optimizing the structure of the CCTC fiber.