Ultrafast spectroscopy and its application in condensed matter physics

Ultrafast spectroscopy has drawn great interest recently.Among its advantages are ultrahigh time resolution, wide-ranging nonlinear light-matter interactions, coherent control of quantum states, and the possibility of developing many related technologies.We describe its general principles and the technical realization of time-resolved measurements, including the typical geometries. The significance of ultrafast spectroscopy in the study of condensed matter physics is illustrated through various examples.