Optical response of organic laser-dyes is often discussed considering unfortunately only two electronic energy levels. In the simplest case, the excited state potential surface is displaced along a number of normal coordinates. Vibrations involved in optical dynamics appear as resonance and are also Raman active. A single spectral density suffices to describe optical two-level dynamics of rigid molecules. The high frequency part is hardly distinguishable from the resonance Raman spectrum including proper conversion factors. The low frequency part is difficult to measure by Raman spectroscopy, so femtosecond pump-probe and stimulated photon echo systems are better for structure elucidation.