High-efficiency and high-brightness circular-clad, large-size, rectangular core crystalline waveguide Yb:YAG laser

We report what we believe to be a novel circular-clad large-size rectangular core crystalline waveguide Yb:YAG laser. The waveguide has a rectangular core of Yb:YAG with 400 × 400 μm² and a thin rod-shaped cladding of Er:YAG with a diameter of 1.2 mm and a length of 65 mm. The circular-clad structure has improved the pump absorption efficiency of the waveguide. A concave-convex cavity is designed to overcome the power limitation of thermal lens effect on the large-size rectangular core single-mode waveguide. A waveguide oscillator obtains a 1030 nm laser with an average power of 110 W and a beam quality factor of M_x²×M_y² = 1.07 × 1.05, with optical-optical efficiency and slope efficiency of 54% and 67%, respectively. The laser performance is attributed to the double-clad structure and the good thermal management. The results confirm that the waveguide has high potential in power expansion and pulse laser amplification.