This paper describes novel time-domain multiplexing techniques that use various resonant cavity configurations for increasing pulse energy extraction per each parallel amplification channel of a coherently combined array. Two different techniques are presented: a so-called N2 coherent array combining technique, applicable to a periodic pulse train, and a coherent pulse stacking amplification (CPSA) technique, applicable to a pulse burst. The first technique is a coherent combining technique, which achieves simultaneous beam combining and time-domain pulse multiplexing/down-counting using traveling-wave Fabry-Perot type resonators. The second technique is purely a time-domain pulse multiplexing technique, used with either a single amplifier or an amplifier array, which uses traveling-wave Gires-Tourmois type resonators. The importance of these techniques is that they can enable stacking of very large number of pulses, thus increasing effective amplified-pulse duration potentially by 102 to 103 times, and reducing fiber array size by the corresponding factor. This could lead to very compact coherently combined arrays even for generating very high pulse energies in the range of 1 to 100 J.

Thin-film compression (TFC) and the focusability of high-power laser pulses after self-phase modulation in thin films at transport intensities (∼1 TW∕cm 2 ) for petawatt laser systems is demonstrated. High-energy (∼296 mJ) laser pulses are compressed from ∼55 fs to ∼31 fs. Additionally, the focusability of high-power (∼45–55 TW) flat-top laser pulses after spectral broadening in thin films is found to be largely maintained, showing only modest decreases in the energy contained in the central part of the focal spot. In light of these findings, TFC offers a method for moving toward single-cycle pulse durations at significantly higher energies than those found at present, and if beam instabilities can be mitigated, maybe even higher intensities.