Abstract

In transient spectroscopy, the time-resolution is usually limited by the pulse width or the risetime of light sources or equivalent perturbers. In the extremely short time region, however, its improvement by shortening the pulse width is not an easy way even with the recent development of femtosecond pulse technique. We propose here a new method of transient spectroscopy were the time resolution is not limited by the light duration t_p but limited only by the correlation time τ_c of light sources, being generally much shorter than t_p. A temporally incoherent light has a short τ_c corresponding to the reciprocal bandwidth, and appears like a single pulse of duration τ_c in the auto-correlation measurement. This kind of light is therefore expected to play essentially the same role as a short pulse in nonlinear spectroscopy utilizing the auto-correlation technique. We present here a basic theory and an experiment which confirm this idea.

© 1984 Optical Society of America