Abstract

Electromagnetically induced transparency (EIT) of three-level atoms in a strong laser pulse¹ is attracting growing interest. We demonstrate here the feasibility of a modulation-induced inhibition of dynamics (MID), self-transparency, and very-high- order frequency mixing (HFM) in a two- level system (TLS) subjected to a periodically modulated laser field. In contrast to self-induced transparency (SIT) in 2π solitons characterized by the dramatic dynamics of population,² in MID the TLS dynamics (i.e., the oscillations of both the population and the polarization) are almost fully suppressed. For a sinusoidal modulation, the conditions for MID coincide with those for the resonances occurring if the frequency of modulation Ω_M is close to a subharmonic of the averaged Rabi frequency $\overline{{\Omega }_R}$.³ It has also been shown⁴ that similar resonances in TLS may occur even when the system is driven by a cw (non- modulated) field strong enough to superdress TLS by having Ω_R exceed the TLS unperturbed frequency ω₀. We showed that at these resonances, in addition to the suppressed population difference δ, the TLS driven polarization p vanishes too, resulting, together with vanishing δ, in the collapse of Rabi sphere. Even when the driving spectral components are strongly off resonance, the field-induced Rabi splitting brings TLS at the MID points into exact resonance with the field. MID results in a self-transparency for the entire spectrum of the incident field (which could be very broad), allowing its propagation without dispersion suppressed now over the spectrum.

© 1995 Optical Society of America