Dispersed ultrafast nonresonant electronic responses: detuning oscillations and near resonance effects

Detuning oscillations, previously observed in the dispersed optical heterodyne detected (OHD) birefringent responses of nonresonant liquids when the pump and probe pulses were temporally overlapped, are shown to be inherent to frequency resolved nonresonant P(3) electronic responses. For a Gaussian pump and a one-sided exponential probe pulse, the frequency of these detuning oscillations is equal to the detuning from the probe carrier frequency. This effect is related to the coherence coupling effects well known in resonant pump–probe studies. These detuning oscillations vanish in the corresponding dispersed SHG cross-correlations and dispersed homodyne responses. The influence of near two-photon resonance is considered.