Long-term stabilization of the carrier-envelope phase of few-cycle laser pulses

The temporal variation of the electromagnetic field of a few-cycle laser pulse depends on whether the maximum of the pulse amplitude coincides with that of the wave cycle or not, i.e., it depends on the phase of the field with respect to the pulse envelope. Fixation of this 'carrier-envelope' phase has only very recently become possible for amplified laser pulses. This paved the way for a completely new class of experiments and for coherent control down to the attosecond time scale because it is the field and not the pulse envelope which governs laser-matter interactions. However, this novel technique still affords much potential for optimization. In this paper we demonstrate a novel stabilization scheme for the carrier-envelope phase that not only guarantees a stable phase for arbitrarily long measurements, but also makes it possible to restore any given phase for an application after a pause of any kind. This is achieved by combining a stereo-ATI phase meter with a feedback loop to correct phase drifts inside and outside the laser system.