FEMTOSECOND TEMPORAL PROBES USING SPECTRALLY TAILORED NOISY QUASI-CW LASER-LIGHT

Theory and experiment are presented that suggest a new avenue for desi gning femtosecond temporal probes in which multiple spatially overlapp ed noisy (nontransform limited) quasi-cw laser light beams are tailore d in a controllable fashion by dispersion. The generation of femtoseco nd probes is demonstrated experimentally by combining the output from two distinct nanosecond pulsed dye lasers to form a single ''tailored' ' beam having a double-peaked spectral density corresponding to the su perposition of emission spectra of each of the dye lasers. The interfe rograms produced from this single beam display features on the time sc ale significantly shorter than the autocorrelation time of either of t he component beams alone. The theory, incorporating controllable dispe rsion effects, correctly captures the interferometric patterns seen in noisy light two-color frequency summing experiments and is general en ough to treat experiments involving the spatially combined emission of an arbitrary number of light sources. Concepts both of noisy light sp ectroscopy and of amplitude modulated pulse shaping are applied. Appli cations of such tailored noisy light sources to wave-packet preparatio n and even photochemical control may be anticipated.