Spectrum of high harmonics generated by two-color circularly polarized laser field in atomic media

Here we discuss the new effects in the light-atom interaction of an atom and two-colour (omega, 2 omega) elliptically polarized femtosecond pump beams. We show that the spectrum of atomic response does not include the signal at summary frequency (omega+ 2 omega) and its harmonics when the frequency components of the pumping field are counter-rotating and the atom is ins-ground state. In the case when the ground state of the atom isp-state (l= 1), these components vanish in the response spectrum of the longitudinal atomic current. In both cases, the suppression of the summary frequency is accompanied by the suppression of signal at THz frequency.