  The numerical solution for polarization for two-level atom in polyharmonic
field has been made. The analytical solution for partial case of symmetrical
position of carrier frequency relative to transition frequency is possible. The
results showed that the nonlinear features in polarization spectrum take place
even for small amplitudes of comb-components for small frequency distance
between them. It means that it is necessary to take into account nonlinear
effects for interpretation of spectra in comb spectroscopy.
