Fig. 2
Simultaneous excitation of multiple IR modes. Schematic of the imaginary part of the dielectric function (left axis) with superimposed 300 fs Gaussian pulse (right axis, power spectral density). The horizontal blue lines highlight the positions of the IR modes, which are all polarized along the same crystallographic axis. Even though the pulse is tuned to be resonant with a particular IR mode, because the pulse has a finite width, it will also excite other IR modes that are close in frequency to the target phonon
