Influence of lattice heating time on femtosecond laser-induced strain waves in InSb

Femtosecond laser-induced strain waves in InSb are studied by means of time-resolved x-ray diffraction. The temporal evolution of the measured x-ray diffracted intensity reveals that the lattice dynamics depends on the time scale of energy transfer from excited carriers to the lattice. A framework that accounts for this energy-transfer time (lattice heating time) is presented and applied to model the fluence dependence of the transient x-ray diffraction data. In this model the initial strain wave dynamics depends crucially on the lattice heating time, which decreases with increasing fluence.