Excitonic surface polaritons in ZnTe

Excitonic surface polaritons are excited resonantly in ZnTe utilizing attenuated total reflection (ATR). Lineshape analyses of ATR and normal-incidence-reflection spectra yield the eigenenergies of excitonic surface and bulk polaritons. Comparison of ATR and reflection spectra with luminescence spectra invalidates a recently published attribution of luminescence maxima to excitonic surface polaritons.     

Effect of quantizing magnetic field on the spectrum and damping of polaritons in double two-dimensional electronic systems

Nonradiative (surface and bulk) polaritons in a semiconductor structure composed of two heterojunctions GaAs/Al_xGa_1?x As are investigated under the integer quantum Hall effect (IQHE) conditions. The dispersive, polarization, and energy characteristics of these polaritons are determined including energy dissipation in the two-dimensional electron semiconductor layers. The phase and group velocities of surface and bulk polaritons are shown to be quantized under the IQHE conditions. It is found that resonance coupling of two surface polariton modes may occur in double GaAs/Al_xGa_1?x As heterojunctions. Possible experimental observation of nonradiative polaritons is discussed.     

Surface magnetic polaritons on uniaxial antiferromagnets

The dispersion relation of surface polaritons for a uniaxial antiferromagnet are calculated taking account of retardation. In the presence of an external magnetic field, one finds that inequivalent propagation occurs in the Voigt configuration (±n? × H₀). For a high frequency permeability smaller than a critical value, the surface polaritons in the ?n? × H₀ direction, where n? is the normal to the interface, merges in the same frequency domain as the bulk polaritons.     

Effect of dissipation on the properties of surface polaritons in GaAs/AlGaAs heterojunctions in a quantizing magnetic field

A study is reported of nonradiative surface and bulk polaritons in GaAs/Al_xGa_1−x As real heterojunctions under conditions favoring integer-quantum Hall effect (IQHE) and in the presence of dissipation in a two-dimensional electron layer. The conditions of their existence, the spectrum, and damping have been determined. It is shown that under IQHE conditions all aspects of surface and bulk polaritons are quantized. It is found that, as the wave number is varied, surface and bulk polaritons can transform continuously into one another. The possibilities of experimental observation of nonradiative polaritons are discussed. Fiz. Tverd. Tela (St. Petersburg) 41, 705–711 (April 1999)     

Dispersion relation for surface-localized magnetic polaritons and magnetostatic waves in antiferromagnetic superlattice

In addition to the general dispersion equation for surface-localized magnetic polaritons and magnetostatic waves, which propagate in the system antiferromagnetic superlattice-antiferromagnet, we derive a simplified result for the long-wavelength limit λ?L (L is the period of superlattice) when the superlattice is found to behave like an anisotropic bulk medium (effective-medium approach). The dispersion curves and frequency region of the existence of the surface magnetic polaritons and magnetostatic waves are presented numerically for several values of the external magnetic field and for different antiferromagnetic materials.     

含单负材料三明治结构的电磁隧穿特性

在理论分析的基础上,结合实验研究了单负材料/正折射率材料(或单负材料)/单负材料三明治结构的电磁隧穿性质.这种结构的电磁隧穿来源于入射平面波与结构的表面或体极化激元的耦合,从理论上讨论并计算了正入射情况下这种结构中的极化激元的色散关系.发现:由单负材料作为边界而正折射率材料为中间层的三明治结构具有体极化激元,这种极化激元的共振频率随着中间层厚度的增加向低频移动;由不同性质的单负材料构成的三明治结构具有两条色散曲线,这两条色散曲线随着中间层厚度的增加而简并.随后基于L-C传输线技 关键词： 单负材料 极化激元 隧穿 L-C传输线')" href="#">L-C传输线     

Surface polaritons on semi-infinite anisotropic media

We have investigated the nature of polaritons which propagate on the surface of semi-infinite anisotropic dielectric and magnetic media and find that the surface polaritons are regular surface waves [i.e., the penetration constant α (ω) is real] only for special orientations of the wave vector k and of the normal to the surface n relative to the principal axes. In the case of biaxial crystals, regular surface polaritons occur when k and/or n is along a principal axis of the dielectric tensor ε(ω) for dielectric media [or the magnetic permeability tensor μ(ω) for magnetic media]. When k and n are both directed along principal axes, the surface polaritons are TM with E in the saggital plane for dielectric media. One finds that surface polaritons which are coupled photon-virtual surface dipole excitation modes can exist on “surface active” anisotropic media in addition to the familiar coupled photon-real surface dipole excitation modes. When neither k nor n are along principal axes, the surface polaritons that occur are, with the exception of special orientations, “generalized” surface waves [i.e., α(ω) is complex]. The Poynting vectors of the propagating surface polaritons are always in the plane of the surface but not, in general, along k. These results, which hold for uniaxial crystals, are also applicable to gyromagnetic media and to gyrodielectric media. This theory is also applicable to surface polaritons which propagate along the interface between two media, one or both of which is anisotropic, and with one or the other serving as the “surface active” medium.     

Magneto-phonon polaritons in two-dimension antiferromagnetic/ion-crystalic photonic crystals

Magneto-phonon polaritons in a two-dimension photonic crystal (PC) are discussed. This PC is constructed by embedding a periodical square lattice of ionic-crystal cylinders into an antiferromagnet. The two media are dispersive, with their individual resonant frequencies near each other. We first set up an effective-medium method to obtain the effective magnetic permeability and dielectric permittivity of the PC, followed by the dispersion relations of surface and bulk polaritons. There are a number of new surface polaritons, and two new distinctive bulk polariton bands in which the negative refraction and left-handedness can appear. The numerical calculations are based on the example, FeF₂/TlBr PC.     

Effect of anisotropy on the photonic band gap and surface polaritons of a one-dimensional single-negative photonic crystal

The effect of anisotropy on the photonic band structure and surface polaritons of a one-dimensional photonic crystal made of uniaxially anisotropic epsilon-negative (ε<0,μ>0) and mu-negative (ε>0,μ<0) metamaterials is theoretically investigated. Two different cases of uniaxially anisotropic epsilon-negative and mu-negative metamaterials are considered. It is found out that for one case of anisotropy, one-dimensional photonic crystal does not have any single-negative band gap. As a result, it can not support the surface polaritons. While, for another case, the structure shows single-negative band gaps. So, the surface polaritons can be excited at the interface of such a photonic crystal. However, these surface polaritons, unlike the isotropic case, are not omnidirectional and they are restricted to a limited rang of the propagation constant.     

Virtual excitation type surface polaritons on anisotropic media

We discuss the nature of a new type of surface polariton which occurs on anisotropic media, involving a photon coupled to a surface virtual excitation. Dispersion curves are calculated for α-quartz, where both real excitation type and virtual excitation type surface polaritons are predicted. The dispersion curves for virtual excitation surface polaritons are found to remain at small wavevector, and the endpoints of the dispersion curves terminate on the bulk polariton dispersion curves in the two media. The virtual excitation surface polaritons which occur on gyromagnetic and gyrodielectric media are also noted.     

Effective-medium approach for surface-localized magnetic polaritons in magnetic (ferromagnetic and antiferromagnetic) superlattices

The general effective-medium dispersion relations are derived for surface-localized magnetic polaritons which propagate parallel to the surface between a superlattice and semi-infinite bulk material, as applied to ferromagnetic and antiferromagnetic superlattices, in the situation when a static magnetic field is applied in the plane of the layers and parallel to the magnetization. The dependence of the energy of the surface waves on the volume fraction of the ferromagnetic superlattice component and the influence of the external magnetic field on the spectrum of the surface magnetic polaritons for the antiferromagnetic superlattice are investigated. The spectrum of the surface-localized magnetic polaritons which appear at the junction of the magnetic (ferromagnetic and antiferromagnetic) superlattice with the magnetic material are more complex, in contrast to the cases of semi-infinite magnetic material or semi-infinite magnetic SL. It is essential that in all cases in the presence of the external magnetic field the spectrum of the magnetic polaritons are non-reciprocal. The properties of surface polaritons are discussed in detail for the system ferromagnetic superlattice (YIG/non magnet)/YAG and the antiferromagnetic superlattice (MnF₂/ZnF₂)/FeF₂.     

Nonlinear resonance-enhanced excitation of surface plasmon polaritons

We theoretically investigate nonlinear resonance-enhanced excitation of surface plasmon polaritons in a metal coated by a one-dimensional photonic crystal. Tunneling modes above the air-light line can be directly excited in this structure. Then, with suitable parameters, photon energy and momentum conservation between the tunneling mode and the surface plasmon polaritons can be realized by means of nonlinear four-wave mixing. Compared with the nonlinear excitation of surface plasmon polaritons in a bulk metal [Phys. Rev. Lett. 103, 266802 (2009)], the conversion efficiency in our structure is noticeably enhanced.     

Electromagnetic waves in uniaxial crystals with metallized boundaries: Mode conversion,pure reflections,and bulk polaritons

A theory is constructed for the reflection of plane electromagnetic waves in uniaxial crystals with a positive definite permittivity tensor and an arbitrarily oriented metallized boundary. The problem is solved both for general-position orientations corresponding to three-partial reflection and for special conditions allowing two-partial reflections: mode conversions when the incident and reflected waves belong to different sheets of the refraction surface and “pure” reflections when both waves belong to the same sheet. The space of pure reflections is shown to be formed by two types of optical-axis orientations: arbitrary directions in the plane of the crystal surface and in the plane of incidence. The configurations of the conversion surface for optically positive and negative crystals are investigated. A subspace of pure reflections that transform into one-partial bulk polaritons with the energy flux parallel to the surface at grazing incidence has been found. The domain of existence of such bulk eigenmodes is bounded by two “lines” of solutions. These are any directions along the boundary containing the optical axis for ordinary polaritons and the direction along the projection of the optical axis onto the surface at an arbitrary orientation of the axis with respect to the boundary for extraordinary polaritons.     

Polariton modes in semiconductor superlattices

Polariton electric fields and dispersion relations of some important complex-basis superlattices have been derived by means of electromagnetic theory and the Bloch's theorem. The spatial distribution of the polariton electric fields shows an interesting physical picture: the polaritons are mainly bulk modes as the wavenumber k is small and become typical interface modes with very strong peak intensities as k increases.     

An additional kind of nonlinear s-polarized surface plasmon polaritons

We have explored the dispersion relations for s-polarized surface plasmon polaritons guided by a metal film sandwiched between a linear substrate and a cladding with an intensity-dependent refractive index. In contrast to a previous paper we found surface plasmon polaritons for this configuration which exhibit a definite power threshold and a limited range for permitted propagation constants as well.     

Far infrared measurements of bulk and surface phonons in GaAs/AlAs superlattices

We have used far-infrared oblique-incidence reflection spectroscopy to study bulk phonon polaritons, and attenuated total reflection (ATR) spectroscopy to study surface phonon polaritons, in long-period GaAs/Al_xGa_1–xAs and short-period GaAs/AlAs superlattices. Results on the former are in good agreement with an effective-medium bulk-slab model of the dielectric tensor of the superlattice; results on the latter are analysed in terms of a model that contains dielectric-tensor contributions from the confined optic phonons.     

Bulk spin-wave electrodynamics of an antiferromagnetic plate in a constant external electric field

Using the example of a plate of an easy-axis centrosymmetric antiferromagnet, the conditions are determined under which an external constant electric field qualitatively changes not only the character of refraction of a bulk TM wave incident from vacuum onto the antiferromagnet surface but also the structure of the spectrum of propagating bulk magnons. The relation of the discovered effects to the shape of the refraction surface of TM polaritons is studied.     

A high-resolution Fourier transform spectrometer for far infrared magneto-optic spectroscopy of magnetic materials

We describe a high-resolution (0.015 cm⁻¹) Fourier transform spectrometer which has been developed to investigate bulk and surface magnetic polaritons in magnetic media by far infrared magneto-optic spectroscopy. The spectrometer uses a novel combination of laser-controlled sampling of the interferogram and phase modulation of the infrared beam to combine very accurate sampling and low signal-to-noise ratio. The spectrometer is coupled to a liquid helium cryostat with a 7 T superconducting magnet, and a liquid helium-cooled silicon bolometer is used as the detector. Samples can be mounted in the cryostat for polarised oblique incidence reflection measurements in the Voigt geometry with the applied magnetic field vertical. Measurements on surface polaritons are made by using attenuated total reflection (ATR) spectroscopy with silicon prisms to obtain the necessary wave vector enhancement. The resolution of the instrument is demonstrated with measurements on the rotational lines of water vapour, and a selection of measurements on a bulk single crystal of FeF₂, a uniaxial antiferromagnet, is presented to illustrate the performance of the instrument as a probe of magnetic excitations.     

Surface polaritons in a dielectric at a boundary with a metal in crossed electric and magnetic fields

AbstractThe spectrum of surface polaritons in a dielectric at a boundary with an ideal metal or a super-conductor in crossed constant electric and magnetic fields is studied. It is shown that the polariton spectrum possesses strong nonreciprocity (polaritons with fixed frequency propagate only in one direction; this is the rectification effect) and depends strongly on the directions of the external fields and their ratios H ₀/E ₀.