Abstract

Optical dynamics at ultrafast time scales is mostly studied by time resolved nonlinear optical experiments with ultrashort pulses. The rapid development of techniques to generate almost transform limited pulse durations of well under 10 femtoseconds^[1] has greatly stimulated this line of research. Ultrahigh time resolution can also be obtained with chirped laser pulses as an excitation source. Here, a large bandwidth is combined with phase control during a long non-transform limited pulse. The optical frequency can thus be swept through material resonances in a controlled way. The time resolution is not determined now by the pulse duration but mainly by the chirp rate. In addition, the response of the material shows important qualitative differences between both kind of experiments, which allows for an assessment of the importance of slow fluctuations (inhomogeneous broadening) in a system. This feature was used by us in a study of liquid state optical dynamics.

© 1992 IQEC