We consider quasiperiodic nonconservative perturbations of two-dimensional nonlinear Hamiltonian systems. We introduce the notion of a degenerate resonance and study the topology of a degenerate ...resonance zone with odd and even orders of degeneracy. A special attention is paid the oscillation synchronization while an invariant torus is passing through the resonance zone. We establish the existence of synchronization intervals with respect to a control parameter. The study is based on the analysis of a pendulum–type averaged system determining the dynamics in the resonance zone.
We study quasiperiodic nonconservative perturbations of two-dimensional Hamiltonian systems with nonmonotone rotation. We study the behavior of solutions in neighborhoods of resonance energy levels ...close to degenerate ones. We find conditions for the existence of resonance quasiperiodic solutions (m-dimensional invariant tori in the extended phase space) and study bifurcations in resonance zones. The results are illustrated by an example of asymmetric Duffing equation for which we also solve the problem of constructing solutions of unperturbed equations.
We study plasmonic properties of highly doped InP in the mid-infrared (IR) range. InP was grown by metal-organic vapor phase epitaxy (MOVPE) with the growth conditions optimized to achieve high free ...electron concentrations by doping with silicon. The permittivity of the grown material was found by fitting the calculated infrared reflectance spectra to the measured ones. The retrieved permittivity was then used to simulate surface plasmon polaritons (SPPs) propagation on flat and structured surfaces, and the simulation results were verified in direct experiments. SPPs at the top and bottom interfaces of the grown epilayer were excited by the prism coupling. A high-index Ge hemispherical prism provides efficient coupling conditions of SPPs on flat surfaces and facilitates acquiring their dispersion diagrams. We observed diffraction into symmetry-prohibited diffraction orders stimulated by the excitation of surface plasmon-polaritons in a periodically structured epilayer. Characterization shows good agreement between the theory and experimental results and confirms that highly doped InP is an effective plasmonic material aiming it for applications in the mid-IR wavelength range.
We present a review of some fundamental results in the theory of dynamical systems, which have led to the discovery of dynamical chaos and its three forms, namely, two classical forms, such as ...conservative chaos and dissipative chaos, as well as the completely new third form, the so-called mixed dynamics in which the sets of attractors and repellers have non-empty intersection. The major part of the work is devoted to homoclinic Poincaré trajectories, i.e., doubly asymptotic trajectories to saddle periodic ones, as the main elements of dynamical chaos. Using simple examples, we show the appearance of such trajectories during periodic perturbations of two-dimensional conservative systems. As is known, the homoclinic trajectories were discovered by Poincaré. In this work, we discuss the problem (the planar circular restricted three-body problem) solving which this discovery was made. Some interesting facts concerning its history are given in the appendix.
Quasiperiodic nonconservative perturbations of two-dimensional Hamiltonian systems are studied. The behavior of solutions in a neighborhood of resonance and nonresonance levels is considered. ...Conditions for the existence of resonant quasiperiodic solutions (
m
-dimensional resonance tori) are found, and the global behavior of solutions in domains separated from the unperturbed separatrices is discussed. The results are illustrated by the example of the Duffing equation with the homoclinic figure eight of a saddle.
We report stimulated emission in the 2.8-3.5 μm wavelength range from HgTe/CdHgTe quantum well (QW) heterostructures at temperatures available with thermoelectric cooling. The structures were ...designed to suppress the Auger recombination by implementing narrow (1.5 - 2 nm wide) QWs. We conclude that Peltier cooled operation is feasible in lasers based on such structures, making them of interest for spectroscopy applications in the atmospheric transparency window from 3 to 5 μm.
Various designs of dielectric waveguides made of heterostructures with CdHgTe quantum wells grown by molecular beam epitaxy have been studied to generate stimulated emission in the 15–30 μm ...wavelength range. The reduction of radiation losses in optimized structures has made it possible to reduce the threshold intensity of the generation of stimulated emission to ~100 W/cm
2
. Modernized growth technology has ensured the reduction of the residual cadmium content in HgCdTe quantum wells to 2.5%, which has allowed us to increase the threshold energy of Auger recombination, as well as the maximum temperature for the observation of stimulated emission at interband transitions above 100 K. The results obtained are prerequisites for the implementation of coherent radiation sources exceeding in characteristics of lead–tin chalcogenide lasers used in the 15–30 μm spectral range.
Photoluminescence and laser emission spectra of CdHgTe solid-solution quantum-well structures with microdisk cavities of different diameters are demonstrated. The presence of a cavity is shown to ...contribute to an increase in the maximum operating temperature of generation as compared to the unprocessed structure.
Metamorphic laser heterostructures In(Sb, As)/In
0.81
Ga
0.19
As/In
0.75
Al
0.25
As with InSb/InAs/InGaAs composite quantum wells based on submonolayer InSb insertions in a 10-nm InAs layer have been ...grown by molecular beam epitaxy on GaAs (001) substrates. Stimulated emission at a wavelength of λ ~ 2.86 μm at temperatures of 10–60 K at optical pumping has been demonstrated in such structures without an optical cavity. The threshold pump power density is about 5 kW/cm
2
at a temperature of 10 K.
Abstract
Polycrystalline Tb
x
Dy
1-x
R
0.1
Fe
2-z
Co
z
(R = Nd, Pr, x = 0.2, 0.3; z = 0, 1.3) cubic Laves phase alloys with MgCu2-type structure were prepared by arc melting followed by homogenizing ...annealing. The crystal structure, magnetic properties, and magnetostriction have been investigated. Compounds with high values of magnetostrictive susceptibility were found in the temperature range 150-300 K. Compounds with partial substitution of cobalt for iron demonstrate a change in the sign of anisotropic magnetostriction. This work continues the search for magnetostrictive materials with inexpensive neodymium and praseodymium.
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