Mode locking and broadening of the spectrum of a signal at the Stokes frequency due to amplification in the field of a noise-like Gaussian pump wave

It is shown that the use of a narrow-band noise-like Gaussian pump wave in the Raman amplifier makes it possible to perform efficient mode locking at the frequency of the first Stokes component. This locking is accompanied by a considerable broadening of the spectrum of the amplified signal and the signal exhibits pure amplitude modulation. The degree of mode locking and of the broadening of the spectrum is a function of the shape of the correlation function of the pump envelope.