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Energetic sub-2-cycle laser with 220 W average power

Few-cycle lasers are essential for many research areas such as attosecond physics that promises to address fundamental questions in science and technology. Therefore, further advancements are connected to significant progress in the underlying laser technology. Here, two-stage nonlinear compression of a 660 W femtosecond fiber laser system is utilized to achieve unprecedented average power levels of energetic ultrashort or even few-cycle laser pulses. In a first compression step 408 W, 320 uJ, 30fs pulses are achieved, which can be further compressed to 216 W, 170 uJ, 6.3 fs pulses in a second compression stage. This is the highest average power few-cycle laser system presented so far. It is expected to significantly advance the fields of high harmonic generation and attosecond science.