Time-resolved two-beam coupling in silicon

The analytical solution of the optical field equations and the material equations for two-beam coupling in a medium with real excitation of quasiparticles is given. Transient energy transfer is analyzed throughout the range of the coherent overlapping of the excitation and probe pulses for a hypothetical medium with variable relation between the real part and the imaginary part of the nonlinear response. A detailed comparison between the theory and the model experiments for two-beam coupling in silicon is given.