25 W continuous-wave Yb:LiLuF4 single-crystal-fiber laser oscillator

We present the first demonstration of a solid-state laser oscillator based on a Yb-doped, birefringent single crystal fiber grown by the micro-pulling-down method. Pumping a 42-mm-long, 2%-at Yb3+:LiLuF4 crystal with a 105-W maximum power fiber coupled laser diode, we obtained a maximum output power of 10.4 W, with diffraction limited beam quality (M-2 < 1.1), in a simple plane-concave resonator. By modifying the resonator layout to increase the laser efficiency, we obtained output power up to 25 W, with still fairly good beam quality (M-2 similar or equal to 2). Thermal lensing effect and laser intrinsic slope efficiency and losses were characterized in both resonator configurations.

Automated summary

This study demonstrates a solid-state laser oscillator based on a Yb-doped birefringent single crystal fiber, achieving high output power and good beam quality. By optimizing the resonator layout, researchers obtained a maximum output power of 10.4 W in a simple resonator and up to 25 W in an improved resonator configuration. The thermal lensing effect, laser intrinsic slope efficiency, and losses were characterized in both resonator setups.