  We report on the CEP stabilization of an Yb-doped fiber amplifier system
delivering 30 microjoules, 100 fs pulses at 100 kHz repetition rate. A single
shot, every shot, measurement of the CEP stability based on a simple f-2f
interferometer is performed, yielding a CEP standard deviation of 320 mrad rms
over 1 s. Long-term stability is also assessed, with 380 mrad measured over one
hour. This level of performance is allowed by a hybrid architecture including a
passively CEP-stabilized front-end based on difference frequency generation,
and an active CEP stabilization loop for the fiber amplifier system, acting on
a telecom-grade integrated LiNbO3 phase modulator. These results demonstrate
the full compatibility of Yb-doped high repetition rate laser for attoscience.
