[Show abstract][Hide abstract] ABSTRACT: We discuss the propagation of electromagnetic waves through a one-dimensional periodic array of bilayers with metal inclusions. We show that the nonlocality of metal conductivity leads to the emergence of the fundamental collisionless Landau damping. It cannot be neglected, not only when prevailing over ordinary collision damping, but even when these two kinds of electromagnetic absorption are of the same order. Landau damping always exists and considerably alters the photonic transmission of the array within the THz and near-infrared frequency range.
[Show abstract][Hide abstract] ABSTRACT: On the basis of the formalism of the Boltzmann kinetic equation for the distribution function of the conduction electrons, the photonic band structure of binary dielectric-metal superlattice is theoretically studied. Using the constitutive nonlocal relation between the electrical current density and the electric field inside the metallic layer, the dispersion equation for photonic eigenmodes in the periodic stack is analytically expressed in terms of the surface impedances at the interfaces of the metal and dielectric layers. In the case of very thin metallic layers, the optic spectrum for the superlattice exhibits narrow pass bands as a result of the strong contrast between the impedances of the dielectric and the metal. The narrow pass bands are attributed to Fabry-Perot resonances in the relatively-thick dielectric layer. The metal nonlocality is well pronounced in the infrared and, therefore, the nonlocal effect upon the photonic band structure of the superlattice can be strong when the Fabry-Perot resonance bands are in that frequency range. Our results for the photonic spectrum have been compared with those obtained within the local Drude-Lorentz model. Noticeably differences not only in the the magnitude, but also in the sign of the real part of the Bloch wave number in the Fabry-Perot resonance bands, have been found.
[Show abstract][Hide abstract] ABSTRACT: We theoretically investigate the optical properties of one-dimensional photonic crystals composed of two alternating layers, namely a semiconductor film and a metallic one. The nonlocal optical response of the semiconductor is here described by using a resonant excitonic dielectric function, whereas the local response function of the metal film is modeled with Drude formula. We calculate optical spectra of the metal–semiconductor 1D photonic crystal for both s- and p-polarization geometries. In both cases the spectra exhibit a rich resonance structure due to the coupling of size-quantized excitons inside the semiconductor film with light. We show the difference between s- and p-polarization reflectivity as the angle of incidence is increased. In the p-polarization geometry, besides transverse exciton-polariton modes, longitudinal polarization waves are excited producing additional spectral resonances. The spectra become radically different when the frequency corresponding to the minimum of the first photonic pass-band is close to the exciton resonance, since such a frequency is distinct for s- and p-polarized modes. We also show how reflectivity spectra for both polarizations are modified with varying the metal filling fraction which controls the width of the gap below the lowest frequency band.
Photonics and Nanostructures - Fundamentals and Applications 01/2012; 10(1):69–82. DOI:10.1016/j.photonics.2011.07.003 · 1.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We theoretically investigate the coupling of light with magnetoexcitons in near-surface quantum wells under the action of a static electric field parallel to the well plane. Such a coupling is here described within the Stahl’s real-space density-matrix approach. In particular, we have solved the system of equations for the coherent-wave amplitude and the electromagnetic fields for InGaAs/GaAs quantum-well heterostructures and calculated their reflectivity spectra. We have found that a parallel electric field of magnitude ∼ 1–10 kV/cm can considerably alter the line shape of optical spectra due to the resonant coupling of light with magnetoexcitons having nonzero angular momentum projection. Besides, we have studied the changes in the profile of the optical spectra as the thickness of the heterostructure cap layer is decreased until it is comparable with the exciton radius and, consequently, the interaction of the magnetoexciton with the sample surface becomes strong.
[Show abstract][Hide abstract] ABSTRACT: We have derived simple analytical expressions for the frequency-dependent effective permittivity tensor of a one-dimensional metal-dielectric photonic crystal in the long wavelength limit. Our results describe the transition between the regime, described by Rytov's formulas for sufficiently long waves, and that predicted by Xu et al. [6], where the effective plasma frequency is independent of the metallic-layer parameters. The derived expressions can be useful for determining the frequency intervals where such an anisotropic system can exhibit metamaterial behavior.
Progress In Electromagnetics Research Letters 01/2011; 22.
[Show abstract][Hide abstract] ABSTRACT: Exact analytic formulas for calculating the effective permittivity, permeability, and crossed magnetoelectric tensors for photonic crystals in the long-wavelength limit are presented. The formulas are valid for arbitrary Bravais lattice and form of inclusions, which can be dielectric, magnetic, or chiral. We have applied them to study the optical anisotropy of homogenized magnetodielectric three-dimensional photonic crystals, which can be induced by the type of Bravais lattice or the form of the inclusion even in the case when the photonic crystal is composed of isotropic materials. It is established that the electromagnetic modes, propagating in such anisotropic magnetodielectric metamaterials, are extraordinary, unlike the modes in homogenized nonmagnetic dielectric composites, where at least one mode is ordinary.
[Show abstract][Hide abstract] ABSTRACT: We investigate theoretically the coupling of exciton with light in a one-dimensional photonic crystal. The unit cell of the crystal consists of two alternating layers, namely a metallic layer and a semiconductor one. The frequency-dependent dielectric function of the metal is described by the Drude model, whereas for the semiconductor we use a nonlocal excitonic dielectric function. The polariton dispersion for s-polarized modes in the metal-semiconductor photonic crystal is compared with that for a dielectric-semiconductor photonic crystal. Because of the metal layers, a low-frequency gap appears in the photonic band structure. The presence of the semiconductor gives rise to photonic bands associated with the coupling of light with size-quantized excitón states. At frequencies above the longitudinal exciton frequency, the photonic band structure exhibits anticrossing phenomena produced by the upper exciton-polariton mode and size-quantized excitons. It is found that the anticrossing phenomena in the metal-semiconductor photonic crystal occur at higher frequencies in comparison with the dielectric-semiconductor case.
Journal of Nanoscience and Nanotechnology 01/2009; 8(12):6584-8. · 1.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The optical properties of exciton polaritons in one-dimensional photonic crystals are theoretically investigated. The periodic photonic struc- ture is formed by two alternating layers, namely a local dielectric layer and a thin semiconductor one which is characterized by a nonlocal excitonic dielectric function. We calculate reflectivity spectra for one-dimensional MgO-CuCl photonic crystals, which exhibit a rich res- onance structure because of the optical manifestation of size-quantized excitons. We study the changes in the resonance structure as the thickness of the thin semiconductor layer is varied. It is found that odd quantized-exciton modes are well manifest in the optical spectra in comparison with even states. We have also investigated the effect of both homogeneous bulk damping and interface-induced broadening upon the reflectivity resonances. The broadening due to interface disorder is calculated with the self-consistent Green's function method.
Revista Mexicana de Fisica 01/2008; 54. · 0.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We present a theoretical study of the optical properties of excitons in symmetric and asymmetric bulk and near-surface double quantum wells (DQWs) under the action of an external magnetic field oriented along the growth direction. The coupling of magnetoexcitons with light in the semiconductor heterostructure is described with Stahl’s real-space density-matrix approach. After solving the system of equations for the coherent wave amplitude and the electromagnetic fields, we calculate optical spectra (reflectivity and absorption) for specific GaAs/AlGaAs DQWs. Our results for the absorption of bulk symmetric DQWs are compared with those obtained by Vera and Barticevic [F. Vera and Z. Barticevic, J. Appl. Phys. 83, 7720 (1998)]. The effect of the surface-magnetoexciton interaction upon the reflectivity and absorption for near-surface DQWs is analyzed. It is established that such an interaction alters the symmetry or asymmetry of the DQWs, and therefore, the resonance structure of their optical spectra is noticeably modified as the thickness of the cap layer is reduced.
[Show abstract][Hide abstract] ABSTRACT: The spectral properties of metal-dielectric and metal-semiconductor 1D photonic crystals (PCs) are theoretically investigated, considering spatial dispersion in the metal and in the semiconductor, respectively. In the case of 1D PCs, composed of alternating metallic and dielectric slabs, we apply the classical fonnalism of the Boltzmann's kinetic equation for the distribution function of the conduction electrons in order to determine the nonlocal constitutive equation for the metallic slabs. Afterwards, we calculate the dispersion relation for the bulk modes in the 1D PC and compare it with that obtained within the Drude-Lorentz model, which is implicitly local. Another kind of nonlocal effects are studied by considering a metal-semiconductor 1D PC. In this case, the frequency-dependent dielectric function of the metallic component is described by the local Drude-Lorentz model, whereas for the semiconductor we use a Hopfield-Thomas dielectric function, which describes its nonlocal behavior near exciton resonance. The polariton dispersion curves for s-polarized modes in the metal-semiconductor photonic crystal are compared with those for a metal-dielectric PC. Because of the coupling of light with excitons, which undergo size quantization inside the thin semiconductor slabs, many photonic small bands appear. We study the changes in the photonic dispersion curves for the resonant 1D PC as the filling fraction of the metal is varied.
Physics and Engineering of Microwaves, Millimeter and Submillimeter Waves and Workshop on Terahertz Technologies, 2007. MSMW '07. The Sixth International Kharkov Symposium on; 07/2007
[Show abstract][Hide abstract] ABSTRACT: The optical response of excitons in quantum wells, close to the sample boundary and under the action of a strong magnetic field perpendicular to their plane, is investigated theoretically. Solving the system of coupled equations for the coherent electron-hole interband amplitude and the electromagnetic field, reflectivity spectra for such nanostructures are calculated. The effect of the interaction of magnetoexcitons with the sample surface on the resonance structure of reflectivity spectra is analyzed. These optical spectra are also affected by the phase change of the electromagnetic wave as it propagates in the cap layer, overlying the quantum well.
[Show abstract][Hide abstract] ABSTRACT: It is well known that a semi-infinite medium that is non-magnetic and homogeneous admits surface polaritons with TM (p)-polarization, while TE (s)-polarized surface modes do not exist. It was pointed out that s-polarized surface phonon polaritons could be guided by a suitable transition layer^1, however such waves have not been detected.Our calculations show that certain treated CdS and CdSe surfaces^2 can guide surface exciton polaritons that are s-polarized. This conclusion is supported by dispersion relations, field profiles, and Attenuated Total Reflectivity spectra. 1. V. E. Kravtsov et al., Solid State Comm. 50, 741 (1984). 2. V. A. Kiselev et al., Sov. Phys. Solid State 28, 1655 (1986); A. S. Batyrev et al., JETP Lett. 62, 408 (1995). This research was partially financed by CONACyT.
[Show abstract][Hide abstract] ABSTRACT: The influence of the surface-potential shape on exciton optical spectra for thin semiconductor films is investigated theoretically. Using a realistic model with both intrinsic and extrinsic contributions, we calculate the polarization vector and the electric field in the case of s-polarized incident light at one of the thin-film surfaces. Our analytic results are employed to study the relation between the surface potential parameters and the spectra of reflectivity and transmissivity. The generation of near-surface localized excitons and their optical manifestation are also analyzed.