Tatjana Gric

Tunable surface waves at the interface separating different graphene-dielectric composite hyperbolic metamaterials

Despite the fact that metal is the most common conducting constituent element in the fabrication of metamaterials, one of the advantages of graphene over metal is that its conductivity can be controlled by the Fermi energy. Here, we theoretically investigate multilayer structures comprising alternating graphene and dielectric layers as a class of hyperbolic metamaterials for THz frequencies based on a general simple model of the graphene and the dielectric layers. By employing a method of matching the tangential components of the electrical and magnetic fields, we derive the relevant dispersion relations and demonstrate that tuning can be achieved by modifying the Fermi energy. Moreover, tunability of the graphene-dielectric heterostructures can be enhanced further by changing either the thickness of the dielectric layers or the number of graphene sheets employed. Calculated dispersion relations, propagation lengths of plasmon modes in the system are presented. This allows us to characterize and categorize the modes into two groups: Ferrel-Berreman modes and surface plasmon polaritons.

Surface-Plasmon-Polaritons at the Interface of Nanostructured Metamaterials

The rigorous modeling and analysis of surface waves at the boundary of two metamaterials are presented. The nature of the phenomenon of the surface-plasmon-polaritons and the influence of various parameters on it are investigated. We have analyzed the properties of structures incorporating nanostructured metamaterials. Surface-plasmon-polaritons at the interface of such metamaterials are studied. We demonstrate the ways to control the properties of the surface waves. Each metamaterial comprises alternating metal and dielectric layers. We analyze the dependence of the dispersion characteristics on the materials employed in metal-dielectric compound. The consistency of the dispersion diagrams and effective permittivity is studied. The Drude model is introduced in the metal dispersion in order to take into account the effects of the structure on dielectric properties.

Spoof plasmons in corrugated semiconductors

We report on a theoretical investigation of the dispersion relation of surface plasmon polaritons (SPPs) on a periodically corrugated semiconductor surface. We assumed Drude’s permittivity model of the semiconductor, which accurately describes the loss of these spoof SPPs. In the THz frequency range, the properties of the dispersion and loss of spoof SPPs on corrugated Si surfaces are studied. A low-loss propagation of spoof SPPs can be achieved by an optimum design of the surface structure. It was found that by increasing the lattice constant or by reducing the groove depth, the investigated structure can provide a low guiding attenuation.

Spoof plasmons in corrugated transparent conducting oxides

Abstract Nowadays, there is a need to search for better materials aimed for plasmonic and metamaterial applications. Transparent conducting oxides (TCOs) are known as low-loss plasmonic materials in the near-infrared wavelength range. The further design of the lower loss materials would be available by fulfilling a more sophisticated theoretical study. In this work, we address the spoof plasmons on a periodically corrugated surface made of the TCOs. We assumed the Drude–Lorentz’s permittivity model of the semiconductor, which accurately describes the loss of these spoof surface plasmon polaritons (SPPs). In the THz frequency range, the properties of the dispersion and loss of spoof SPPs on corrugated ZnO and indium tin oxide surfaces are studied. A low-loss propagation of spoof SPPs can be achieved by an optimum design of the surface structure. Moreover, it was found that the low guiding attenuation can be achieved by employing the TCOs.

Controlling hybrid-polarization surface plasmon polaritons in dielectric-transparent conducting oxides metamaterials via their effective properties

Diversiform hybrid-polarization surface plasmon polaritons (HSPPs) at metamaterial (MM)–dielectric interfaces have initially been predicted by theoretical considerations based on dispersion equations. Here, we discuss hybrid HSPPs at the interface between (1) transparent conducting oxide (TCO)/dielectric MMs and TCO or (2) MMs and dielectrics through a detailed numerical analysis based on a Drude-Lorentz model for the permittivity of the TCO-layer. We show that the introduction of a MM/TCO interface leads to a transformation of the traditional-like SPPs. As a consequence, the new types of surface waves are found, and we reveal the existence of a new type of surface wave which is closely related to the presence of the TCO layers in the MM structure.

Challenge of inhomogeneous waveguides analysis

Optical waveguides have been a subject of an intensive theoretical research, resulting in applications in several fields, and stimulated research in integrated optics. Homogeneous dielectric waveguides and their properties are covered in detail in many articles and textbooks. However, in waveguides loaded with arbitrary inhomogeneous dielectrics, analytical solutions are possible only for a limited number of permittivity profiles in simple geometries. The analysis of longitudinally inhomogeneous waveguides has been already proposed, but the main drawback of this approach is that it requires cumbersome and time-consuming integration. We therefore suggest to take this a step further by applying our new original analytical approach that does not require integration. The aim of this work is to establish a different method that is generally applicable to any vectorial time-dependent, anisotropic, non-linear, inhomogeneous, dissipative and dispersive media to analyze the field distribution of inhomogeneous 1-D and 2-D waveguides with symmetric and asymmetric permittivity profiles. Our initial consideration of slab problems with arbitrary profiles by means of analytical method shows a great deal of potential for use in applications in fields such as physics, and engineering.

Electrodynamical Analysis of Open Lossy Metamaterial Waveguide and Scattering Structures

Large stream of articles devoted to the study of metamaterial waveguide and metamaterial scattering (reflecting) structures points that there is a need for development devices possessing unique characteristics, as multifunctionality, reconfigurability, certain frequency bandwidth, ability to operate at high-powers and high-radiation conditions. The importance of diffraction problems for scattering structures is based on their great practical utility for many applications, such as reflector antennas, the analysis of structures in open space, electromagnetic (EM) defence of structures, the scattering modeling for remote sensing purposes, high frequency telecommunications, computer network, invisibility cloaks technology and radar systems (Li et.al., 2011; Zhou et.al.; 2011, Zhu et al., 2010; Mirza et al., 2009; Abdalla & Hu, 2009; Engheta & Ziolkowski, 2005).

Surface plasmon polaritons in nanostructured metamaterials

The fundamental performance limits of coherent optical transmission systems can be observed by a simple optimization between the linear noise and the nonlinear noise generated within the system. Optical Phase Conjugation (OPC) is considered to be one of the promising techniques to compensate for optical fiber’s dispersion and nonlinearity that cause crosstalk between signals traveling through long-haul optical transmission systems, nonlinearity compensation can lead to significant information capacity and distance reach expansion of optical fiber transmission links. To get the full benefit from the deployment of OPC in optical transmission systems, a few considerations must be taken into account, such as: power profile symmetry, fiber’s dispersion slope and Polarization Mode Dispersion (PMD). In this contribution, we will present our simplified theoretical predictions of optical fiber transmission systems performance that deploy mid-link OPC and multiOPC and we will show that the introduction of multi-OPC in an optical transmission system will minimize the impact of uncompensated/nondeterministic signal-signal nonlinear interactions due to fiber’s PMD and signal-noise interactions. We will show wide range of simulation and experimental results that validate the theoretical predictions of system’s performance for various types of links: dispersion managed, dispersion unmanaged, discretely amplified systems and distributed Raman amplified systems. Also, we will present an extensive experimental study shows that the deployment of mid-link OPC can provide a significant reach improvement in asymmetric lumped optical fiber links when optimizing the span length.III-V semiconductors have a direct bandgap that can be tuned through alloy engineering and therefore appear as very interesting for solar-cells, solid-state lighting and high power applications. The performances of current devices may be increased through the use of nanostructures and nanowires which look promising for the integration of high efficiency devices. Nanowires exhibit great properties such as efficient strain relieving capability and large specific area. Growth on silicon substrates and core-shell structures can be considered as well. Still, the production of nanowire-based devices faces material challenges related to morphological, structural, optical and electrical properties which are very linked to the synthesis process. This presentation will focus on Hydride Vapor Phase Epitaxy, which is a growth process implemented in a hot wall reactor using chloride precursors, and showing unique features regarding the growth of III-V and III-Nitride nanowires. For example, self-catalyzed GaAs nanowires were grown on silicon at a fast growth rate (60 µm.h-1) exhibiting a constant zinc-blende crystalline phase, for the potential fabrication of GaAs-based photonic devices on Si. For III-Nitride materials, InGaN nanowires demonstrating the entire composition range were grown by using a method compatible with the standard GaCl-based GaN growth process. Photoluminescence coupled with transmission electron microscopy measurements showed that these nanowires could overcome the so-called green gap and stretch the limits of solar cells efficiency. By taking advantage of the large growth rates anisotropy resulting from the use of chloride precursors, we could freely tuned the shape of GaN wires on masked substrates with (sub)-micrometric apertures.W the popularization of data centre and other bandwidth hungry inter-connect applications, the desired capacity of short reach optical network has exponentially increased to 400 Gbit/s or even more. Recent standardization efforts for 400 G intradata center connections specify link lengths of up to 2 km. 8×56 Gb/s or 4x100 Gb/s could enable such 400 G networks. Relative to coherent detection. Intensity modulation/direct detection (IM/DD) is a good candidate in inter-connect due to its low cost. For 56 and up to 100 Gb/s signal generation, a few modulation formats or schemes, such as pulse-amplitude-modulation (PAM4), discrete multitone (DMT), duobinary and chirp-managed laser (CML) are proposed and experimentally demonstrated. However, considering cost, size and power comsuption, the modulation format should be optimized for different networks to meet different requirements. In this talk, we will discuss this issue how to optimize the modulation formats for different optical networks?

Three-layered nanostructured metamaterials for surface plasmon polariton guiding

A novel metamaterial (MM) to guide surface plasmon polariton (SPP) is considered. Specific example of three-layered nanostructured MM and its dispersion engineering are studied in details allowing the development of new devices. Herein we deal with the general original concept of MMs based on inclusions of the additional layers as with a promising class of materials. The metal material stands for as the limiting factor of the frequency range that SPP mode exists. It is worthwhile noting that the SPP mode at high frequency is characterized by extremely large loss. The former restriction causes serious limitations for the potential applications of SPP in the field of optical interconnection, active SPP devices and so on. The surface mode guided by dielectric/graphene/dielectric multilayers MM has been studied based on the theory of electromagnetic field aiming to extend the frequency range of SPP mode. It is demonstrated that surface mode could be supported by the MM. Moreover, the frequency range to where conventional metal SPP cannot exist is extended. Herein, it is concluded that, the MM guided SPP mode can potentially be used to enhance the plasmonic performance over traditional metal one by varying the structure parameters.

Surface waves supported by the nanostructured semiconductor metamaterials

Abstract We discover a new kind of surface wave on semiconductor nanostructured metamaterial, which crosses the light line with a substantial portion at lower frequencies lying above the free space light line. Interestingly, the propagation of such surface wave is found to be sensitive to the parameters of the semiconductor. Furthermore, the Ferrel-Berreman modes are observed under the certain conditions, opening a gateway toward device fabrications.