Kilowatt-average-power compression of millijoule pulses in a gas-filled multi-pass cell

In recent years, compression schemes based on distributed spectral broadening in gas-filled multi-pass cells (MPC) have been demonstrated to support millijoule pulse energies [1], [2]. We experimentally demonstrate the scaling of such a MPC to kilowatt average power. A fiber laser source coherently combining 16 amplifier channels provides 1-mJ, 200-fs pulses at a repetition rate of 1 MHz resulting in an average power of μ1 kW [3]. The laser output is compressed by distributed spectral broadening in 26 foci of an Argon-filled MPC and subsequent chirped-mirror compression to 31-fs pulses (see Fig. 1 ) with an average power of 1 kW demonstrating a mirror-reflectivity-limited compression efficiency of >95% [4]. To the best of our knowledge, the MPC output represents the highest average power of sub-100-fs pulses ever demonstrated. Sound characterization of the output in terms of spatio-spectral couplings and beam quality factor reveals a close-to lossless compression [4].