The Journal of Chemical Physics
Wigner spectrogram representations of heterodyne-detected four-wave-mixing and fluorescence up-conversion
Shaul Mukamel
Abstract
Gated spontaneous emission and four-wave-mixing signals are expressed using a mixed time-frequency representation of the fields (Wigner spectrograms) and of the material response functions. Well-separated and overlapping pulses are described using two-sided (noncausal) and one-sided (causal) spectrograms, respectively. Pump–probe and fluorescence spectra are recast in an anologous form which facilitates the direct comparison of the underlying microscopic dynamics.