100 W, 7 ps hybrid Yb-fiber and Yb:YAG thin-rod MOPA laser

We report a low-cost hybrid Yb-fiber and three-stage Yb:YAG thin-rod MOPA laser pumped by high-brightness LDs, which delivers 100.4 W average power, 7 ps pulses at 20 MHz repetition rate. The all-fiber frontend emits 17 ps, 20 MHz linearly polarized pulses with an average power of 1.5 W. The first stage Yb:YAG thin-rod amplifier is a doublepass amplifier with single end pump. The maximum output power of 20 W was obtained with respect to a pump power of 123 W. The M² measured at 17 W output was 1.39. The second stage is bi-directionally end pumped and the maximum output power was 55.1 W under 112 W and 113 W pump powers in both directions. The slope efficiency is 20%. In the third stage, the signal was single passed and the maximum output power was 100.4 W under 113 W and 120 W pump powers in both directions. The corresponding slope efficiency is 23.4%. The pulse duration was measured to be 7 ps and the optical spectrum is centered at 1032.3 nm with 0.22 nm full-width at half maximum. The M² measured at 91 W was 4.0.