Quantum Theory of Surface Polaritons in Semi-Infinite Dielectric Systems

The interaction system of a semi-infinite diatomic dielectric and the electromagnetic field propagating parallelly to the surface is studied. The long-wave optical phonon modes of the semi-infinite dielectric are calculated including the electronic polarizability by a quantum-mechanical theory. Retardation effects are neglected. A quantum field theory method of surface polaritons is developed to calculate the operator describing the interaction between a photon and the phonon polarization fields of the semi-infinite crystal, with explicit inclusion of surface effects. The dispersion relations of the surface phonon-polaritons are derived and discussed. The results are in good agreement with those obtained by the conventional, macroscopic dielectric theory of surface polaritons and experimental ATR (attenuated total reflection) spectra. The dispersion cuwes of polariton leaking modes caused by the interaction between bulk TO mode with surface effect and photons are presented in a graphical form. The k_||-dependence of the electric field strength in each polariton branch is calculated and presented also in a graphical form. We also research the spatial dependence of the field strength in each polariton branch. It is found that these properties are influenced and modulated by the surface phonons because of the interaction between photons and the surface phonon modes of the semi-infinite dielectric system. Hence the divergent nature (diffraction effect) of light propagating along the fib& and waveguides is restrained. We present a method how to use the boundary conditions in the quantum theory, which will be discussed in detail.     

Nonlinear surface polaritons in 2D electron system in high magnetic field

The paper deals with the theoretical investigation of nonlinear surface polaritons (NSP) in isolated two-dimensional electron system (2DES) arranged at the interface between linear and nonlinear media and placed into the external quantizing magnetic field directed perpendicularly to 2DES. We consider that nonlinear medium dielectric permeability depends upon the tangential component of electric field only. It is shown that under the integer quantum Hall effect conditions all NSP characteristics are represented by the quantized values. It is found that the NSP spectrum contains two NSP modes - high-frequency and low-frequency ones. It is shown that the NSP can exist only in the case where the value of tangential component of electric field at the interface is less than a certain critical value. It is found that the resonant interaction between the NSP high-frequency mode and surface polariton mode occurs in the vicinity of the cyclotron resonance subharmonic. Received 23 September 2001 / Received in final form 31 January 2002 Published online 2 October 2002 RID="a" ID="a"e-mail: bludov@ire.kharkov.ua     

Adiabatic propagation of quantized light pulses in an atomic medium with the tripod level configuration

We consider adiabatic propagation of a pair of quantized light pulses in a coherently prepared atomic medium with the tripod level configuration. We find that under conditions of electromagnetically induced transparency, two distinct polariton modes are simultaneously formed in the medium. These polaritons, represented by certain coherent superpositions of the quantized fields, have different group velocities; the fast one propagates at essentially the speed of light, while the group velocity of the slow polariton can be dynamically reduced to zero. The state mapping between the electromagnetic field and atomic ensemble is also demonstrated. The text was submitted by the author in English.     

Bloch oscillations of quasispin polaritons in a magneto-optically controlled atomic ensemble

We consider the propagation of quantized polarized light in a magneto-optically-manipulated atomic ensemble with a tripod configuration. A polariton formalism is applied when the medium is subjected to a washboard magnetic field under electromagnetically-induced transparency. The dark-state polariton with multiple components is achieved. We analyze the quantum dynamics of the dark-state polariton using experimental data from the rubidium D1-line. It is found that one component propagates freely, however the wave packet trajectory of the other component performs Bloch oscillations.     

Photonic Thermal Rectification with Composite Metamaterials

We demonstrate strong photonic thermal rectification effect between polar dielectrics plate and the composite metamaterials containing nonspherical polar dielectric nanoparticles with small volume fractions.Thermal rectification efficiency is found to be adjusted by the volume fractions and the nanoparticles’shape,and it can be as large as 80%when the polar dielectric nanoparticles are spherical in shape and are in the dilute limit with the volume fraction f=0.01.Physically,there exists strong electromagnetic coupling between the surface phonon polariton mode of polar dielectrics plate and the localized surface phonon polariton mode around polar dielectric nanoparticles.The results provide alternative new freedom for regulating energy flow and heat rectification efficiency in the near field,and may be helpful for design of multiparameter adjustable thermal diodes.     

Analysis of surface and guided wave plasmon polariton modes in insulator–metal–insulator planar plasmonic waveguides

Theoretical and experimental study of the surface plasmon–polariton and guided wave plasmon polariton modes is presented for the Sapphire/Ag/Polycarbonate/Air structure. Theoretical results are obtained by solving complex multilayer eigenvalue equations as well as the reflectivity equation for this structure. It is proposed that the mode attenuation can be significantly reduced by inserting a low index dielectric buffer between the metal and the guiding dielectric layer. The dispersion and attenuation curves are generated. Both the surface plasmon and guided wave plasmon polariton modes are studied experimentally. The experimental values of the effective refractive indices agree well with the theoretical values. The electric field profiles are generated and used to examine the nature of modes. After optimization of various parameters the condition for low loss single mode guiding is obtained for the proposed structure. Effect of metal thickness on surface plasmon mode is also discussed. It is inferred that in a properly optimized plasmonic waveguide, the losses can be reduced by a factor of 4.     

Center-of-mass quantization of excitons and Fabry–Perot modes of the polariton in ZnSe epilayers

Reflectance properties of ZnSe epilayers grown on GaAs substrates are studied at 80 K. Oscillation features are observed in the region of exciton resonance which are significantly different depending on the epilayer thickness L. For optically thin layers with thickness in the range of several tens of nanometer, reflectance oscillations appear above the light-hole (lh) exciton, while for optically thick layers with thickness in the range of a micrometer, reflectance oscillations appear between 1s and 2s excitons. These oscillations are interpreted as the quantized levels of the exciton center-of-mass motion in the lower branch of the polariton for optically thin layers and Fabry–Perot modes in the upper branch of the polariton for optically thick layers, respectively. The reflectance data are analyzed in the frame work of a dielectric function with a polariton dispersion.     

Van der Waals interactions between atoms and dispersive surfaces at finite temperature

The long-range interactions between an atomic system in an arbitrary energy level and dispersive surfaces in thermal equilibrium at non-zero temperature are revisited within the framework of the quantum-mechanical linear response theory, using generalized susceptibilities for both atom and electromagnetic field. After defining the observables of interest, one presents a general analysis of the atomic level shift valid for any number and form of dielectric surfaces. It is shown that, at zero temperature, one recovers well-known results previously obtained in the linear response regime. The case of a plane dispersive surface is elaborated on in the non-retarded regime. Calculations are given in detail for a dielectric surface exhibiting a single polariton resonance. Theoretical predictions are presented within a physical viewpoint allowing one to discriminate between the various interaction processes: on one hand, the level shift induced by non-resonant quantum fluctuations, on the other hand, two potentially resonant atom-surface couplings. The first resonant process appears for excited-state atoms and originates in an atomic de-excitation channel resonantly coupled to the surface polariton mode. It exists also at zero temperature, and has been studied and observed previously. The second physical process, which exists at non-zero temperature only, corresponds to the reverse process in which a thermal quantum excitation of a surface polariton resonantly couples to an atomic absorption channel. This novel phenomenon is predicted as well for a ground state atom, and can turn the ordinary long-range van der Waals attraction of atoms into a surface repulsion at increasing temperatures. This opens the way to the control and engineering of the sign and amplitude of van der Waals forces via surface temperature adjustment.     

Optical interaction in a plasmonic metallic particle chain coupled to a metallic film

We study the coupling of localized surface plasmon and surface plasmon polariton modes in a system composed of a metallic nanoparticle chain imbedded in a dielectric–metal–dielectric substrate. The results show the influence of outside parts and imbedded parts of particles on the interaction between localized surface plasmon and surface plasmon polariton modes. An enhancement can be observed in our structure. This kind of the structure has a very promising candidate for biosensing and surface enhanced spectroscopy applications.     

A representation of Kerr-like nonlinearity for the analytical TM surface polariton solution

The TM-polarized waves propagating along the interface between a nonlinear Kerr-like material and linear cladding are investigated. We analyse the nonlinear dielectric permittivity as a function of the electromagnetic field. It is shown that an exact analytical solution of Maxwell's equations corresponding to the TM surface polariton in the form described by sech function do exist in a Kerr-like nonlinear medium with the permittivity profile given by a hypergeometric function. We compare our analytical solution and analogous exact numerical solution in a Kerr medium. The power flow down the interface between two media is also discussed.     

Theory of ferromagnetic polariton linewidths

The interaction between magnons and photons which is responsible for magnetic polariton formation is expressed in terms of second quantized operators, and it is confirmed that the polariton dispersion curve obtained by diagonalizing the Hamiltonian is the same as that found classically. A term describing relaxation of the polariton by the two magnon mechanism which is often dominant in ferromagnetic resonance is then introduced. The lineshape function for inelastic light scattering is calculated by a Greens function technique. On the assumption that the lineshape can be approximated as a Lorentzian an expression for the linewidth is derived. The linewidth is zero when the polariton frequency Ω lies outside the magnon manifold, and increases discontinuously from zero at w = ¦γ¦H₀, where H₀ is the (internal) static field.     

On the characteristics of commonly nonideal rectangular ridge dielectric-loaded surface plasmon polariton waveguides in practical fabrication processing

In this paper, four commonly nonideal structures of the ideal rectangular dielectric ridge dielectric-loaded surface plasmon polariton waveguides (DLSPPWs) in actual fabrication processing were studied. The mode effective index, propagation length, field distributions, effects of geometric deviation, lateral field confinement and figures of merit of fundamental mode were calculated at the telecommunication wavelengths. It was found that, the propagation length, the lateral field confinement and figures of merit of four nonideal rectangle ridge DLSPPWs were changed compared with the ideal rectangular dielectric ridge DLSPPW. However, the field distributions were kept, and, the characteristics of nonideal rectangle ridge DLSPPWs were affected by the geometric deviation. This study presents the characteristics of commonly nonideal rectangle ridge DLSPPWs and provides substantial information for processing and optimizing the rectangular dielectric ridge DLSPPWs in practical fabrication processing.     

Dispersion relation of LT mixed mode polaritons

Simple equations are presented for polariton dispersion relations in anisotropic medium for an arbitrary direction of wave vector, where LT (longitudinal-transverse) mixed modes occur in general. The use of the polarizability tensor defined for pure external (not for the total) field is essentially important to obtain the simple result. The relation between all the tensor components of the polarizability and dielectric function is also explicitly given. The result can be used for any elementary excitations relevant to dielectric function. In the case of multi-component excitons of LT mixed mode character, the dispersion equation is rewritten in a matrix form, which is useful to obtain the allowed values of polariton wave vector for a given frequency.     

基模磁激元诱导的多带完美吸收

本文提出一种方向不敏感多带吸收的新结构,即结合光学声子色散材料及无色散介电材料,将其作为单一尺寸金属/介质/金属微光栅的介质分离层。在红外大气窗口波段激发了基模磁激元谐振因此导致多频带吸收。基于有限元方法求解了混合结构的吸收率及电磁场分布,并研究了入射角及结构参数的变化对多峰值吸收的影响。考虑到磁激元的本质是由金属光栅下表面与金属基底上表面诱导出反向电流震荡引起,多层介质膜起到介电隔离层的作用。对多层介质膜进行等效介质理论近似,并通过等效LC电路预测和分析了基模磁激元谐振频点。本文所提出的多带吸收机理在红外探测、辐射制冷领等域具有应用前景。     

太赫兹表面极化激元

作为束缚于表面或界面的电磁波与极性元激发的耦合模量子,表面极化激元是克服衍射极限的核心物理.在紫外、可见以及近红外波段,表面等离子极化激元展现出了亚波长特性,具有高分辨成像等应用,并发展成为"表面等离子极化激元亚波长光学"学科;在中红外波段,表面声子极化激元发挥着同样的作用.太赫兹波段曾是人类认识的空白区域,近三十年来得以高速发展,其战略意义重大.具有克服衍射极限能力的太赫兹表面极化激元同样是小型化与集成化太赫兹器件,以及太赫兹超高分辨成像的重要物理基础.近几年来,对以石墨烯为代表的二维材料的研究突飞猛进,诞生了"石墨烯表面等离子极化激元亚波长光学"这门学科,并贡献于太赫兹领域.本文对可在太赫兹波段工作的人工超构材料、掺杂半导体、二维电子气、二维材料、拓扑绝缘体等结构材料的表面极化激元进行了较为全面的总结与介绍,为研制克服衍射极限的太赫兹集成光子学器件提供可资借鉴的物理基础.     

Tensor of the nonlinear polarizability of anisotropic medium and “local” field method

The nonlinear polarizability tensor (NPT) for a molecular crystal of arbitrary symmetry has been obtained within the framework of polariton theory. Use of the Göppert-Mayer unitary transformation for the Hamiltonian of the crystal plus quantized electromagnetic field system made it possible to represent finally the result for the NPT in a compact form and to compare with results of semiphenomenological calculation of the NPT and to go out of the framework of the Gaitler-London approximation.     

Dielectric waveguide model for guided surface polaritons

Although surface polariton modes supported by finite-width interfaces can guide electromagnetic energy in three dimensions, we demonstrate for the first time to our knowledge that such modes can be modeled by the solutions of two-dimensional dielectric slab waveguides. An approximate model is derived by a ray-optics interpretation that is consistent with previous investigations of the Fresnel relations for surface polariton reflection. This model is compared with modal solutions for metal stripe waveguides obtained by full vectorial magnetic-field finite-difference methods. The field-symmetric modes of such waveguides are shown to be in agreement with the normalized dispersion relationship for analogous TE modes of dielectric slab waveguides. Lateral confinement is investigated by comparison of power-density profiles, and implications for the diffraction limit of guided polariton modes are discussed.     

Enhancing surface plasmon polariton propagation by two-layer dielectric-loaded waveguides on silver surface

We report a study of a two-layer dielectric-loaded surface plasmon polariton waveguide (TDLSPPW) which consisted of two dielectric layers (high-index/low-index) on a silver film. The discontinuity of the electric field at the interfaces resulted in a concentrated field in the low-index region. It efficiently reduced the propagation loss of the surface plasmon polariton mode. The mode fields and corresponding complex propagation constants were calculated by a vector finite-difference method. The propagation properties were measured by a modified near-field optical microscope. It is confirmed that the propagation length of the proposed TDLSPPW was about 1.6 times longer than conventional single-layer SPP waveguides. In addition, a 90^° waveguide turn with 3 μm radius showed that the bending loss was smaller than 2 dB.     

Surface Plasmon Polariton Fizeaus Dragging: via Relative Rotational Sensing

A new scheme focusing on the surface plasmon polariton interferometry between the metal and dielectric interface is introduced. The phase shift is measured by using surface plasmon polariton wave, generated at the interface of metallic and dielectric media. The phase shift of SPPs is modi?ed under phase and amplitude control of complex conductivity for interferometry. The control ?elds strongly in?uence the phase shift of SPPs for detection of molecular motion. The phase shift of SPPs is further modi?ed by Plasmon polariton Fizeaus dragging effect. We measure 20%–25%fractional change in delay and their phases shift between two left and right SPPs modes. Our results may have signi?cant applications in sensor interferometer technology.     

A new class of surface magnetic TM polaritons in crystals with linear magnetoelectric effect

The conditions necessary for the formation of a new type of a surface magnetic TM polariton at the magnetic dielectric-nonmagnetic metal or the magnetic dielectric-nomagnetic dielectric interfaces are determined. The formation of a surface electromagnetic wave of this type is caused by the effect of spatial dispersion of a magnetic dielectric medium.