  We propose a method of stimulated laser cooling of diatomic molecules by
counter-propagating $\pi$-trains of ultrashort laser pulses. The cooling cycles
occur on the rovibrational transitions inside the same ground electronic
manifold, thus avoiding the common problem of radiative branching in Doppler
cooling of molecules. By matching the frequency comb spectrum of the pulse
trains to spectrum of the R-branch rovibrational transitions we show that
stimulated cooling can be carried out on several rovibrational transitions
simultaneously, thereby increasing number of cooled molecules. The exerted
optical force does not rely on the decay rates in a system and can be orders of
magnitude larger than the typical values of scattering force obtained in
conventional Doppler laser cooling schemes.
