Abstract

Phase relaxation of optical excitations in condensed matter can be studied by coherent four—wave—mixing experiments in the time domain without requiring assumptions on the spectral properties of the material. For inhomogeneously broadened transitions, three laser pulses at times t = 0, t = t₂₁ and t = T with wave vectors k₁, k₂ and k₃, respectively, generate a stimulated photon echo pulse, emitted time—delayed at t = T+t₂₁ in the momentum—matching direction according to k₃+k₂−k₁. As a function of t₂₁ the echo amplitude decays due to scattering events, described by the dephasing time constant T₂ [1].

© 1990 Optical Society of America