TE Plane Wave Research Articles

Revisiting optical absorption power density of inhomogeneous plane waves

We review the analytical expressions for the complex Poynting’s vector in the case of arbitrary plane-waves in a lossy isotropic medium. We demonstrate how these expressions can be used to recover the optical absorption power density Q, considering the divergence of the time-averaged Poynting vector. This quantity, proportional to the imaginary part of the dielectric function and the field intensity, i.e. Q∝|E|2ɛ”, is usually established for harmonic fields, using the Poynting’s identity. The derivation from the complex Poynting vector expression is more direct for TE-polarized homogeneous waves, but the derivation encompasses the other cases like inhomogeneous TM plane waves. As an application, the optical absorption profile Q(x) within 1D multilayers is detailed using matrix transfer method for both TE and TM plane waves, including the evanescent case.

DUAL-BAND BANDSTOP FILTERS BASED ON ULTRA THIN FREQUENCY SELECTIVE SURFACES

In this paper, we present designs for terahertz filters with two independent stopbands based on periodic metallic resonant structures patterned on the dielectric substrate. Two simple and thin structures are proposed to realize required characteristics for single-polarized and dual polarized filter designs. To realize single polarized one, a unit cell of the proposed periodic structure consists of two sets rectangular shape conducting metal patches patterned on the top of the dielectric substrate, and the dual-band response is due the lattice resonances observed in the unit cell. To realize dual polarized filter design, a modified unit cell is considered with additional patches on the bottom of the dielectric substrate. The patches on the bottom layer are the same ones as on the top layer but orthogonally oriented. For this case, polarization-independent frequency response can be obtained after geometric optimization of the unit cell because the top and the bottom layers resonantly interact with only the TE or TM incident plane wave to minimize cross coupling effects between the layers. In order to intensively understand the transmission performance of the proposed filters, a large number of simulations using integral equation method are performed based on the different values for permittivity, period of the unit cell, dielectric thickness, and geometric dimensions. The electric field distributions are analyzed to understand the mechanism of the resonance behavior.

Control of Time-Reversal Aperture by High-Precision Phase-Modulated and Dual-Polarized Metasurface

In this paper, we propose a novel design concept for the generation of special beams based on time-reversal aperture (TRA) theory. Firstly, different forms of TRAs are investigated to overcome the shortcomings of traditional TRA in special beam generation. Next, a wideband (26.11 % for TE and 19.5% for TM, respectively) dual-polarization phase modulation metasurface (MS) is designed. Subsequently, the designed MS illuminated by TE plane wave will generate sloping Bessel Beam, meanwhile, the accelerating beam will be generated by TM plane wave incident. Compared to the classical methods, the proposed MS not only achieves a dual-polarization independent phase shift range of more than 400° without dimensional changes, but also maintains a high transmittance with transmission loss lower than 0.3 dB. Finally, to verify the concept, the MS is manufactured and tested. The measured results show good agreement with the theoretic demonstrations and full-wave simulations.

Multipolar origin of electromagnetic transverse force resulting from two-wave interference

We propose a theoretical study on the electromagnetic forces resulting from the superposition of a TE and TM plane waves interacting with a sphere. Specifically, we first show that, under such an illumination condition, the sphere is subjected to a force transverse to the propagation direction of the waves. We then analyze the physical origin of this counter-intuitive behavior using a multipolar decomposition of the electromagnetic modes involved in that scattering process. This analysis reveals that interference effects, due to the two-wave illumination, lead to a Kerker-like asymmetric scattering behavior resulting in this peculiar transverse force.

Resonant Polariton Effects in a Structure of Equidistant Layers of a Single-Phase Hyperbolic Medium with Spatial Dispersion

It has been shown in the dissipationless limit that, if a TE or TM bulk plane wave is incident from outside on a finite planar structure consisting of nonmagnetic and antiferromagnetic dielectric layers, the inclusion of the spatial dispersion of the magnet in the case of a hyperbolic antiferromagnetic medium can lead to additional resonant refractive anomalies, in particular, effects of total reflection (transmission) of a plane electromagnetic wave and the formation of discrete localized magnon-polariton states against the continuous spectrum, and, in the regime of a one-dimensional resonant magnetic photonic crystal, to the superradiance effect.

A Spheroidal Model of Light Scattering by Nonspherical Particles

We have constructed a spheroidal model to solve the problem of light scattering by nonspherical particles. The semiaxes of the model spheroid are determined based on the requirement that the volumes of initial and model particles are equal, as well as the ratios of their longitudinal and transverse dimensions. This ensures the closeness of the optical properties of initial and model particles. This approach has been applied to prolate and oblate parallelepipeds, cylinders, and cones with the ratios between their larger and smaller dimensions equal to 2 or 10. The direction of propagation of the incident TE or TM plane wave was either parallel or perpendicular to the symmetry axis of particles and model spheroid. The particle size has been determined by dimensionless parameter $${{x}_{{v}}}$$ = $$2\pi {{r}_{{v}}}$$ /λ, which depends on the particle volume, since $${{r}_{{v}}}$$ is the radius of the equivolume sphere. In calculations, this parameter has been varied from small values to fairly large ones, $${{x}_{{v}}}$$ = 10. The applicability range of the model has been determined by comparing the results of numerical calculations performed by the rigorous separation of variables method for spheroids and the method of discrete dipoles for other nonspherical particles. It has been shown that the applicability range of the model for parallelepipeds, cylinders, and cones is wide enough for different parameters of the problem, in particular, if the parameter $${{x}_{{v}}}$$ ≤ 6, then the relative error of the model does not exceed 10–15%. To a large extent, this is related to the fact that the first maximum of the dependence of scattering factor Qsca on $${{x}_{{v}}}$$ is similar for particles of different shapes approximated by one and the same model spheroid.

Tunable light trapping and absorption enhancement with graphene-based complementary metasurfaces

Surface plasmon resonance (SPR) has been intensively investigated and widely exploited to trap the incident light and enhance absorption in the optoelectronic devices. The availability of graphene as a plasmonic material with strong half-metallicity and continuously tunable surface conductivity makes it promising to dynamically modulate the absorption enhancement with graphene-based metamaterials. Here we numerically demonstrate tunable light trapping and absorption enhancement can be realized with graphene-based complementary metamaterials. Furthermore, we also explore the polarization sensitivity in the proposed device, in which case either TM or TE plane wave at the specific wavelength can be efficiently absorbed by simply manipulating the Fermi energy of graphene. Therefore, this work can find potential applications in the next generation of photodetectors with tunable spectral and polarization selectivity in the mid-infrared and terahertz (THz) regimes.

О сфероидальной модели рассеяния света несферическими частицами

AbstractWe have constructed a spheroidal model to solve the problem of light scattering by nonspherical particles. The semiaxes of the model spheroid are determined based on the requirement that the volumes of initial and model particles are equal, as well as the ratios of their longitudinal and transverse dimensions. This ensures the closeness of the optical properties of initial and model particles. This approach has been applied to prolate and oblate parallelepipeds, cylinders, and cones with the ratios between their larger and smaller dimensions equal to 2 or 10. The direction of propagation of the incident TE or TM plane wave was either parallel or perpendicular to the symmetry axis of particles and model spheroid. The particle size has been determined by dimensionless parameter $${{x}_{{v}}}$$ = $$2\pi {{r}_{{v}}}$$ /λ, which depends on the particle volume, since $${{r}_{{v}}}$$ is the radius of the equivolume sphere. In calculations, this parameter has been varied from small values to fairly large ones, $${{x}_{{v}}}$$ = 10. The applicability range of the model has been determined by comparing the results of numerical calculations performed by the rigorous separation of variables method for spheroids and the method of discrete dipoles for other nonspherical particles. It has been shown that the applicability range of the model for parallelepipeds, cylinders, and cones is wide enough for different parameters of the problem, in particular, if the parameter $${{x}_{{v}}}$$ ≤ 6, then the relative error of the model does not exceed 10–15%. To a large extent, this is related to the fact that the first maximum of the dependence of scattering factor Q _sca on $${{x}_{{v}}}$$ is similar for particles of different shapes approximated by one and the same model spheroid.

Optical manipulation of small particles on the surface of a material

Optical trapping and manipulation of dielectric particles on the surface of a dielectric prism using TE plane waves are demonstrated in the Rayleigh scattering regime. The interference of four counter propagating evanescent waves forms a standing wave on the planar surface and the trapping is realized based on the gradient force. Two mirrors are used to manipulate the trapped particles in any arbitrary direction on the surface. The required trapping potential and the irradiance within the Rayleigh scattering regime are computed. A hypothesis is developed to pull the particles at a maximum force toward the surface for further demonstration of this configuration. The standing wave on the surface of the prism using TE Gaussian beams are demonstrated for practical illustration of this study.

Theoretical investigation of a tunable external cavity diode laser based on a single cavity all-dielectric thin-film Fabry–Perot filter

The single cavity all-dielectric thin film Fabry–Perot filter (s-AFPF) has been theoretically investigated in this paper as a means of tuning the wavelength in an external cavity diode laser (ECDL), and the means of limiting longitudinal mode hopping has been also theoretically investigated. When a TE or TM plane wave irradiates an s-AFPF, a quasi-linear relationship is found in a certain wavelength range between the optical intensity peak transmittance wavelength of s-AFPF and the cosine value of plane wave incident angle at s-AFPF. Based on this feature, we proposed and theoretically investigated an ECDL configuration based on an s-AFPF. By theoretical calculation, the actuator flat edge against the steel ball may be replaced by a bent edge to convert the mode-hop wavelength region into mode-hop-free wavelength region. The ECDL can be used in the application of environmental monitoring, atomic and molecular laser spectroscopy research, precise measurements, and so on.

TE Plane Wave Scattering from Periodic Rough Surfaces with Perfect Conductivity: Image Integral Equation of the First Type

TE Plane Wave Scattering from Periodic Rough Surfaces with Perfect Conductivity: Image Integral Equation of the First Type

Optical properties of transiently-excited semiconductor hyperbolic metamaterials

Ultrafast optical excitation of photocarriers has the potential to transform undoped semiconductor superlattices into semiconductor hyperbolic metamaterials (SHMs). In this paper, we investigate the optical properties associated with such ultrafast topological transitions. We first show reflectance, transmittance, and absorption under TE and TM plane wave incidence. In the unpumped state, the superlattice exhibits a frequency region with high reflectance (>80%) and a region with low reflectance (<1%) for both TE and TM polarizations over a wide range of incidence angles. In contrast, in the photopumped state, the reflectance for both frequencies and polarizations is very low (<1%) for a similar range of angles. Interestingly, this system can function as an all-optical reflection switch on ultrafast timescales. Furthermore, for TM incidence and close to the epsilon-near-zero point of the longitudinal permittivity, directional perfect absorption on ultrafast timescales may also be achieved. Finally, we discuss the onset of negative refraction in the photopumped state.

Effects of Curved Wavefronts on Conductor-Backed Reflection-Only Free-Space Material Characterization Techniques.

A true plane wave is often not physically realizable in a laboratory environment. Therefore, wavefront curvature introduces a form of systematic error into Free-space material characterization methods. Free-space material characterization is important to the determination of the electric permittivity and magnetic permeability of conductor-backed and in situ materials. This paper performs an error analysis of the impact on wavefront curvature on a Free-space method called the two-thickness method. This paper compares the extracted electric and magnetic permeability computed with a plane wave versus a line source for a low-loss dielectric and magnetic radar absorbing material. These steps are conducted for TE and TM plane waves and electric and magnetic line sources.

Shift and elimination of microwave Fabry-Perot resonances in a dielectric covered with a thin metal layer

In this paper, we consider a plane electromagnetic wave incident onto a dielectric plate, which has one surface covered with a thin layer of metal. An oblique incident angle was considered for the TE (s polarization in optic) and TM (p polarization) plane waves. The thin metal layer is treated as an infinitesimal thickness. It was characterized by a surface conductivity and accounted for by a tangential magnetic field component step induced by the current flow in the metal layer. Compact expressions, which describe the reflection, transmission and absorption in a dielectric plate covered with a thin layer of metal, have been obtained. It was shown that by choosing the appropriate surface conductivity, the Fabry-Perot transmission resonances can be shifted to the position where the maximum reflection is observed in the case of an uncovered dielectric. On the other hand, the elimination of the Fabry-Perot resonances can be also achieved by choosing a proper metal surface conductivity. Measurements of the reflection from the glass covered with a thin layer of metal have been performed in a wide microwave frequency range (2–12 GHz) revealing a large difference in the measured reflection coefficient from the dielectric and metalized surfaces. The measured results fit well with those calculated by employing analytical expressions obtained in this paper.

Guided-mode triggered switching between TE orders of a metal-based grating-waveguide

An undulated metal-based dielectric slab waveguide is shown to exhibit a high contrast broadband switching effect in the angular spectrum between the 0th order Fresnel reflection and the propagating -1st reflected diffraction orders. The switching trigger is the synchronous collinear coupling of an incident TE plane wave to the close-to-cutoff forward- and backward-propagating fundamental TE0 mode of the waveguide via the +1st and -2nd order of the periodic undulation.

FDTD model of non-magnetized plasma coatings on metals based on collocated surface impedance boundary conditions

A finite-difference time-domain (FDTD) model is developed for non-magnetized plasma thin layers on metal surfaces illuminated by vertical polarization (TE) and parallel polarization (TM) plane waves at oblique incidence. The model is based on collocated first-order surface impedance boundary conditions (SIBCs), permitting one to remove the plasma coating and the substrate from the computational space. The reflection of TE and TM plane waves at varying oblique incident angles from the plasma coating surfaces is simulated. The results are numerically verified by the comparison with the exact results in the one-dimensional situation. Magnitude and phase error of the calculated reflection coefficients are studied to illustrate that the proposed model has greatly improved accuracy over the original SIBCs implementation. Finally, we calculate the radar cross-section (RCS) of a perfectly conducting cube covered with plasma coatings utilizing the proposed collocated SIBCs, which further demonstrates the practical application of the model.

Negative phase velocity and negative refraction in orthorhombic dielectric–magnetic lossy media with polarization along one of principal axes

The characteristics of the TE plane wave propagations in orthorhombic dielectric–magnetic lossy media are investigated. The special case for the electric field being parallel to one principal axis and the wave vector lying wholly in the plane formed by the other two principal axes is considered. The dissipation is taken into account by letting the elements of the permittivity and the permeability tensors to be complex. The general condition on the negative phase velocity for uniform TE plane waves is provided in terms of material parameters and the propagation angle. The numerical calculations for the angles between the average Poynting vector and the phase velocity are performed in order to justify the theoretical analysis. In addition, the TE refraction between the free space and the orthorhombic dielectric–magnetic lossy media are also considered and the general condition on the negative refraction is derived.

Multilayer Periodic and Random Metamaterial Structures: Analysis and Applications

In recent years, multilayer photonic bandgap structures comprising stacks of alternating layers of positive and negative index have been proposed for a variety of applications, such as perfect imaging, filters, sensors, coatings for tailored emittance, absorptance, etc. Following a brief review of the history of negative index materials, the performance of such stacks is reviewed, with emphasis on analysis of plane wave and beam propagation, and possible applications in sensing. First, the use of the transfer matrix method to analyze plane wave propagation in such structures to determine the transmittance and reflectance is developed. Examples of cases where the Bragg bandgap and the so-called zero \(n \) > gap can be used for possible applications in sensing are illustrated. Next, the transfer matrix approach is extended to simulate the spatial evolution of a collection of propagating and nonpropagating TE and TM plane waves (or plane wave spectra) incident on such multilayer structures. The use of the complex Poynting theorem in checking the computations, as well as monitoring powers and the stored electric or magnetic energy in any section of the multilayer stack, is illustrated, along with its use in designing alternating positive and negative index structures with optimal gain to compensate for losses in the negative index material. Finally, the robustness of PIM-NIM stacks with respect to randomness in the dimensions of the PIM-NIM structure is examined. This should be useful in determining the performance of such structures when they are physically fabricated.

Wideband Analysis of Periodic Structures at Oblique Incidence by Material Independent FDTD Algorithm

A novel implementation of the finite difference time domain (FDTD) algorithm to analyze periodic structures over a wideband with oblique incident waves is presented. Based on the field transformation treatment, the method splits each component of the transformed fields of the electric displacement vector and the magnetic induction intensity vector into three parts in a simple manner. This treatment is independent of material and easily implemented, so that it could be utilized in a wide range of periodic structure analysis. The advantage of the method is demonstrated through two numerical examples. One is Jerusalem cross frequency selective surfaces (JCFSS) with anisotropic lossy media in the millimeter wave band, and excited by the TM wave at θ = 20° and the TE wave at θ = 45°, respectively. Another is a photonic periodic structure with rectangular holes for the visible and infrared bands, where it acts as a dispersive medium, with the incident TE plane wave at θ = 30°. The results are in good agreement with those of CST Microwave Studio, and thereby the validity of the method is verified.

TE Scattering From Concaved Wedges With Longitudinal Corrugations

An exact series solution for the oblique scattering from a corrugated wedge with concaved edge is formulated for TE plane wave using the radial mode matching technique. The scattered and guided fields are represented in terms of an infinite series of radial modes with unknown coefficients. By applying the appropriate boundary conditions, the coefficients of the scattered field are obtained. The diffraction coefficient of a corrugated wedge is subsequently derived from the scattered field.