34,861 research outputs found
Controlled absorption and all-optical diode action due to collisions of self-induced transparency solitons
We study inelastic collisions of counter-propagating self-induced
transparency solitons in a homogeneously broadened two-level medium. The energy
of the pulse can be almost totally absorbed in the medium due to asymmetric
collision with a properly chosen control pulse. The medium state thus prepared
demonstrates the property of an all-optical diode which transmits pulses from
one direction and blocks from another. The saturation process of a controlled
absorption effect, local-field correction influence, and the parameter ranges
for the diode action are studied as well.Comment: 7 pages, 9 figure
Propagation of two short laser pulse trains in a -type three-level medium under conditions of electromagnetically induced transparency
We investigate the dynamics of a pair of short laser pulse trains propagating
in a medium consisting of three-level -type atoms by numerically
solving the Maxwell-Schr\"odinger equations for atoms and fields. By performing
propagation calculations with different parameters, under conditions of
electromagnetically induced transparency, we compare the propagation dynamics
by a single pair of probe and coupling laser pulses and by probe and coupling
laser pulse trains. We discuss the influence of the coupling pulse area, number
of pulses, and detunings on the probe laser propagation and realization of
electromagnetically induced transparency conditions, as well on the formation
of a dark state
Completely integrable models of non-linear optics
The models of the non-linear optics in which solitons were appeared are
considered. These models are of paramount importance in studies of non-linear
wave phenomena. The classical examples of phenomena of this kind are the
self-focusing, self-induced transparency, and parametric interaction of three
waves. At the present time there are a number of the theories based on
completely integrable systems of equations, which are both generations of the
original known models and new ones. The modified Korteweg-de Vries equation,
the non- linear Schrodinger equation, the derivative non-linear Schrodinger
equation, Sine-Gordon equation, the reduced Maxwell-Bloch equation, Hirota
equation, the principal chiral field equations, and the equations of massive
Thirring model are gradually putting together a list of soliton equations,
which are usually to be found in non-linear optics theory.Comment: Latex, 17 pages, no figures, submitted to Pramana
Coherence creation in an optically thick medium by matched propagation of a chirped laser pulse pair
We consider the simultaneous propagation of a pair of Raman-resonant,
frequency-modulated (chirped) laser pulses in an optically thick medium,
modeled by an ensemble of -atoms. A self-organization ('matching`)
effect is shown for the chirped pulse pair, which leads to a quasi-lossless
propagation. Furthermore, we demonstrate that a well-defined coherent
superposition of the atomic ground states and, correspondingly, a coherence is
robustly created in the medium that can be controlled by amplitudes of the
laser pulses. The proposed scheme can be applied to substantially increase the
efficiency of the optical wave mixing processes, as well as in other nonlinear
processes where the initial preparation of a spatially extended medium in a
coherent superposition state is required
Coherent interaction of laser pulses in a resonant optically dense extended medium under the regime of strong field-matter coupling
Nonstationary pump-probe interaction between short laser pulses propagating
in a resonant optically dense coherent medium is considered. A special
attention is paid to the case, where the density of two-level particles is high
enough that a considerable part of the energy of relatively weak external
laser-fields can be coherently absorbed and reemitted by the medium. Thus, the
field of medium reaction plays a key role in the interaction processes, which
leads to the collective behavior of an atomic ensemble in the strongly coupled
light-matter system. Such behavior results in the fast excitation interchanges
between the field and a medium in the form of the optical ringing, which is
analogous to polariton beating in the solid-state optics. This collective
oscillating response, which can be treated as successive beats between light
wave-packets of different group velocities, is shown to significantly affect
propagation and amplification of the probe field under its nonlinear
interaction with a nearly copropagating pump pulse. Depending on the probe-pump
time delay, the probe transmission spectra show the appearance of either
specific doublet or coherent dip. The widths of these features are determined
by the density-dependent field-matter coupling coefficient and increase during
the propagation. Besides that, the widths of the coherent features, which
appear close to the resonance in the broadband probe-spectrum, exceed the
absorption-line width, since, under the strong-coupling regime, the frequency
of the optical ringing exceeds the rate of incoherent relaxation. Contrary to
the stationary strong-field effects, the density- and coordinate-dependent
transmission spectra of the probe manifest the importance of the collective
oscillations and cannot be obtained in the framework of the single-atom model.Comment: 10 pages, 8 figures, to be published in Phys. Rev.
Coherent responses of resonance atom layer to short optical pulse excitation
Coherent responses of resonance atom layer to short optical pulse excitation
are numerically considered. The inhomogeneous broadening of one-photon
transition, the local field effect, and the substrate dispersion are involved
into analysis. For a certain intensity of incident pulses a strong coherent
interaction in the form of sharp spikes of superradiation is observed in
transmitted radiation. The Lorentz field correction and the substrate
dispersion weaken the effect, providing additional spectral shifts. Specific
features of photon echo in the form of multiple responses to a double or triple
pulse excitation is discussed.Comment: only PDF,15 page
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