  The pulse-energy scaling technique electro-optically controlled divided-pulse
amplification is implemented in a high-power ultrafast fiber laser system based
on coherent beam combination. A fiber-integrated front end and a multi-pass
cell based back end allow for a small footprint and a modular implementation.
Bursts of 8 pulses are amplified parallel in up to 12 ytterbium-doped
large-pitch fiber amplifiers. Subsequent spatio-temporal coherent combination
of the 96 total amplified pulse replicas to a single pulse results in a pulse
energy of 23 mJ at an average power of 674 W, compressible to a pulse duration
of 235 fs. To the best of our knowledge, this is the highest pulse energy ever
accomplished with a fiber CPA system.
