  An efficient technique to produce a periodic sequence of ultrashort pulses of
recoilless gamma-radiation via its transmission through the optically thick
vibrating resonant absorber was demonstrated recently [Nature, 508, 80 (2014)].
In this work we extend the theoretical analysis to the case of a set of
multiple absorbers. We consider an analytical model describing the control of
spectral content of a frequency modulated gamma-radiation by selective
correction of amplitudes and initial phases of some spectral components, using,
respectively, the resonant absorption or dispersion of nuclei. On the basis of
the analytical solutions we determine the ultimate possibilities of the
proposed technique.
