Electromagnetic Solitons Research Articles

An exact solution for electromagnetic solitons in relativistic plasmas

In this paper, the dynamics of electromagnetic solitons in relativistic plasmas is studied. An exact solution is obtained for the governing nonlinear Schrödinger equation along with perturbation terms. The solitary wave ansatz is used to carry out this integration. The domain restriction of the parameters is also identified.

One-dimensional EM solitons in ultrashort intense laser pulse-partially stripped plasmas

The one-dimensional electromagnetic (EM) envelope solitons in ultrashort intense laser pulse-partially stripped plasmas were discussed based on the wave equation of intense laser pulse propagating in partially stripped plasmas. Under the weakly relativistic assumption, a modified nonlinear Schrödinger (NLS) equation describing the evolution of the EM field was derived. The analytical analysis shows that in the ultra-short broad beam limits, the relativistic nonlinearity and striction nonlinearity cancel each other, and a one-dimensional laser pulse envelope soliton can be formed only due to the polarization nonlinearity. The relationship between the characteristics of soliton and the parameters of laser pulse and partially stripped plasmas was discussed by numerical analysis.

Numerical Simulation of Electromagnetic Solitons and Their Interaction with Matter

A suitable correction of the Maxwell model brings to an enlargement of the space of solutions, allowing for the existence of solitons in vacuum. We review the basic achievements of the theory and discuss some approximation results based on an explicit finite-difference technique. The experiments in two dimensions simulate travelling solitary electromagnetic waves, and show their interaction with conductive walls. In particular, the classical dispersion, exhibited by the passage of a photon through a small aperture, is examined.

Electromagnetic solitons in a system of graphene planes with Anderson impurities

We consider the Maxwell equations for the electromagnetic-field propagation in a system of graphene planes with Anderson impurities. A phenomenological equation is obtained in the form of an analog of the classical 1 + 1-dimensional sine-Gordon equation. Electrons are considered within the quantum formalism taking into account the dispersion-law variations in the presence of an impurity subsystem. The phenomenological equation is analyzed numerically. It was found that the formation of a forbidden band in the graphene spectrum influenced the propagation of ultrashort optical pulses.

Electromagnetic solitons in a system of quantum dots taking into account the Hubbard interaction

We consider the Maxwell equations for an electromagnetic field propagating in a solid with a three-dimensional superlattice of quantum dots linked by strong tunneling along one axis, where electrons with different spin projections are affected by the strong Coulomb repulsion at a single site. We obtain a phenomenological equation in the form of the classical 1+1-dimensional sine-Gordon equation. Electrons are considered within the framework of quantum formalism taking into account the changes in the dispersion law provided by the presence of Coulomb interactions. The phenomenological equation is solved numerically, and the influence of Coulomb repulsion and the degree of band population on the propagation of ultra-short optical pulses is analyzed.

The formation of relativistic electromagnetic solitons in plasma Bragg gratings induced by two counter-propagating laser pulses

The generation of relativistic electromagnetic solitons in plasma with spatiotemporal density modulation is investigated. When two counter-propagating laser pulses overlap in underdense plasma, the interaction between the pulses and plasma modulates the electron and ion densities resulting in localized, stable, long-living relativistic electromagnetic solitons. They are caused by the Stimulated Raman Scattering instability. The dependence of the formation of relativistic electromagnetic solitons on the ion motion, plasma parameters, and laser parameters is studied by particle-in-cell simulations as well.

Dynamics and damping of electromagnetic solitons in the carbon nanotube bundles

The possible existence of the electromagnetic solitons in carbon nanotubes is analyzed. Solitons appear as a result of a simultaneous change in the classical electron distribution function and the electric field produced by the nonequilibrium electrons in carbon nanotube. The effective equations are obtained for the dynamics of electromagnetic field with allowance for the interband transitions causing soliton damping. The numerical results are presented evidencing the existence of solitons in carbon nanotubes. The propagation dynamics is studied for the periodic electromagnetic waves in the bundles of carbon nanotubes. The shape of electromagnetic wave is found to change during its propagation.

Matched soliton pairs of four-wave mixing in molecular magnets

We investigate the nonlinear dynamics of four-wave mixing in molecular magnets, and show that the matched and coupled electromagnetic soliton pairs can be formed in molecular magnets via a four-wave mixing. It is shown that both bright and dark soliton pairs can propagate through a crystal of molecular magnets and their carrier frequencies are adjustable within the terahertz and sub-terahertz frequency regimes.

Interaction of ultrashort light pulses with carbon nanotubes

The possibility of existence of electromagnetic solitons in carbon nanotubes is investigated on the basis of the coupled equations for the classical distribution function of electrons in such nanotubes and the Maxwell equations for electromagnetic fields. Solitons arise due to the matched change in the classical distribution function and the electric field formed by nonequilibrium electrons of a carbon nanotube. The data of numerical calculations, indicative of the existence of solitons, are reported.

Plasma Bragg gratings generated by the interaction of two counter-propagating laser pulses with plasmas

Solutions of electron and ion density gratings at the linear stage are given. Deep plasma gratings produced by the ponderomotive force of the interference of the two intersecting laser pulses are investigated. Dependence of the plasma grating on the plasma density, duration and intensity of the laser pulses are studied with 1D particle-in-cell (PIC) simulation. It is found that the density of peaks of such gratings can be 8 times the initial plasma density and can last a few picoseconds. We have found stable, long-lifetime electromagnetic solitons by use of these gratings. It is shown that the intensity for the formation of relativistic EM solitons with two crossed-propagating pulses is reduced to a great extent.

A lattice of electromagnetic solitons in a superlattice formed by a system of quantum dots

Considering the Maxwell equations for the electromagnetic-field propagation in a solid with a three-dimensional superlattice of quantum dots linked by strong tunneling along one axis, we obtained a phenomenological equation in the form of the classical 2+1-dimensional sine-Gordon equation. Electrons were considered classically in the formalism of the Boltzmann kinetic equation for the distribution function. Solutions were obtained as a soliton lattice for the vector potential of the electric field. These lattices emerge as a consequence of the coherent change of the classical distribution function and the electric field generated by tunneling electrons in a system of quantum wells.

Solitons in relativistic laser-plasma interactions

Single or/and multipeak solitons in plasma under relativistic electromagnetic field are reviewed. The incident electromagnetic field is allowed to have a zero or/and nonzero initial constant amplitude. Some interesting numerical results are obtained that include a high-number multipeak laser pulse and single or/and low-number multipeak plasma wake structures. It is also shown that there exists a combination of soliton and oscillation waves for plasma wake field. Also, the electron density exhibits multi-caviton structure or the combination of caviton and oscillation. A complete eigenvalue spectrum of parameters is given wherein some higher peak numbers of multipeak electromagnetic solitons in the plasma are included. Moreover, some interesting scaling laws are presented for field energy via numerical approaches. Some implications of results are discussed.

Stimulated trapped electron acoustic wave scattering, electromagnetic soliton and ion vortices in intense laser interaction with subcritical plasmas

Stimulated trapped electron acoustic wave scattering by a linearly polarized intense laser in a subcritical plasma is studied by particle simulation. The scattering process is a three-wave parametric decay of the laser pump into a critical Stokes electromagnetic sideband wave and the trapped electron acoustic wave. As the ion acoustic wave grows in time, it breaks locally, followed by a large relativistic electromagnetic soliton. A new phenomenon, MeV ion vortex in ion phase space, forms by local electromagnetic and electrostatic fields inside the soliton. It is found that the electron acoustic wave mode is similar to the kinetic electrostatic electron nonlinear waves.

Stimulated trapped electron-acoustic wave scattering and ion-vortices in subcritical plasmas

Stimulated trapped electron-acoustic wave scattering instability by a linearly-polarized laser interacting with a plasma layer at a subcritical density range is studied by particle simulation. Its early behavior is almost the same whether ion dynamics is taken into account or not. However, when ion dynamics is considered, a large ion acoustic wave is excited, which grows with time and eventually breaks up locally, followed by the generation of a large amplitude electromagnetic soliton. As a new phenomenon, an ion-vortex structure in ion phase-space is formed due to the ion acceleration and trapping by high local electromagnetic and electrostatic fields inside the soliton. As the electromagnetic soliton is accelerated backwards, several ion-vortices are formed in the wake behind. Ion-vortices are also found in inhomogeneous subcritical plasmas. These ion-vortices are recognized as the Kelvin-Helmholtz instability patterns, likely to be formed due to a topological defect, i.e., the plasma density cavity in the electromagnetic soliton region, which exhibit the well-known paradigmatic Ying-Yang pattern.

Interaction of electromagnetic solitons in relativistic plasmas

Moving one-dimensional electromagnetic solitons formed in a weakly relativistic laser-plasma are studied in the generalized nonlinear Schroedinger equation model. Conserved quantities and moving soliton solutions are analytically derived in a closed form. Stability studies reveal a transition at maximum amplitude to an unstable cusp-soliton. Simulations of two interacting electromagnetic (EM) solitons show a critical dependence on the solitons' amplitude, velocity and mutual phase: resulting in either elastic collisions or a break up of the soliton pair.

Ion vortices in ion phase space in intense laser interaction with subcritical plasma

A novel stimulated trapped electron-acoustic wave scattering instability by a linearly polarized laser interacting with a subcritical density plasma layer is observed by particle simulation. Its spectrum in the early stage is well-explained by a resonant three-wave parametric decay process and it takes place whether the ion dynamics are taken into account or not. When ion dynamics are considered, the excitation of the ion electrostatic wave, the generation of the electromagnetic (EM) soliton and the formation of ion vortices due to the large EM soliton, etc., are studied.

Standing Ultrashort Relativistic Solitons in Overdense Plasmas

By using a one-dimensional self-consistent relativistic fluid model, an investigation is made numerically on relativistic electromagnetic solitons with a high intensity in cold overdense plasmas with an electrons' initial velocity opposite to the laser propagating direction. Two types of standing solitons with zero group velocity are found at the given electrons' initial velocities. One is single-humped with a weakly relativistic intensity; the another is multi-humped with a strong relativistic amplitude. The properties of these two types of solitons are presented in detail.

Spectrum of electromagnetic solitons in relativistic plasma

A complete eigenvalue spectrum of the parameters is given wherein some higher peak numbers of multipeak electromagnetic solitons in plasma are included. Moreover some interesting scaling laws are obtained for field energy via numerical approaches.

Ion dynamics effect in forming relativistic solitons in plasmas

By using one-dimensional self-consistent relativistic fluid model, moving relativistic electromagnetic solitons with high intensity in electron-ion plasmas where the ion dynamics is taken into account are investigated numerically. It is demonstrated that two types of relativistic solitons with a precisely defined group velocity can occur in underdense and overdense plasmas with a given different background density. One is single-humped with weak scalar and vector potential amplitude; the other is multi-humped with high one. For these two types of solitons, the eigenvalue spectra of the group velocity versus the background density are found. The existence of soliton solutions is investigated in plasmas with a different background density, and the properties of these solitons are presented in detail.

Electromagnetic solitons in a system of carbon nanotubes

The possibility of existence of electromagnetic solitons is explored based on the coupled equations for the classical function of electron distribution in carbon nanotubes and the Maxwell equations for the electromagnetic field. The solitons emerge due to a concerted change in the classical distribution function and the electric field generated by the nonequilibrium electrons of a carbon nanotube. An efficient equation was obtained to describe the electromagnetic-field dynamics. The data of numerical calculations indicating the existence of solitons are given.