  We present the state of the art of a compact high-energy mid-infrared laser
system for TW-level 8-cycle pulses at 7 um. This system consists of an
Er:Tm:Ho:fiber MOPA which serves as the seeder for a ZGP-based OPCPA chain in
addition to a Ho:YLF amplifier which is Tm:fiber pumped. Featuring all-optical
synchronization, the system delivers 260-mJ pump energy at 2052 nm, 16-ps
duration at 100 Hz with a stability of 0.8 % rms over 20 min. We show that
chirp inversion in the OPCPA chain leads to excellent energy extraction and
aids in compression of the 7-um pulses to 8 optical cycles (188 fs) in bulk
BaF2 with 93.5 % efficiency. Using 21.7 mJ of the available pump energy, we
generate 0.75-mJ-energy pulses at 7 um due to increased efficiency with a
chirp-inversion scheme. The pulse quality of the system's output is shown by
generating high harmonics in ZnSe which span up to harmonic order 13 with
excellent contrast. The combination of the passive carrier-envelope phase
stable mid-infrared seed pulses and the high-energy 2052 nm picosecond pulses
makes this compact system a key enabling tool for the next generation of
studies on extreme photonics, strong field physics and table-top coherent X-ray
science.
