Plasmonic crystal waveguides

We study the properties of electromagnetic waves propagating along the waveguides with a periodic core created by alternating metal and dielectric layers, the so-called quasi-one-dimensional plasmonic crystal waveguides. Such waveguides can be symmetric or asymmetric, depending on the cladding or substrate material properties, as well as on the termination of the periodic structure. We analyze the dispersion characteristics as well as the profiles of the guided modes for several types of waveguide structure.     

Effect of the anisotropy of a conducting layer on the dispersion law of electromagnetic waves in layered metal-dielectric structures

The dispersion laws of electromagnetic waves in layered periodic metal-dielectric structures with anisotropic metal layers have been theoretically analyzed. It has been found that the anisotropy of metal layers is responsible for the appearance of additional allowed energy bands for photons. It has been shown that these bands correspond to plasma (Langmuir) waves propagating in anisotropic metal layers of the structure. Conditions under which the directions of group and phase velocities of Langmuir waves coincide or are opposite have been determined. It has been shown that the penetration of the electromagnetic field of Langmuir waves into dielectric layers is exponentially weak and this field is primarily concentrated in metal layers, where it oscillates in the direction perpendicular to the plane of the layers.     

Nonlinear waves guided by a dielectric slab

We consider dispersion relations and field structure of TE-polarized guided waves travelling along an asymmetric dielectric slab surrounded by two different nonlinear media. For a given configuration there are four types of guided waves. Three of this four types possess at least one field maximum outside the slab region and have no counterpart in linear waveguide optics. The solutions of the dispersion relations depend now on an additional parameter making them more flexible with respect to the linear limit.     

A dielectric rod waveguide coupled with metal rectangular waveguide

Measurements have been done in the millimeter wave region on a composite waveguide which comprises a dielectric rod waveguide connecting two metal rectangular waveguides. Such a waveguide has been used by us in a Josephson harmonic mixer installed in a small metal cryostat, to prevent the thermal invasion from outside environment and to transmit both signal and LO waves with small losses. The measured transmission loss, that is caused mainly by the coupling loss between metal rectangular waveguides (TE₁₀ mode) and a dielectric rod waveguide (HE₁₁ mode), has been less than 2dB in the frequency range of 52–104 GHz.     

Polarization properties of surface plasmon polaritons at the boundary of topological insulators with the axion effect

Properties of surface plasmon polariton waves are theoretically studied in structures containing topological insulators with the axion effect. The effect of axion properties on dispersion, localization, and polarization of plasmon polaritons is analyzed. A possibility of determining the axion effect from the variation in the plasmon-polariton polarization is shown, and conditions for enhancement of polarization effects are revealed in waveguide structures of the dielectric?metal?dielectric type.     

非线性平板光波导中TM波的网络分析

用横向等效网络方法分析了非线性平板波导中TM的色散关系和场分布.这种方法基于传输线理论,把非线性介质波导中复杂的电磁场问题等效于电路网络问题,用横向谐振技术得到色散方程.用数值方法计算了不同非线性机制下三层平板非线性波导中的TM波传输特性.     

Generation and amplification of terahertz electromagnetic waves in a plasma waveguide with a dielectric rod and an annular degenerate plasma

The theoretical investigation of terahertz waves and their excitation by electron beam injection in a cylindrical metallic plasma waveguide is investigated. This metallic waveguide includes a cold collisionless unmagnetized annular degenerate plasma and a dielectric rod. The dispersion characteristics of these waves, the frequency spectra of fast and slow E-modes waves (transverse magnetic field), are studied. Also, the effects of the dielectric permittivity, the radius of the dielectric rod and the radius of the plasma on the frequency spectra and the time growth rate of waves are simulated. In addition, the electric field profiles in this waveguide are plotted.     

Nonexponentially Decaying Electromagnetic Waves Localized at the Boundary of Anisotropic Metal–Dielectric Structures

The possibility of the existence of a special class of surface electromagnetic waves with amplitude decreasing nonexponentially as they pass into an anisotropic metal–dielectric structure that borders the isotropic dielectric has been shown. The dispersion equation describing the propagation of such special surface waves has been obtained, and their attenuation coefficients and formula for electric and magnetic fields in contacting media have also been found. The expressions for the longitudinal and transverse components of the Poynting vector and volume density of electric and magnetic energy of special surface waves have been obtained. Numerical calculations for the layered metal–dielectric nanostructure that is described by a uniaxial tensor of effective dielectric permeability have been carried out Decaying.     

Metamaterial layer in rectangular waveguide

The changes in the dispersion characteristics of modes of isotropic metamaterial layer in a rectangular waveguide have been analyzed. It is shown that metal walls significantly affect the mode dispersion due to the redistribution of energy fluxes and broaden the waveguiding properties of the layer to the propagation range of fast waves. A variation in the waveguide parameters makes it possible, in particular, to implement an interesting class of eigenmodes with fast forward and slow backward waves.     

Natural Electromagnetic Waves in a Circular Waveguide with a Chiral and a Dielectric Layer

Based on particular solutions of a system of wave equations which describe electromagnetic processes in an unbounded biisotropic medium and are represented in the form of generalized power series, a dispersion equation is obtained for a two-layer circular waveguide with a chiral and a dielectric layer. The solution of the dispersion equation is analyzed for some types of natural waves.     

Propagation of surface plasmon polaritons in anisotropic MIM and IMI structures

Electromagnetic wave propagation through waveguide structures consisting of anisotropic dielectric layers, assisted by surface plasmon-polaritons (SPPs) is theoretically studied. Dispersion relations corresponding to both short range and long range coupled SPP modes in metal/insulator/metal (MIM) and insulator/metal/insulator (IMI) structures, taking into consideration the anisotropy of the insulator, are derived and numerically solved. The dispersion has a prominent dependence on the anisotropy of the dielectric environment. The dependence of propagation on the misalignments of the optic axes of the insulator has also been investigated.     

Guided modes in anisotropic metal bound waveguides

The dispersion relation determining guided modes in electro-optic (EO) waveguides sandwiched by metallic ground- and cover-layer electrodes has been deduced. The metal generally has a complex dielectric constant ε = ε′ + iε′′, with ε′ < 0 and ε′′ > 0. It is shown that for the reflection at a waveguide/metal interface, when −ε′ ≫ ε′′, the phase shifts on the reflection for TE- and TM-guided waves have opposite signs. This in turn results in a significant modification to waveguide dispersion characteristics and leads to an unusual phenomenon in the guided waves: under some conditions, the metal bound waveguides support higher-order guided modes, but may not allow guiding of the fund-amental and/or lower-order modes. This revised version was published online in November 2006 with corrections to the Cover Date.     

Nonlinear s-polarized surface plasmon polaritons

We have examined the dispersion relations for s-polarized surface plasmon polaritons, guided by (a) the interface between a semi-infinite metal and dielectric medium, and (b) a metal film bounded by semi-infinite dielectric media for situations in which one or more of the dielectric media are characterized by an intensity-dependent refractive index. We found that s-polarized waves satisfy the dispersion relations for very thin metal films bounded by nonlinear dielectric media. These waves exist only for power levels above a threshold that depends on the material parameters. We also comment on the experimental feasibility of observing these waves.     

SPM of nonlinear surface plasmon waveguides

Pulse propagation equation of nonlinear dispersion surface plasmon waveguide is educed strictly from wave equation. The nonlinear coefficient is defined and then used to assess and compare the nonlinear characteristic of three popular 1-D surface plasmon waveguides: the single metal–dielectric interface, the metal slab bounded by dielectric and the dielectric slab bounded by metal. SPM (self-phase modulation) of the typical surface plasmon waveguide is predicted and discussed.     

Guided modes in slab waveguides with a left handed material cover or substrate

We study guided modes propagating along a dielectric slab waveguide with a left handed material (LHM) cover or substrate. The dispersion relation is derived by using normalized waveguide parameters. An analytical method is then proposed to calculate the universal dispersion curves. Different from a slab waveguide with a LHM core, we find that guidance properties are strongly dependent on dielectric permittivity ε and magnetic permeability μ of the substrate and cover layers. For oscillating guided modes, fundamental zero order mode is not always absence, sometimes it exists in a restricted range of normalized propagation constant. First order mode behaves as other higher order modes and exists up to infinite high frequency. Higher order modes have no double degeneracy in the case of LHM cover layer. For surface guided modes, the existence and the type of the mode solutions with respect to different parameters are classified systematically and discussed in detail. Unlike a slab waveguide with a LHM core where the dispersion curve of TE₁ surface mode continues with that of oscillating TE₁ mode, the dispersion curve of TE₁ surface mode continues with that of oscillating TE₀ mode. It seems that the two different kinds of modes compensate each other to form one whole mode. Both TE and TM guided modes are discussed.     

Low-dimensional waveguide microwave photonic crystals

Structures containing periodically alternating elements, which are a source of high-order waves, are investigated as low-dimensional waveguide microwave photonic crystals. The band character of the transmittance and the reflectance of a photonic crystal, which consists of sequentially alternating dielectric layers and thin metallic plates partially overlapping the waveguide section, is revealed by the numerical modeling and the experimental investigation of amplitude-frequency characteristics. It has been shown that the application of metallic plates with gaps in the structure of the photonic crystal made it possible to decrease its longitudinal size substantially compared with photonic crystals fabricated based on elements made of alternating dielectric layers with various permittivities.     

基于金属包覆磁性波导结构的磁光Bragg器件特性分析

使用金属包覆磁性波导中的磁光耦合理论分析了静磁表面波与导波光在金属／电介质／钇铁石榴石／钆镓石榴石结构中的磁光共线作用，讨论了金属覆层和斜向场对磁光模式转换效率的影响。计算表明，金属包覆波导可以提高磁光作用，通过调节金属覆层与磁性薄膜间距得到了比空气／4a铁石榴石／钆镓石榴石的传统三明治波导情形高8．7dB的模式转换效率；而同时优化偏置磁场方向和金属包覆波导参数，模式转换效率可以进一步提高5．25dB。因此，金属包覆波导可以用于提高磁光Bragg器件性能，在微波和光信息处理等方面具有广阔的应用前蒂。     

Nonlinear guided waves and symmetry breaking in left-handed waveguides

We analyze nonlinear guided waves in a planar waveguide made of a left-handed material surrounded by a Kerr-like nonlinear dielectric, and predict that such a waveguide can support fast and slow symmetric and antisymmetric nonlinear modes. We study the symmetry breaking bifurcation and asymmetric modes in such a symmetric structure. The analysis of nonlinear dispersion properties of the guided waves shows that the modes can be either forward or backward.     

Theoretical investigation of hierarchical sub-wavelength photonic structures fabricated using high-order waveguide-mode interference lithograph

This paper presents the theoretical investigation of hierarchical sub-wavelength photonic structures with various periods and numbers of layers, which were fabricated using a high-order waveguide-mode interference field. A 442-nm laser was used to excite high-order waveguide modes in an asymmetric metal-cladding dielectric waveguide structure. The dispersion curve of the waveguide modes was theoretically analyzed, and the distribution of the interference field of high-order waveguide modes was numerically simulated using the finite-element method. The various dependences of the characteristics of hierarchical sub-wavelength photonic structures on the thickness and refractive index of the photoresist and the waveguide mode were investigated in detail. These hierarchical sub-wavelength photonic structures have various periods and numbers of layers and can be fabricated by a simple and low-cost method.