Femtosecond light source synchronized with molecular motion

Summary form only given. We have demonstrated that highly coherent molecular motion can modulate light to produce a wide comb of mutually coherent spectral sidebands. The spectrum, which covers several octaves of optical bandwidth, can be used to synthesize periodic trains of shaped pulses, with a theoretical possibility of subfemtosecond and sub-cycle pulse compression. We have used this Raman light source to demonstrate coherent control of multiphoton ionization on a few-femtosecond time scale, under conditions where photoionization requires eleven photons of the lowest frequency and five photons of the highest frequency of the spectrum. Furthermore, we have used the multiphoton ionization process to characterize our light source. Experiment-to-theory comparison implies generation of a single-cycle pulsed structure, with a 2 fs pulse duration.