Abstract

For some time now it has been realized how the ultrashort coherence time of long pulsed broadband (incoherent) light (IL) can be used for measuring ultralarge dephasing rate constants. In a recent review¹ three illustrative examples are discussed. Although ultralarge dephasing rate constants can be studied, their measure represents a long time (accumulative) average of the attendant stochastic processes—namely, the time scale of the pulse of incoherent light. This contrasts with measurements using near-transform-limited (coherent) ultrashort light pulses (CLs), where stochastic processes are probed in a nonaccumulated fashion. Thus a given stochastic process might be in a fast modulation limit when using long pulsed IL; it could be in the slow modulation limit when working with short pulses of CL. In contrast to experiments with short pulsed CL, studies with long pulsed IL permit ultrasharp frequency resolution. Other interesting differences exist as well. We just completed a comparative theoretical² and experimental³ study of these two methods for studying dephasing processes. New discoveries include:

© 1990 Optical Society of America