MOPA laser system with a 4-channel Yb:YAG single-rod amplifier and coherent beam combining

A new architecture of a MOPA laser system with a 4-channel Yb:YAG single-rod amplifier was proposed and brought to life. An average power of 20 W at a pulse energy of 17 mJ was achieved at the system output. A tiled-aperture coherent beam combining with 57% power in the central lobe was demonstrated. A digital controller with feedback enabled efficient suppression of phase fluctuations in channels that were mainly concentrated in the bandwidth up to 10 Hz. The relative standard deviation of residual fluctuations was ∼1%.