P-polarized Electromagnetic Waves Research Articles

Variable magnetic field electron spectrometer to measure hot electrons in the range of 50-460 keV.

Resonance absorption (RA) occurs when a p-polarized electromagnetic wave, obliquely incident on an inhomogeneous plasma, tunnels past its turning point and resonantly excites an electron plasma wave (EPW) at the critical density. This phenomenon is important, for instance, in the direct drive approach to inertial fusion energy and is a particular example of a wider phenomenon in plasma physics known as mode conversion, which is crucial for heating magnetic fusion devices, such as tokamaks, via RF heating. Direct measurement of these RA-generated EPW accelerated hot electrons, with energy in the range of a few tens to a few hundreds of keV, is a challenging task due to the relatively low deflecting magnetic fields needed. The solution described here is a magnetic electron spectrometer (MES) with a continually changing magnetic field, lower at the entrance of the MES and gradually increasing toward the end, that enables the measurement of a wide spectral range of electrons with energies between 50 and 460keV. Electron spectra taken in a LaserNetUS RA experiment were acquired from plasmas generated by irradiating polymer targets with the combination of an ∼300ps pulse followed by a series of ten high intensity 50-200fs duration laser pulses from the ALEPH laser at Colorado State University. The high intensity beam is designed as spike trains of uneven duration and delay pulses in order to modify the RA phenomenon.

NON-REFLECTIVE INCIDENCE OF P-POLARIZED ELECTROMAGNETIC WAVES ON THE SOLID-STATE STRUCTURE "UNIAXIAL PLASMONIC METASURFACE — DIELECTRIC LAYER — METAL"

Subject and Purpose. The solid-state structures involving metasurfaces can be used to effectively control some of the basic properties of electromagnetic waves, like amplitude, phase and polarization. The present work is aimed at analyzing the new effects that may appear during incidence of p-polarized electromagnetic waves upon a solid-state structure involving a uniaxial plasmonic metasurface, a dielec- tric interlayer, and a layer of metal. Methods and Methodology. The conditions suitable for identifying the effects that result from the reflection of a p-polarized electro- magnetic wave incident upon a solid-state structure of the above described type have been sought for via numerical simulation. That has allowed finding the magnitudes of the essential parameters, such as angles of incidence and frequencies of the electromagnetic waves, as well as thicknesses of the dielectric interlayer, that could stipulate appearance of novel electromagnetic effects. Results. It has been shown that the solid-state structure involving a uniaxial plasmonic metasurface, a dielectric interlayer, and a layer of metal is capable, under certain conditions, to fully absorb an incident electromagnetic wave of p-polarization. Moreover, a new effect has been predicted, specifically that of full conversion of the incident p-polarized electromagnetic wave into a reflected wave of s-polariza- tion. The necessary condition is that the plane of incidence of the electromagnetic wave were at an acute angle to the principal symmetry axis of the plasmonic metasurface. Conclusions. The solid-state structures of the type involving a uniaxial plasmonic metasurface, a dielectric interlayer, and a layer of metal are characterized by unique reflective properties. They are capable of fully absorbing, under certain conditions, the p-polarized electromagnetic waves incident upon them. Such structures can be used for creating optical and nanoelectronic devices of new types.

Impact of non-linearity and non-integer dimension on the reflection and transmission coefficients

Presented manuscript is devoted to the study of reflection and transmission coefficients of a second-order nonlinear dielectric and linear dielectric NID interface excited by a P-polarized electromagnetic wave. Impact of the non-linearity of the NL medium and non-integer dimension of the NID medium are studied separately. The method of separation of variables is used to model the propagation of waves in NID medium and the solution of the non-linear wave equation is obtained by following the procedure of slowly varying amplitude approximation. We extend our analysis for special cases of the original geometry, i.e. epsilon negative non-linear, mu negative non-linear and epsilon negative NID mediums are considered in this regard. We also calculated the specific values of the permittivities, permeability and dimension of the NID medium for which maximum amplitude of the reflection and transmission coefficients can be achieved.

INFLUENCE OF UNIAXIAL PLASMON METASURFACE ON ANTIREFLECTION PROPERTIES OF DIELECTRIC LAYER

Subject and Purpose. Th e study of the eff ect of refl ectionless electromagnetic waves propagation through solid-state structures containing metasurfaces at its boundaries has a great scientifi c and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. Th e aim of this work is to study the eff ect of an anisotropic uniaxial plasmon metasurface located at the boundary of the dielectric layer on the eff ect of refl ectionless propagation of electromagnetic waves. The study of the effect of refl ectionless propagation of electromagnetic waves through solid-state structures containing metasurfaces at its boundaries is of great scientific and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. Methods and Methodology. Numerical simulations were used to study the effect of the refl ectionless electromagnetic waves propagation through an anisotropic uniaxial plasma metasurface lying on the dielectric layer. It is used to determine the thicknesses and permeability values of the dielectric layer, for which the effect was observed. Results. It is shown that the presence of an anisotropic uniaxial plasmon metasurface on the dielectric layer leads to a signifi cant conditions change of the eff ect of refl ectionless propagation of p-polarized electromagnetic waves along and across the main axis of anisotropy of the metasurface. It was shown that the metasurface removes the rigid restriction of the dielectric layer permeability value. To achieve the effect of refl ectionless propagation of electromagnetic waves, the permeability of the dielectric layer can be chosen within a wide range. Conclusion. Dielectric layers with anisotropic uniaxial plasmonic metasurfaces have signifi cantly better characteristics for the effect of refl ectionless propagation of electromagnetic waves. They can be used to create fundamentally new nanoelectronic and optical devices.

CHANGES IN ELECTROMAGNETIC WAVE POLARIZATION RESULTING FROM ITS REFLECTION AT A UNIAXIAL PLASMONIC METASURFACE ON TOP OF A DIELECTRIC LAYER

Subject and Purpose. The analysis of the electromagnetic waves’ polarizational transformations that may accompany their reflection from a metasurface is of considerable scientific and practical interest from the point of possibilities for improving characteristics of nanoelectronic and optical devices, and creating novel types of these. This work has been aimed at finding the conditions for efficient conversion of a p-polarized electromagnetic wave incident upon a uniaxial plasmonic metasurface at the boundary of a dielectric layer, into a wave of s-polarization. Methods and Methodology. The effects of conversion of p-polarized electromagnetic waves incident upon a uniaxial plasmonic metasurface, into s-polarized waves were explored through numerical modeling. The approach has allowed determining the wave frequencies and thicknesses of the dielectric layer best suitable for ensuring full conversion. Results. The presence of a uniaxial plasmonic metasurface on top of a dielectric layer can provide for full conversion of an incident p-polarized electromagnetic wave into a wave of s-polarization. As has been established, the effect takes place if the plane of incidence of the p-polarized wave makes an acute angle with the principal axis of the plasmonic metasurface. Another finding is that the full conversion is possible for a variety of permittivity values of the dielectric layer. Conclusions. The uniaxial plasmonic metasurface placed on a dielectric layer is characterized by unique reflective properties. It can have a noticeable impact on polarization of the p-polarized wave’s incident upon the layer. Dielectric layers provided with uniaxial metasurfaces can be used for creating optical and nanoelectronic devices of new types.

Induced resonant electromagnetic piercing in metalized photonic crystal structures

A metalized photonic crystal resonator in certain conditions can concentrate field close to the resonator-metal interface that causes an extraordinary resonant penetration of electromagnetic waves into metal. Here, we analyzed how a p-polarized electromagnetic wave interacting with a thin metal film through the 1D photonic crystal resonator generates the needle shaped Fano type absorption peaks in the terahertz region of frequencies. At inclined incidence, the absorption peaks exhibit properties of surface plasmon resonances with frequencies matching the standing modes of bare photonic crystal resonator at whispering incident angles.

A solver based on pseudo-spectral analytical time-domain method for the two-fluid plasma model

A number of physical processes in laser-plasma interaction can be described with the two-fluid plasma model. We report on a solver for the three-dimensional two-fluid plasma model equations. This solver is particularly suited for simulating the interaction between short laser pulses with plasmas. The fluid solver relies on two-step Lax–Wendroff split with a fourth-order Runge–Kutta scheme, and we use the Pseudo-Spectral Analytical Time-Domain (PSATD) method to solve Maxwell’s curl equations. Overall, this method is only based on finite difference schemes and fast Fourier transforms and does not require any grid staggering. The Pseudo-Spectral Analytical Time-Domain method removes the numerical dispersion for transverse electromagnetic wave propagation in the absence of current that is conventionally observed for other Maxwell solvers. The full algorithm is validated by conservation of energy and momentum when an electromagnetic pulse is launched onto a plasma ramp and by quantitative agreement with wave conversion of p-polarized electromagnetic wave onto a plasma ramp.

Parametric excitation surface waves at plasma boundary under action of p-polarized laser radiation

The parametric excitation of surface waves at the plasma boundary under the action of a p-polarized electromagnetic pump wave is analyzed. The instability, at which the pump wave decays into two surface electromagnetic TM modes, is considered. The dependence of the instability growth rate on the plasma electron density, the angle of incidence of the pump wave, and the direction of propagation of the excited surface waves is investigated. It is shown that the instability growth rate has a maximum value in the case when short-wave quasistatic surface waves are excited.

Effect of an Electric Field in the Heat Transfer between Metals in the Extreme Near Field

Radiative heat transfer between metals in the extreme near field in the presence of a potential difference between them has been calculated. Because of the coupling between the electric field of radiation and displacements of the surfaces, the radiative heat flux between two gold plates at nanometer distances that is due to p-polarized electromagnetic waves increases by many orders of magnitude at the variation of the potential difference from 0 to 10 V. The radiative mechanism of heat transfer is compared to the phonon mechanism associated with the electrostatic and van der Waals interactions. The phonon mechanism determined by the van der Waals interaction dominates at subnanometer distances and small potential difference. However, the radiative contribution dominates at nanometer distances because the phonon contribution decreases with increasing distance more rapidly than the radiative contribution. The results obtained in this work can be used to control heat fluxes at a nanoscale by means of the potential difference.

On the Theory of Quasi-Static Magnetic Field Generation Caused by Electromagnetic Wave Incidence on Semi-Infinite Plasma

Quasi-static magnetic field generation caused by the oblique incidence of a p-polarized electromagnetic wave on a semi-infinite plasma, in which the electron density exceeds the critical value, is considered. It is shown that the appearance of magnetic fields is caused by excitation of a nonlinear surface current at the zero harmonic of the pump wave.

Reflected and transmitted powers of p-polarized electromagnetic waves through a dielectric slab surrounded by double negative materials

In this paper, reflected, transmitted, and loss powers of p-polarized electromagnetic waves through a lossless dielectric slab embedded between two double negative media are studied. Lorentz and Drude medium models are both considered for the dispersion of the double negative materials in the surroundings. The dependences of reflected, transmitted, and loss powers on the incidence angle, incident wave frequency, and dielectric slab thickness are investigated. The results reveal many interesting features. The damping frequency has a slight effect on reflected, transmitted, and loss powers in most waveguide configurations considered. Moreover, the loss power is small and can be significantly reduced by considering Drude dispersion model and careful choosing of the proposed structure parameters.

Theory of Goos-Hänchen shift in graphene: Energy-flux method

We present a theoretical study of Goos-Hänchen shift and associated time delay of a p-polarized electromagnetic wave packet for total internal reflection at a plane interface between two media of different permittivity, with graphene at their interface. The study is based on the energy-flux method which takes into account the energy flux in graphene in addition to the energy flux in the incident, totally reflected, coupled incident-totally reflected and evanescent wave packets.

The excitation and detection of a leaky surface electromagnetic wave on a high-index dielectric grating in a prism-coupler geometry

A periodically corrugated interface between vacuum and a high-index dielectric medium supports a p-polarized leaky surface electromagnetic wave whose sagittal plane is perpendicular to the generators of the interface. This wave is bound to the surface in the vacuum region, but radiates into the high-index dielectric medium. We study the excitation of this wave by p-polarized light incident from a prism on whose planar base the highindex dielectric medium in the form of a film is bonded. The unilluminated surface of the film is periodically corrugated, and is in contact with vacuum. Peaks and dips in the dependence of several low-order diffraction efficiencies on the angle of incidence (Wood anomalies) are the signatures of the excitation of the surface wave.

Broadband wide-angle absorption enhancement due to mode conversion in cold unmagnetized plasmas with periodic density variations

We study theoretically the mode conversion and the associated resonant absorption of p-polarized electromagnetic waves into longitudinal plasma oscillations in cold, unmagnetized and stratified plasmas with periodic spatial density variations. We consider sinusoidal density configurations for which the frequency band where mode conversion occurs is well included within a transmission band of the one-dimensional plasma photonic crystal. We calculate the mode conversion coefficient, which measures the fraction of the electromagnetic wave energy absorbed into the plasma, and the spatial distribution of the magnetic field intensity for various values of the wave frequency and the incident angle using the invariant imbedding theory of mode conversion. We find that the absorption is greatly enhanced over a wide range of frequency and incident angle due to the interplay between the mode conversion and the photonic band structure. The enhancement occurs because for frequencies within a transmission band, the wave reflection is strongly suppressed and the waves penetrate more deeply into the inhomogeneous region, thereby increasing the possibility for them to reach many resonance points where the dielectric permittivity vanishes.

Spectrum and Optical Contrastivity of an Oxidized Comb-Like Silicon Photonic Crystal

A typical oxidized ternary photonic crystal – A/B/A/C N-periodic structure – is investigated analytically and numerically in the framework of the transfer matrix formalism. The influence of the oxidation on photonic gaps and the positions of perfect reflection areas for (SiO2/Si/SiO2/Air)N structure is calculated with regard for a transformation of the widths of silicon oxide layers. It is shown that the intrinsic optical contrastivity has a non-monotone behavior during the process of oxidation of silicon in the case of p-polarized electromagnetic waves. The found results will allow one to determine the optimal regimes of oxidation to obtain the needed optical properties of a photonic material.

Nonexistence of pureS- andP-polarized surface waves at the interface between a perfect dielectric and a real metal

It is known that, at optical frequencies, a simple interface between a perfect dielectric and a real metal can sustain the propagation of surface plasmon polaritons only for P-polarized electromagnetic waves, being S-polarized surface plasmons are prohibited. In this work, we formally show that, strictly speaking, both polarization states are in fact prohibited and that only P-polarized pseudosurface waves are allowed, which is what is encountered in the applications. The existence of such pseudosurface modes allows one to reconcile theory and experimental evidence, but also sets limits for them to be considered as modes bound to the interface.

High-sensitivity sensing based on intensity-interrogated Bloch surface wave sensors

A high-sensitivity sensing scheme based on Bloch surface wave is presented with the simple intensity interrogation configuration. The p-polarized electromagnetic surface wave is designed to be excited in a one-dimensional photonic crystal band-gap structure, and support a rather steep resonance dip, much sharper than that of the well-known surface plasmon resonance (SPR). Although the angular shift of this Bloch-surface-wave-based sensor is not as sensitive, the intensity measurement proves to be a more suitable scheme for Bloch surface wave based sensors, thanks to the sharpness of their resonance. Through detection of glycerol in water solution for different concentrations, the intensity sensitivity of our Bloch-surface-wave-based sensor significantly surpasses that of the conventional SPR-based sensors. Experimental results show that the sensor could achieve a detection limit as low as 7.5×10−7 refractive index units in a simple lab setup, which is much simpler than many of the much more complicated SPR-based platforms.

Total transparency of a two-moving-magnetized-plasma-layer structure

Abstract In the present Letter the transparency of a two-moving-magnetized-plasma-layer structure irradiated by an electromagnetic wave is investigated theoretically and its resonant conditions are determined. Here, the direction of the external magnetic field is normal to the plasma surface and two layers move with different velocities parallel to the interface. The effects of the external magnetic field, speed of plasma layers and the magnitude of the wave number component on transparency are simulated. These investigations for S-polarized and P-polarized electromagnetic waves have been done separately.

Perfect absorption at Zenneck wave to plane wave transition

We theoretically demonstrate that there is an angle of incidence and frequency at which a p-polarized electromagnetic wave can be perfectly absorbed without reflection by a half-space of lossy indefinite anisotropic medium. We show that this perfect absorption occurs when the Zenneck wave guided by a surface of indefinite medium transits to a homogenous plane wave. This angular and frequency selectivity of the absorption can find a use for photovoltaic systems.

Transverse spin of a surface polariton

We consider a p-polarized surface electromagnetic wave (a classical surface polariton) at the interface between the vacuum and a metal or left-handed medium. We show that the evanescent electromagnetic waves forming the surface polariton inevitably possess a backward spin energy flow, which, together with a superluminal orbital energy flow, form the total Poynting vector. This spin energy flow generates a well-defined (but not quantized) spin angular momentum of surface polaritons which is orthogonal to the propagation direction. The spin of evanescent waves arises from the imaginary longitudinal component of the electric field which makes the polarization effectively elliptical in the propagation plane. We also examine the connection between the spin and chirality of evanescent modes.