1. Zoran Ivić, University of Belgrade, Vinča Institute of Nuclear Sciences, Serbia, Serbia
We study the effects of dispersion in carrier waves on the properties of self–induced transparency (SIT) in
two-level media. The substantial impact of dispersion effects on typical SIT soliton features is predicted. For
example, the degree of SIT pulse velocity slowing down (acceleration) is determined by the ratio of an incoming
pulse frequency over atomic transition frequency – x = !=!0. Specifically, in the sharp–line limit an immediate
pulse stopping is predicted for absorbing media when both frequency ratio and pulse duration time exceeds some
critical values. In the amplifying media, superluminal motion is predicted as in the case of resonance. However,
there exists the lowest value in the frequency ratio below which the pulse velocity tends to the subluminal region.
In the inhomogeneously broadened media dispersion curve (K(x)), both for absorbing and amplifying media,
exhibits gradual increase as function frequency ratio, approaching linear law for large x. On the other side,
velocity delay vs normalized pulse width exhibits similar behavior as well as in the sharp–line limit. That is,
in the absorbing media, near the resonance (x & 1), velocity slowly decays as pulse width increases. On the
other hand, for x < 1, and for short pulses, superluminal motion is predicted. This is an unphysical result and
should be disregarded. In the amplifying media meaningful results, superluminal velocity, exist only in and
above the resonance x = 1. An interesting behavior of the Ber’s absorption coefficient is predicted: it, both in
the absorbing and amplifying media, gradually decay as a function of frequency ratio, implying the enhanced
transparency in the near resonance region. New ways for the controlling of propagation of the electromagnetic
waves in a two-level media can be developed by exploiting these new features of the SIT phenomena. This may
be achieved by varying frequency ratio. A possible way of practical realization is the design of devices based
on quantum metamaterials with tunability in their parameters.
Key words :
Thematic field:
SIMPOZIJUM A - Nauka materije, kondenzovane materije i fizika čvrstog stanja
Date:
01.08.2020.
Contemporary Materials 2020 - Savremeni materijali
