A high-power, efficient pulsed amplifier based on a laser diode end-pumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) rod was demonstrated. The crystal’s reabsorption was effectively minimized by optimizing the amplifier’s parameters through numerical simulations, leading to a power extraction efficiency of up to 56%. A compensation method was applied to correct the beam distortion caused by thermally induced birefringence in the Yb:YAG rod. Furthermore, a remarkably low depolarization rate of 2.2% was achieved, along with an average power output of 483 W. The beam quality factor (M2) of the amplified signal was improved to below 1.3, following compensation of the thermally induced spherical aberration using a phase plate. To the best of our knowledge, this achievement represents the highest average power and efficiency for fundamental mode operation in an Yb:YAG rod amplifier at room temperature.
