M. Wegener

Bio: M. Wegener is an academic researcher. The author has contributed to research in topics: Metamaterial & Metamaterial antenna. The author has an hindex of 1, co-authored 1 publications receiving 24 citations.

Photonic Metamaterials

Abstract: We review some of our recent results on photonic metamaterials operating at optical frequencies. In a series of interferometric pulse propagation experiments on negative index metamaterials, we have demonstrated simultaneous negative phase and group velocity of light at 1.5 mum wavelength. By optimizing the structure parameters and utilizing silver instead of gold, the losses of the negative index metamaterial have been reduced significantly. Further downscaling of the lattice constant has brought the negative refractive index to the red end of the visible spectrum. We have also fabricated negative index metamaterials with up to three functional layers. Besides of unusual dispersion properties, metamaterials can also exhibit very interesting polarization effects. We have performed experiments and numerical calculations for a chiral planar metamaterial design. This design comprises dense arrays of double-layer gammadions. The excitation of anti-symmetric current oscillations in the two layers leads to pronounced circular dichroism.

Phase-change materials for non-volatile photonic applications

Abstract: Materials whose optical properties can be reconfigured are crucial for photonic applications such as optical memories. Phase-change materials offer such utility and here recent progress is reviewed. Phase-change materials (PCMs) provide a unique combination of properties. On transformation from the amorphous to crystalline state, their optical properties change drastically. Short optical or electrical pulses can be utilized to switch between these states, making PCMs attractive for photonic applications. We review recent developments in PCMs and evaluate the potential for all-photonic memories. Towards this goal, the progress and existing challenges to realize waveguides with stepwise adjustable transmission are presented. Colour-rendering and nanopixel displays form another interesting application. Finally, nanophotonic applications based on plasmonic nanostructures are introduced. They provide reconfigurable, non-volatile functionality enabling manipulation and control of light. Requirements and perspectives to successfully implement PCMs in emerging areas of photonics are discussed.

Multilayer System of Lorentz/Drude Type Metamaterials with Dielectric Slabs and its Application to Electromagnetic Filters

Abstract: MULTILAYER SYSTEM OF LORENTZ/DRUDE TYPEMETAMATERIALS WITH DIELECTRIC SLABS AND ITSAPPLICATION TO ELECTROMAGNETIC FILTERSC. SabahPhysikalisches InstituteJohann Wolfgang Goethe UniversityMax-von-Laue-Strasse 1, D-60438, Frankfurt am Main, GermanyS. UckunElectrical and Electronics Engineering DepartmentUniversity of GaziantepGaziantep 27310, TurkeyAbstract—In this work, frequency behavior of the multilayerstructure comprised of double-negative (DNG) and dielectric slabs ispresented in detail. The multilayer structure consists of

Non-linear waves in lattices: past, present, future

Abstract: In the present work, we attempt a brief summary of various areas where non-linear waves have been emerging in the phenomenology of lattice dynamical systems. These areas include non-linear optics, atomic physics, mechanical systems, electrical lattices, non-linear metamaterials, plasma dynamics and granular crystals. We give some of the recent developments in each one of these areas and speculate on some of the potentially interesting directions for future study.

Superconducting Metamaterials

Abstract: Metamaterials (MMs), i.e. artificial media designed to achieve properties not available in natural materials, have been the focus of intense research during the last two decades. Many properties have been discovered and multiple designs have been devised that lead to multiple conceptual and practical applications. Superconducting MMs have the advantage of ultra low losses, a highly desirable feature. The additional use of the Josephson effect and SQUID configurations produce further specificity and functionality. SQUID-based MMs are both theoretically investigated but also fabricated and analyzed experimentally in many labs and exciting new phenomena have been found both in the classical and quantum realms. The SQUID is a unique nonlinear oscillator that can be manipulated through multiple external means. This flexibility is inherited to SQUID-based MMs, i.e. extended units that contain a large arrangement of SQUIDs. Such an assembly of weakly coupled nonlinear oscillators presents a nonlinear dynamics laboratory where numerous complex spatio-temporal phenomena may be explored. We focus primarily on SQUID-based MMs and present basic properties related to their individual and collective responses to external drives. We start by showing how a SQUID-based system acts as a genuine MM, demonstrate that the Josephson nonlinearity leads to wide-band tunability, intrinsic nonlinear as well as flat band localization. We explore further properties such as multistability and self-organization and the emergence of chimera states. We then dwell into the truly quantum regime and explore the interaction of electromagnetic pulses with superconducting qubits where the coupling between the two yields self-induced transparency and superradiance. We thus attempt to present the rich behavior of coupled superconducting units and point to their basic properties and practical utility.

Interaction between graphene and metamaterials: split rings vs. wire pairs.

Abstract: We have recently shown that graphene is unsuitable to replace metals in the current-carrying elements of metamaterials. At the other hand, experiments have demonstrated that a layer of graphene can modify the optical response of a metal-based metamaterial. Here we study this electromagnetic interaction between metamaterials and graphene. We show that the weak optical response of graphene can be modified dramatically by coupling to the strong resonant fields in metallic structures. A crucial element determining the interaction strength is the orientation of the resonant fields. If the resonant electric field is predominantly parallel to the graphene sheet (e.g., in a complementary split-ring metamaterial), the metamaterial's resonance can be strongly damped. If the resonant field is predominantly perpendicular to the graphene sheet (e.g., in a wire-pair metamaterial), no significant interaction exists.