High-efficiency Yb:YAG thin-disk chirped pulse amplifier delivering 884-femtosecond laser with tunable repetition rates and high stability

We experimentally demonstrated a compact, highly efficient, stable, chirped pulse amplification (CPA) thin-disk regenerative system with a tunable repetition rate. The laser head consists of a 9 at. % Yb:YAG thin-disk with a diameter of 8.8 mm and a thickness of 150 μm, is designed for a 48-pump pass configuration. In CPA-based regenerative amplifier configuration, a maximal output power of 85 W at 500 kHz is achieved with a conversion efficiency of 53.1 %. This corresponds to a pulse energy of 170 μJ. To the best of our knowledge, this is the highest conversion efficiency in CPA thin-disk regenerative amplifiers. The pulse width is compressed to 884 fs with a pair of grating, resulting in a peak power of 192 MW. At 85 W, a near diffraction limit beam quality factor M² of 1.40 is measured, which is essential in precision applications. In addition, remarkable long-term power stability is confirmed with a root-mean-square (RMS) fluctuation of 0.12 % over a 24-hour duration. The reported femtosecond amplifier is believed to be a promising tool for various applications such as extreme manufacturing, terahertz spectroscopy, etc.