High-average-power 1-μm performance and frequency conversion of a diode-end-pumped Yb:YAG laser

Using a diode-end-pumped technology, a Yb:YAG laser capable of delivering up to 434 W of CW power has been demonstrated. The system incorporates a unique composite rod design which allows for high-average-power operation while simultaneously suppressing parasitic oscillations. Modeling and experimental data to support the quenching of parasitics are discussed. Beam quality measurements for CW operation with several cavity configurations are presented. In particular, beam quality measurements at 340-W CW yielded a beam quality factor of M²=21. Predictions of a quasi-three-level model are compared with the experimental data for several output coupler reflectivities. An observed dependence of the cavity mode fill as a function of output coupler reflectivity is discussed. Employing a single acoustooptical switch, the system was Q-switched at 10 kHz and generated output powers up to 280 W with a measured beam quality of M²=6.8 at 212 W, With an external dual-KTP crystal configuration, the Q-switched output was frequency converted to 515 nm and produced up to 76 W at 10 kHz in a 30-ns pulse length