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Browsing by Author "Valagiannopoulos, Constantinos"

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Achieving Anomalous Refraction with Metasurfaces Composed by Two Ordinary Dielectric Materials

Tsitsas, N. L.; Valagiannopoulos, Constantinos (Metamaterials, 2018)

The optimal parameters of a dielectric metasurface, composed of two alternating rectangular rods, are investigated so that it exhibits significant enhancement in the −1- diffracted order in the transmission region. An ...
A Double-Layer Metamaterial-Based Technique for Interference Mitigation and Shielding of Planar Microwave Structures

Papadimopoulos, Athanasios; Karamanos, Theodosios; Tsitsas, Nikolaos; Valagiannopoulos, Constantinos; Kantartzis, Nikolaos; Tsiboukis, Theodoros (2016-07)

An efficient cloaking-shielding technique based on the use of a double superstrate-layer overlay is developed in this paper for planar microstrips. The metamaterial-inspired formulation reduces considerably the induced ...
Aharonov-Bohm detection of two-dimensional magnetostatic cloaks

Valagiannopoulos, Constantinos; Askarpour, Amir Nader; Al`, Andrea (2015)

Two-dimensionalmagnetostatic cloaks, evenwhen perfectly designed tomitigate the magnetic field disturbance of a scatterer, may be still detectable with Aharonov-Bohm (AB) measurements, and therefore may affect quantum ...
Analytical investigations of ground modifications assisting the detection of buried object

Valagiannopoulos, Constantinos; Tsitsas, Nikolaos L.; Sihvola, Ari H. (Nazarbayev University School of Science and Technology, 2016-08-18)

A ground-penetrating radar (GPR) antenna excites a perfectly electric conducting inclusion buried inside the ground. The scattering problem is solved semi-analytically via integral equation techniques. The permittivity and ...
Anomalous reflection of visible light by all-dielectric gradient metasurfaces

Tsitsas, Nikolaos L.; Valagiannopoulos, Constantinos (Journal of the Optical Society of America B, 2017-03-15)

Plane wave scattering by a planar metasurface composed of two periodically alternating rectangular dielectric rods is considered. A rigorous integral equation methodology is employed for the analysis and the accurate ...
Breaking the black-body limit with resonant surfaces

Valagiannopoulos, Constantinos; Simovski, Constantin R.; Tretyakov, Sergei A. (EPJ Applied Metamaterials, 2017)

The speed with which electromagnetic energy can be wirelessly transferred from a source to the user is a crucial indicator for the performance of a large number of electronic and photonic devices. We expect that ...
Conjugately-Matched Uniaxial Metamaterials Make Extremely Efficient Absorbers, Emitters, and Reflectors

Valagiannopoulos, Constantinos; Simovski, C. R.; Tretyakov, Sergei A. (2016-09)

The speed with which electromagnetic energy can be wirelessly transferred from a source to the user is a crucial parameter for performance of a large number of electronic and photonic devices. In this presentation we ...
Epsilon-near-zero behavior from plasmonic Dirac point: Theory and realization using two-dimensional materials

Mattheakis, Marios; Valagiannopoulos, Constantinos; Kaxiras, Efthimios (Physical Review B. American Physical Society, 2016)

The electromagnetic response of a two-dimensional metal embedded in a periodic array of a dielectric host can give rise to a plasmonic Dirac point that emulates epsilon-near-zero (ENZ) behavior. This theoretical result ...
Giant enhancement of the controllable in-plane anisotropy of biased isotropic noncentrosymmetric materials with epsilon-negative multilayers

Valagiannopoulos, Constantinos; Tsitsas, N. L.; Lakhtakia, A. (Journal of Applied Physics, 2017)

Giant in-plane anisotropy can be exhibited by a finitely thick periodic multilayer comprising bilayers of an isotropic noncentrosymmetric material and a non-dissipative isotropic medium of negative permittivity, when a ...
Guessing the Texture of Magnetic Samples Assisted by Aharonov-Bohm Effect

Valagiannopoulos, Constantinos; Alu, A.; Dimakis, A.; Marengo, E. A. (IEEE, 2016)

Aharonov-Bohm (AB) effect is a very significant phenomenon of quantum mechanics. It demonstrates the significance of electromagnetic potentials (proportional to fluxes) against the electromagnetic fields through the ...
Highly selective transmission and absorption from metasurfaces of periodically corrugated cylindrical particles

Tagay, Zhenisbek; Valagiannopoulos, Constantinos (Physical review B, 2018-09-25)

Gratings of infinite wires make, perhaps, the simplest class of metasurfaces, which, however, are utilized for a variety of different objectives in wave manipulation. Importantly, due to their analytical solvability, ...
Judicious distribution of laser emitters to shape the desired far-field patterns

Valagiannopoulos, Constantinos; Kovanis, Vassilios (PHYSICAL REVIEW A, 2017-06-06)

In this paper, motivated by such trends in coupled optical oscillators and applied mathematics methods, we inject an inverse-design approach in the construction of the far field of multiple radiating optical apertures. ...
Lateral radiative forces exerted by evanescent fields along a hyperbolic metamaterial slab

Nefedov, I. S.; Shalin, A. S.; Valagiannopoulos, Constantinos (Journal of Physics, 2018)

We show and investigate the optical forces acting on a particle in the vicinity of a planar waveguide which is lled with hyperbolic material and supports propagation across its plane (two-dimensional). The anisotropy ...
Magnified imaging based on non-Hermitian nonlocal cylindrical metasurfaces

Savoia, Silvio; Valagiannopoulos, Constantinos; Monticone, Francesco; Castaldi, Giuseppe; Galdi, Vincenzo; Al`u, Andrea (PHYSICAL REVIEW B. American Physical Society, 2017)

We show that a cylindrical lensing system composed of two metasurfaces with suitably tailored non-Hermitian (i.e., with distributed gain and loss) and nonlocal (i.e., spatially dispersive) properties can perform ...
Manipulating polarized light with a planar slab of black phosphorus

Valagiannopoulos, Constantinos; Mattheakis, Marios; Shirodkar, Sharmila N; Kaxiras, Efthimios (Journal of Physics Communications, 2017-11-08)

Wave polarization contains valuable information for electromagnetic signal processing; thus, the ability to manipulate it, can be extremely useful in modeling photonic devices. In this work, we propose designs comprised ...
Mitigating Snell’s-Law Reflection and Transmission with Metasurfaces of Ordinary Dielectrics

Tsitsas, N. L.; Valagiannopoulos, Constantinos (IEEE, 2017)

Obtaining anomalous reflection and transmission (namely propagation along directions different from those predicted by Snell’s law) is investigated for plane waves impinging on a planar periodic metasurface composed of two ...
Multi-mode Waveguides with Tailored Dispersion - a Way for Coherent and Dispersion-Free Propagation of Classical and Quantum Optical Signals

Valagiannopoulos, Constantinos; Mandilara, A.; Moiseev, S. A.; Akulin, V. M. (arXiv, 2017-01-12)

We show how by a tailored breaking of the translational symmetry in waveguides and optical bers one can control chromatic dispersions of the individual modes at any order and thereby overcome the problem of coherent ...
Nonlinear waves in hyperbolic metamaterials: focus on solitons and rogues

Boardman, A.D.; Grimalsky, V.V.; Guo, T.; Kibler, B.; McNiff, J.; Nefedov, I.; Rapoport, Y.; Argyropoulos, C.; Valagiannopoulos, Constantinos (Nazarbayev University School of Science and Technology, 2018-05-07)

The investigation of hyperbolic metamaterials, shows that metal layers that are part of graphene structures, and also types I and II layered systems, are readily controlled. Since graphene is a nicely conducting sheet it ...
Optical PT-Symmetric Counterparts of Ordinary Metals

Valagiannopoulos, Constantinos (IEEE Journal of Selected Topics in Quantum Electronics, 2015)

How one can fabricate the Parity-Time (PT) symmetric siblings of commonly used metals in the visible? This work tries to give an answer to that question by providing the features of the active media which conjugately ...
Optimized Operation of Photonic Devices With Use of Ordinary Bulk Materials

Valagiannopoulos, Constantinos (Metamaterials, 2018)

Structural boundaries, materials and feeding sources are the three fundamental segments defining photonic devices. Since excitation is usually dictated by the application and there are infinite ways to select the spatial ...