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

Abstract

We demonstrate the reliable generation of 1-mJ, 31-fs pulses with an average power of 1 kW by postcompression of 200-fs pulses from a coherently combined Yb:fiber laser system in an argon-filled Herriotttype multi-pass cell with an overall compression efficiency of 96%. We also analyze the output beam, revealing essentially no spatio-spectral couplings or beam quality loss.

Multipass cell for high-power few-cycle compression

“…Evaluating the overlap of the offaxis spectra with the on-axis spectrum as defined in Ref. [29] yields an effective homogeneity of 97.5%, proving that no significant degradation occurred with respect to the input [18]. This measurement is a lower-bound estimate as the result is limited by the low signal-to-noise-ratio for wavelengths larger than 1.1 µm.…”

“…An alternative could be nonlinear compression in multipass cells [14][15][16], which recently has been demonstrated at 112 mJ pulse energy [17] and at 1 kW average output power [18]. These cells feature an excellent transmission of up to 96% [18] and a high resilience to beam quality imperfections and pointing instabilities due to their extended free aperture, which allows for straightforward power scaling.…”

“…An alternative could be nonlinear compression in multipass cells [14][15][16], which recently has been demonstrated at 112 mJ pulse energy [17] and at 1 kW average output power [18]. These cells feature an excellent transmission of up to 96% [18] and a high resilience to beam quality imperfections and pointing instabilities due to their extended free aperture, which allows for straightforward power scaling. Hence, these cells were ideal candidates for high-power nonlinear pulse compression to the few-cycle regime, if not the reflection bandwidth of the typical dielectric mirrors used would limit the pulse duration to about 30 fs.…”

“…The laser emits pulses at 500 kHz repetition rate with approximately 1 mJ pulse energy and 200 fs pulse duration. Nonlinear spectral broadening in a first, argon-filled, dielectricmirror Herriott cell and chirped-mirror compression reduces the pulse duration to 31 fs [18]. After this stage, the collimated beam features a 1/e 2 -diameter of 8 mm and an average power of 474 W. The beam continues into a second multipass cell comprising 13 individual 1"-diameter, dielectrically enhanced silver-coated silicon mirrors (RM>98.5%, |GDD|<10fs 2 , 800-1300 nm).…”

High-energy bow tie multi-pass cells for nonlinear spectral broadening applications

“…Recently, a new method based on nonlinear spectral broadening within multi-pass cells (MPC) was introduced [11,12]. The method offers high transmission [13,14], high-power handling [14,15], excellent beam quality [13,16] and large compression ratios [16,17] while being easily adaptable to a large variety of laser pulse parameters including durations ranging currently from 10 ps [18] to few-cycles [17,19,20] as well as pulse energies ranging from a few µJ [21] to more than 100 mJ [22].…”