The influence of phase-modulation on femtosecond time-resolved coherent Raman spectroscopy

The influence of phase-modulation on femtosecond time-resolved
coherent Raman scattering is investigated theoretically and
experimentally. The coherent Raman signal taken as a function of
the spectral position shows unexpected temporal oscillations close
to time zero. A theoretical analysis of the coherent Raman
scattering process indicates that the femtosecond light pulses are
amplitude and phase modulated. The pulses are asymmetric in time
with more slowly decaying trailing wings. The phase of the pulse
amplitude contains quadratic and higher-order contributions.