Amplification Of Electromagnetic Waves Research Articles

Dynamic switching from coherent perfect absorption to parametric amplification in a nonlinear spoof plasmonic waveguide

Coherent perfect absorption (CPA) and amplification of electromagnetic waves are converse phenomena, where incoming radiations are coherently dissipated or amplified by structured incidences. Realizing such two phenomena simultaneously in a single device may benefit various applications such as biological sensing, photo detection, radar stealth, solar-thermal energy sharing, and wireless communications. However, previous experimental realizations of CPA and amplification generally require precise controls to the loss and gain of a system, making dynamic switching between the absorption and amplification states a challenge. To this end, we propose a nonlinear approach to realize CPA and parametric amplification (PA) simultaneously at the same frequency and demonstrate experimentally dynamic switch from the CPA to PA states in a judiciously designed nonlinear spoof plasmonic waveguide. The measured output signal gain can be continuously tuned from −33 dB to 22 dB in a propagation length of 9.2 wavelengths. Compared to the traditional linear CPA, our approach relaxes the stringent requirements on device dimensions and material losses, opening a new route to actively modulate the electromagnetic waves with giant amplification-to-absorption contrast in a compact platform. The proposed nonlinear plasmonic platform has potential applications in on-chip systems and wireless communications.

Influence of Electron Collisions on Electromagnetic Modes of Plasma Produced by Multi-Photon Ionization of an Inert Gas

Collective electromagnetic modes in weakly ionized plasma formed by multiphoton ionization of inert gas atoms, in which the Ramsauer–Townsend effect takes place, are studied. It is shown that at a relatively low energy of photoelectrons of the order of 1 eV, typical for multiphoton ionization, amplification of electromagnetic waves is possible. Amplification is possible both in the case of rare collisions of photoelectrons with neutral atoms and for collision frequencies higher than electron plasma frequency. At photoelectron energies somewhat higher than 1 eV, aperiodic instability can develop with growth rate whose value is comparable to electron plasma frequency. Detailed analytical and numerical analysis of the effect of collisions of photoelectrons with neutral atoms on the dispersion law of electromagnetic wave and the growth rates of instabilities is presented.

Parametric amplification of electromagnetic waves produced by a flux-flow-oscillator made of YBa2Cu3O7−δ Josephson junction arrays

We observe parametric amplification of electromagnetic (EM) waves produced by a flux-flow oscillator made of YBa2Cu3O7−δ Josephson junctions arrays coupled to the resonant modes of a millimeter wave Fabry–Pérot resonator at a pump frequency fP = 45 GHz. For temperatures in the range (30–45) K, the frequency fS of the EM signal to be amplified could be tuned continuously in the range (1–25) GHz by an applied B-field induced flux Φ with a one-flux-quantum Φ0 periodicity. Consequently, we measured a significant parametric gain that is almost frequency independent, with a maximum of (8–10.4) dB reached at 40 K. For temperatures in the range (14–30) K, the magnetic field tunability of fS is gradually suppressed to a minimum of (1–5) GHz range where a parametric gain between 5 and 6 dB was measured. With an appropriate adjustment of design/fabrication parameters, our results suggest that the development of tunable MW generators/detectors as well as parametric amplifiers made of high transition temperature superconductors and operating in a wide range of temperatures (10 mK–77 K) is a reasonable and appealing possibility.

Dual-Polarized Nonreciprocal Spatial Amplification Active Metasurface

This letter presents a dual-polarized nonreciprocal active metasurface (MTS) for spatial electromagnetic wave amplification. The MTS is designed based on receiving, amplifying, and reradiating scheme. Two square patch antennas printed on the opposite sides of two-layer substrates are used as receiving and reradiating antennas, respectively. A T-shaped microstrip line coupling structure is adopted to achieve impedance matching and dc-block function. Two bipolar transistors, which are place on a pair of orthogonal microstrip feed lines, are used as amplifiers to achieve dual polarization spatial amplification of the electromagnetic wave. A prototype MTS is fabricated and tested to verify the design. The measured effective spatial amplification coefficients higher than 0 dB has a band from 4.88 to 5.19 GHz with the peak value of 10.4 dB. Besides, the proposed MTS is insensitive to polarization. The spatial amplification coefficients variation for different polarization is below 0.6 dB. The proposed MTS could be used in the radio frequency transceiver systems to reduce the pressure of the amplifier on the circuit board.

Design of high-power wide-band G-band third harmonic amplifier

To meet the demand of high-power and wide-band signal sources for G-band vacuum electronic devices, the research on G-band third harmonic amplifier is carried out. The amplifier utilizes the third harmonic current in the nonlinear beam-wave interaction of E-band TWT, and realizes G-band electromagnetic wave amplification by cascading harmonic interaction section. The design scheme of high performance and practical G-band wide-band high-power source adopts folded waveguide slow wave structure with modified circular bends, and the G-band third harmonic amplifier is simulated and optimized by using the microwave tube simulator package (MTSS) software. The result shows that the device can obtain harmonic output power greater than 3.6 W in the range of 15 GHz, with conversion gain＞33.3 dB and electronic efficiency＞0.36%. Compared with other miniaturized terahertz radiation sources in this band, it has superior performance in terms of output power and bandwidth, and thus provides a design basis for the subsequent research of G-band third harmonic amplifier.

The electromagnetic wave amplification in thin superconducting film in non-linear mixed state

In this paper the interaction of electromagnetic waves with the moving fluxons in the thin superconducting film on the dielectric substrate is considered. It is shown that in the case of flux-flow described by the Larkin-Ovchinnikov model, the amplification of electromagnetic wave can be observed. In this case, amplification can be achieved when the fluxons velocity is less than the phase velocity of the electromagnetic wave. It is revealed that the thin superconducting film in mixed state demonstrated nonreciprocal properties for backward and forward waves. The results obtained in this work allow to create amplifiers based on cuprate superconductors.

Near-field analysis of GaP nanocones

A complex near-field analysis of the GaP nanocones grown on GaP substrates is here demonstrated. The Zn-doped GaP nanocones and nanocones coated with Ag nanoparticles were investigated in transmission and illumination mode using different light sources. This analysis showed near-field enhanced emission of GaP nanocones at the local level. Moreover, the near-field analysis demonstrated the emission enhancement if the Ag coating of GaP nanocone was used. These highly resolved analysis demonstrate enhancement of electrical field in nanocone surfaces and favors the GaP nanocone surfaces for using in surface-enhanced Raman scattering substrates and other applications using the nanoscale electromagnetic wave amplification.

Reinventing the Zel'Dovich wheel

After reviewing the pioneering work by Zel'Dovich in which radiation is amplified perpendicular to the axis of a rotating conductor, we consider an alternative scattering arrangement. We demonstrate superradiant amplification of electromagnetic waves with orbital angular momentum, directed axially towards a rotating conductor. Taking into account recent advances in optics and condensed matter systems, our approach presents new possibilities for rotational superradiance experiments. We discuss remaining challenges that must be faced before a laboratory observation of the Zel'Dovich effect can be considered feasible.

Epsilon near zero metasurface for ultrawideband antenna gain enhancement and radar cross section reduction

A non-resonant metamaterial unit cell is proposed to design a metasurface for ultrawideband (UWB) gain enhancement and radar cross section (RCS) reduction of an UWB antenna. Epsilon near zero (ENZ) property and negative refractive index of metamaterial is achieved to ensure low loss and amplification of electromagnetic waves (EM) passing through it. The proposed metamaterial is designed on a 6 mm × 6 mm FR4 substrate with dielectric constant 4.4, height 1.6 mm and loss tangent 0.01. The unit cell is simulated with periodic boundary condition to get the properties of periodically arranged unit cells in one plane called metasurface. A Metasurface is designed by planar arrangement of 5×5 unit cells of proposed metamaterial unit cell and is kept at height of 2 mm above an ultrawideband planar microstrip antenna. Antenna system with metasurface has physical and electrical dimensions of 32 × 32 × 5.2 mm3 and 0.34λ0×0.34λ0×0.05λ0 respectively, where λ0 is the free-space wavelength at 3.2 GHz. The bandwidth of UWB patch antenna (3.1–10.6 GHz) is unaffected by the presence of metasurface. The analysis of radiation mechanism shows the phase difference of EM waves passing through metasurface with and without reflection is 300°–400°. This indicates emergence of coherent waves from metasurface and contributes in gain enhancement. Maximum gain is 5.7 dB at 6.8 GHz with radiation efficiency of 88.5% and maximum gain enhancement is 10.1 dB at 9.8 GHz. The reflection phase analysis of normal incident wave predicts the frequency for maximum RCS reduction as 6.4 GHz. Maximum RCS reduction of antenna with application of metasurface is 21 dB at 6.7 GHz. Significant gain enhancement and reduction of RCS is achieved for ultrawideband. The proposed antenna system metasurface with enhanced gain and reduced RCS is a good candidate for application in stealth and military platforms.

Different Geometries of Superheterodyne Amplification of Electromagnetic Beams in Waveguides Nitride-Dielectric

The superheterodyne amplification of electromagnetic waves is investigated when the resonant three-wave interaction of two electromagnetic waves with the space charge wave occurs in the waveguides nitride n-GaN, n-InN films-dielectric. The amplification of SCW waves due to the negative differential conductivity is investigated in nitride n-GaN, n-InN films at the frequencies f ≤ 400 GHz in the lower part of the terahertz (THz) range. The electromagnetic waves are either in the upper part of THz range or in the optical range. The superheterodyne amplification is considered in two geometries, the collinear one in which the three interacting waves travel in the same direction and the anti-collinear geometry where the second electromagnetic wave propagates in the opposite direction. The preferences and drawbacks of each geometry are pointed out. The finite width of space charge waves leads to decrease of increments of amplification.

MULTIPLE THREE-WAWE RESONANCES IN TWO-STREAM FREE-ELECTRON LASER WITH A HELICAL ELECTRON BEAM

Background. A powerful terahertz radiation sources creation is one of the perspective tendencies in relativistic plasma electronics. Nowadays there are few devices able to create powerful radiation in millimeter-infrared waveband (even in the part of this band). Therefore, theoretical research of novel powerful terahertz radiation sources, that are also characterized by broad frequency spectrum, is an actual problem.Objective. The aim of the paper is a study of the influence of multiple three-wave resonant interactions in the klystron type two-stream superheterodyne free-electron laser (TSFEL) with helical electron beam on the forming effectiveness of the powerful waves with broad frequency spectrum.Methods. In order to theoretically analyze multiple resonances of wave harmonics, as initial, we use quasihydrodynamic equation, the continuity equation and Maxwell’s equations. We apply the hierarchic approach to the theory of oscillations and waves to the equations of motion and continuity, Maxwell’s equations are solved by means of the slowly varying amplitudemethod. As a result, we derive a system of differential equations for complex amplitudes of SCW electric field strength harmonics which we analyze by standard methods.Results. It was shown that in the two-stream superheterodyne FELs, utilizing the two-stream instability in helical electron beams as an additional electromagnetic wave amplification mechanism, the powerful multiharmonic space charge wavewith broad frequency spectrum forms due to multiple resonant interactions. The spectrum width of such wave is larger compared to the spectrum width in TSFELs utilizing straight electron beams. It is also found out that amplification rates in such TSFELs are higher.Conclusions. An application of helical electron beams in multiharmonic TSFELs using multiple resonant interactions leads to the improvement of their amplification characteristics, frequency spectrum widening in multiharmonic signal generation mode, and to overall geometric dimensions decreasing compared to TSFELs utilizing straight beams.Keywords: two-stream superheterodyne free-electron laser; two-stream instability; helical electron beams; three-wave resonances.

Numerical simulation of Raman and Brillouin laser-pulse amplification in a magnetized plasma

AbstractWe apply an Eulerian Vlasov code to study the amplification of an ultra-short seed pulse via stimulated Raman and Brillouin backscattering of energy from a long pump pulse, assumed at constant amplitude, in a plasma embedded in an external magnetic field. Detailed analysis of the spectra developed during the amplification process are presented, together with the evolution showing the pump depletion, accompanied by the counter-propagating seed-pulse amplification, compression and increased steepness of the waveform. In addition to the problem of the amplification of ultra-short seed pulses, there is an obvious academic interest in the study of problems of amplification of electromagnetic waves observed in many situations in laboratory plasmas and in the magnetosphere and other geophysical situations, such as in the environments of planets, where important variations in the presence and strength of magnetic fields are observed. The numerical code solves a one-dimensional relativistic Vlasov–Maxwell set of equations for a plasma in a magnetic field for both electrons and ions. We also apply the code to the problem of wakefield acceleration. The absence of noise in the Eulerian Vlasov code allows one to follow the evolution of the system with an accurate representation of the phase-space structures of the distribution functions.

Amplification of electromagnetic waves excited by a chain of propagating magnetic vortices in YBa2Cu3O7−δ Josephson-junction arrays at 77 K and above

When a soliton propagates in a discrete lattice it excites small-amplitude linear waves in its wake. In a dc current-biased Josephson-junction (JJ) array these manifest as electromagnetic (EM) waves excited by a (magnetic field induced) chain of propagating magnetic vortices. When the vortex velocity and the phase velocity of one of the excited EM waves match, phase-locking occurs. This produces resonant steps in the current–voltage characteristics where amplification of EM radiation occurs. We report the first observation of phase-locking-induced amplification of EM radiation at 77 K and above in JJ arrays made of high temperature superconductors.

Superheterodyne amplification of electromagnetic waves of optical and terahertz bands in gallium nitride films

Superheterodyne amplification of electromagnetic waves of optical and terahertz bands in the case of three-wave interaction in n-GaN films with the space change wave of millimeter band amplified due to negative differential resistance is studied. It is shown that amplification of the space change wave in n-GaN films may be achieved on higher frequencies f ≤ 500 GHz than when using GaAs. The case of three-wave resonant interaction of two counter-propagating waves with the space charge wave is considered for the waveguide on based on GaN film on dielectric substrate. It is shown that gain of electromagnetic waves of optical band may reach 20–40 dB on the waveguide lengths of up to 100 μm.

Ultimate On-Chip Quantum Amplifier

We report amplification of electromagnetic waves by a single artificial atom in open 1D space. Our three-level artificial atom--a superconducting quantum circuit--coupled to a transmission line presents an analog of a natural atom in open space. The system is the most fundamental quantum amplifier whose gain is limited by a spontaneous emission mechanism. The noise performance is determined by the quantum noise revealed in the spectrum of spontaneous emission, also characterized in our experiments.

Focusing and amplification of electromagnetic waves by time reversal in an leaky reverberation chamber

Abstract In this article, time reversal is used to generate high power microwave pulses from a low power arbitrary wave generator. We use a reverberation chamber with an aperture on the front face and we take advantage of the pulse compression property of time reversal. High amplitude peaks are generated outside the chamber thanks to the long spreading time of the signals inside. We study the amplitude of this peak and the width of the focal spot with respect to the different experimental parameters. A gain of 18 dB compared to a directive antenna of the same aperture is obtained.

Электродинамика тектонических процессов и электромагнитное профилирование земной коры в Антарктическом регионе

This paper discusses the problems of the natural Earth pulse electromagnetic radiation occurrence and it's usage for the Earth interior exploration. The main attention is paid to radiation of the radiowave diapason (from ~1 kHz to ~1 MHz) which sources is located inside the Earth lithosphere. The nonlinear aspect of mechanic – electromagnetic interaction and electromagnetic wave propagation is discussed. The different models of such a radiation generation and propagation are considered. We have proposed the model of such radiation generation based on the initiation of optical vibrations of complex crystal lattice and therefore associated electromagnetic oscillations that appear due to formation and movement of point, linear (dislocation) and volume (microcracks, pores) defects of crystals. In solid state physics the electromagnetic radiation associated with inherent (optical) lattice vibrations is called polariton radiation. As long as intensity of defect creation is in direct proportion to deformation of the crystal, the intensity of the signal generated will be maximal in maximal deformation zones of the Earth crust. This fact allows the application of this radiation for the Earth crust structure study. Referring to polariton emission, the strained rock is active medium, i.e. the existence of radiation stimulates creation and vanishing of defects leading to radiation amplification. Such mechanism of non-linear amplification of electromagnetic waves together with “transparency windows” existence may explain the observed ultraweak attenuation of such electromagnetic waves in the Earth crust. In this work, we gave the examples of geopolariton radiation usage for investigations of the glaciers in Antarctic region.

Electrodynamics of tectonics processes and electromagnetic profiling of the Earth crust in Antarctic region

This paper discusses the problems of the natural Earth pulse electromagnetic radiation occurrence and it's usage for the Earth interior exploration. The main attention is paid to radiation of the radiowave diapason (from ~1 kHz to ~1 MHz) which sources is located inside the Earth lithosphere. The nonlinear aspect of mechanic – electromagnetic interaction and electromagnetic wave propagation is discussed. The different models of such a radiation generation and propagation are considered. We have proposed the model of such radiation generation based on the initiation of optical vibrations of complex crystal lattice and therefore associated electromagnetic oscillations that appear due to formation and movement of point, linear (dislocation) and volume (microcracks, pores) defects of crystals. In solid state physics the electromagnetic radiation associated with inherent (optical) lattice vibrations is called polariton radiation. As long as intensity of defect creation is in direct proportion to deformation of the crystal, the intensity of the signal generated will be maximal in maximal deformation zones of the Earth crust. This fact allows the application of this radiation for the Earth crust structure study. Referring to polariton emission, the strained rock is active medium, i.e. the existence of radiation stimulates creation and vanishing of defects leading to radiation amplification. Such mechanism of non-linear amplification of electromagnetic waves together with “transparency windows” existence may explain the observed ultraweak attenuation of such electromagnetic waves in the Earth crust. In this work, we gave the examples of geopolariton radiation usage for investigations of the glaciers in Antarctic region.

Amplification of electromagnetic waves in the process of tunneling electrons between nanotubes

Amplification of electromagnetic waves in the process of tunneling electrons between nanotubes

Current driven electromagnetic wave amplification by double quantum wire superlattice

We analyze the electrodynamic interaction of an incident terahertz electromagnetic wave with a current-carrying lateral double-quantum-wire superlattice (at normal incidence). The superlattice (in the x-y plane) is taken to consist of two parallel quantum-wire sublattices, each of period d, shifted with respect to each other by distance Δ in the transverse y direction. The parallel quantum wires of the sublattices are all oriented in the x direction. The two sublattices are taken to carry equal steady currents in opposite directions, and are coupled by Coulomb forces alone, with tunneling neglected. We recently showed that quasi-one-dimensional plasmons of such double-quantum-wire superlattice systems become unstable when the electron drift velocity falls between the phase velocities of the acoustic and optical plasmon modes of the Coulomb-coupled wire subsystems. Here, we employ a random phase approximation for plasmon dispersion taken jointly with the full system of Maxwell equations to describe the electrodynamic interaction of the incident terahertz electromagnetic radiation with the superlattice electron system. Coupling of the electromagnetic wave with the plasmon excitations is provided by introducing a metal grating with the grating stripes oriented perpendicular to the quantum wires. We have determined the transmission, absorption, and reflection coefficients for an incident terahertz electromagnetic wave propagating through the grating-superlattice system, demonstrating that amplification of the terahertz electromagnetic radiation occurs in the region of plasma instability. Our numerical calculations show that this effect occurs at experimentally achievable drift velocities in GaAs-based structures.