Quantum kinetic approach for spatio-temporal carrier dynamics in femtosecond-laser irradiated materials

A microscopic quantum-kinetic theory based on density matrix approach (using Wigner function representation) is formulated to describe the processes of short pulse laser interaction with materials such as semiconductors accounting for arbitrary spatial inhomogeneities in the excitation conditions and other spatial phenomena such as filamentation of tightly focused femtosecond laser pulses, structural modification and catastrophic optical damage. A system of Boltzmann-Bloch transport equations is established that includes both space and momentum dependence of the electron and hole distribution functions and the polarization. Microscopic electron-phonon and electron-electron scattering terms as well as scattering terms that lead to transitions between valence and conduction bands, i.e. impact ionization and recombination terms, are included explicitly in the equations. The formulated theory describes the spatio-temporal carrier dynamics in inhomogeneously excited materials including the coherent interactions of carriers and the laser light field as well as transport due to spatial gradients and electrostatic forces. (author)