We demonstrate cycle-slip-free electronic control of the carrier-envelope p
hase evolution of few-femtosecond light pulses, optical access to its sub-c
ycle fluctuations and suppression of the amplitude noise of a mode-locked l
aser by phase control. As a result, few-cycle light waveforms can now be sy
nthesized with electric and magnetic fields reproducible to within a known
phase error (< 0.3 rad) and an unprecedentedly low amplitude error (< 3%).
The exploration of phase-sensitive light-matter interactions can be tackled
.