20 research outputs found
Nonlinear optical effects in artificial materials
We consider some nonlinear phenomena in metamaterials with negative
refractive index properties. Our consideration includes a survey of previously
known results as well as identification of the phenomena that are important for
applications of this new field. We focus on optical behavior of thin films as
well as multi-wave interactions.Comment: 22 pages, no figures. Submitted in book "Nonlinear waves in complex
systems: energy flow and geometry
Coherent Amplification of Optical Pulses in Metamaterials
In this paper we theoretically study propagation of steady state ultrashort
pulse in dissipative medium. We considered two cases (i) medium consists of
lossy metallic nanostructures embedded into a gain material and (ii) the gain
material is embedded directly into the nanostructures. We found the shape and
velocity of an optical pulse coupled with the polarization wave.Comment: 9 pages, 5 figures, submitted to IEEE Tran
Random polarization dynamics in a resonant optical medium
Random optical-pulse polarization switching along an active optical medium in
the -configuration with spatially disordered occupation numbers of its
lower energy sub-level pair is described using the idealized integrable
Maxwell-Bloch model. Analytical results describing the light
polarization-switching statistics for the single self-induced transparency
pulse are compared with statistics obtained from direct Monte-Carlo numerical
simulations.Comment: 7 pages, 3 figure
Optical Pulse Dynamics in Active Metamaterials with Positive and Negative Refractive Index
We study numerically the propagation of two-color light pulses through a
metamaterial doped with active atoms such that the carrier frequencies of the
pulses are in resonance with two atomic transitions in the
configuration and that one color propagates in the regime of positive
refraction and the other in the regime of negative refraction. In such a
metamaterial, one resonant color of light propagates with positive and the
other with negative group velocity. We investigate nonlinear interaction of
these forward- and backward-propagating waves, and find self-trapped waves,
counter-propagating radiation waves, and hot spots of medium excitation.Comment: 9 pages, 6 figure
Optical Bistability in Nonlinear Optical Coupler with Negative Index Channel
We discuss a novel kind of nonlinear coupler with one channel filled with a
negative index material (NIM). The opposite directionality of the phase
velocity and the energy flow in the NIM channel facilitates an effective
feedback mechanism that leads to optical bistability and gap soliton formation
Stochastic Pulse Switching in a Degenerate Resonant Optical Medium
Using the idealized integrable Maxwell-Bloch model, we describe random
optical-pulse polarization switching along an active optical medium in the
Lambda-configuration with disordered occupation numbers of its lower energy
sub-level pair. The description combines complete integrability and stochastic
dynamics. For the single-soliton pulse, we derive the statistics of the
electric-field polarization ellipse at a given point along the medium in closed
form. If the average initial population difference of the two lower sub-levels
vanishes, we show that the pulse polarization will switch intermittently
between the two circular polarizations as it travels along the medium. If this
difference does not vanish, the pulse will eventually forever remain in the
circular polarization determined by which sub-level is more occupied on
average. We also derive the exact expressions for the statistics of the
polarization-switching dynamics, such as the probability distribution of the
distance between two consecutive switches and the percentage of the distance
along the medium the pulse spends in the elliptical polarization of a given
orientation in the case of vanishing average initial population difference. We
find that the latter distribution is given in terms of the well-known arcsine
law
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Modeling femtosecond pulse propagation in optical fibers.
Femtosecond pulse propagation in optical fibers requires consideration of higher-order nonlinear effects when implementing the non-linear Schroedinger equation. We show excellent agreement of our model with experimental results both for the temporal and phase features of the pulses. Ultrafast pulse propagation in optical fibers presents a number of challenges given the effect of nonlinearities which become important on such a short time scale. The modeling of femtosecond pulse propagation becomes, consequently, a harder task which has to account for all these effects. In this work, we have included higher order corrections in the non-linear Schroedinger equation and compared the numerical simulation results with experimental data. Our work, besides taking into account the temporal evolution of the pulse, keeps into account also the phase behavior of the electric field, which we compare with experimental results obtained with Frequency Resolved Optical Gating [l]. We also account for self-frequency shift of the pulse and obtain excellent agreement with the experimental results on the Raman shift