Femtosecond CPA laser system emitting 261W average power, 1.75mJ pulse energy based on coherent combination of a 49-core fiber

We present a coherently-combined Ytterbium-doped multicore-fiber-based ultrafast laser system emitting up to 261 W average power and 1.75 mJ energy pulses with 330 fs duration at 148 kHz repetition rate. Combination efficiencies of 75% are achieved at the highest average power and pulse energy.