Coherent transients as a highly sensitive probe for femtosecond pulse shapers

We report on the application of shaped femtosecond pulses on low-field chirped excitation of an atomic two-level system. The induced transient phenomena can be considered as a phase diagram of the excitation pulse. Their high sensitivity to the phase-modulated pulse is analyzed, by comparing numerical solutions of the time-dependent Schrödinger equation with experimental results. These coherent transients allow for high precision calibration of pulse-shaping setups where usual methods are less efficient. As an illustration, a comparison between 128-pixel and 640-pixel spatial light modulator pulse shapers is given. PACS 32.80.Qk; 42.50.Md; 42.65.Re; 82.53.KpThis revised version was published with corrections to the e-mail address of the corresponding author, to Fig. 1, to a typo in page 4: sensitivity instead of sensivity, and to the references, which now have all authors listed.