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EN
In present paper, a tunable left-handed plasmonic nanoantenna is designed to attain ultraviolet emission through a second harmonic generation with a phase harmonic condition. For the devised structure, the dispersion properties and negative values of the magnetic permeability and the electric permittivity show that the designed structure is left-handed for the primary wave (red light) and right-handed for the second harmonic wave (ultraviolet light). The 3D finite-difference time-domain method is employed to reveal its nonpareil skills (i.e. immense left-handed transmission efficiency and far-field spectrum exhibiting directionality). Attained results by numerical calculation for the second harmonic generation are accomplished with finite-difference time-domain analysis. The impact of physical parameters on transmission and dispersion characteristics is also scrutinized. Furthermore, flat lens application for a red light region with a centered wavelength at λ = 650 nm from the guileless design of LHM with no aberration is triumphed. Ultimately, a multifunction left-handed material is designed revealing tremendous potential to amass and abridge future applications in one architecture.
EN
The negative refractions are discussed in detail to demonstrate two different two-dimensional photonic crystal structures that undergo negative refractions associated with the backward-wave and forward-wave phenomenon, respectively. The presentation of the left-handed property of effective negative index photonic crystal is followed by a discussion of a backward flowing phase and causality. The forward-wave negative refraction occurs in photonic crystals as a result of anisotropy. This paper is based on the theoretical analysis and is illustrated with the results of finite element method simulations.
EN
In this paper, we study propagation of electromagnetic wave in negative ternary refractive indices of two-dimensional photonic crystals. We consider two structures with two concentric cylindrical rod and shell in which one of them has negative refractive indices, in positive dielectric background. It is shown that by increasing the diameter of the rod in both structures, we can obtain more and wider band gaps in comparison with the structures in which there is no negative refractive index materials. This increase is more considerable in the first structure, in which the rod has a negative refractive index, in comparison with the second one, where the rod has a positive refractive index.
EN
A new design of a broad angle photonic crystal polarization beam splitter (PhC-PBS) with frequency tunable index of refraction, i.e. varying from positive to negative, is presented. Designed PhC-PBS shows transition from right-handed medium (positive index medium) to left-handed medium (negative index medium) with change in normalized frequency from 0.437 to 0.516. The design description includes band structure calculations and equi-frequency contour (EFC) analysis, where direction of refraction is tuned by the frequency and thickness of a slab. The proposed PBS splits transverse electric (TE) polarization in negative direction and transverse magnetic (TM) polarization in positive direction for optical communication windows in the range of 1.31 žm and 1.55 žm. Finite difference time domain (FDTD) method is employed to evaluate left-handed, right-handed transmission and reflection characteristics. High transmission and extinction ratio at wide range of incident angles validate proposed design as an efficient and broad angle PBS based on tunable negative refraction. Demonstration of near- and far-field resonance patterns reveals that proposed structure has the high potential in the design and development of the multiple photonic device applications, i.e., highly directional optical antennas also.
5
Content available remote Negative refraction of photonic and polaritonic waves in periodic structures
EN
Negative refraction can be achieved in photonic crystals. We briefly summarize recent studies in this field, and show that such effects are also possible in polaritonic and plasmonic structures, such as the dipole crystal. We propose a practical realization of this crystal, a periodic lattice of dielectric spheres. We study its mode structure, and preliminary results demonstrate the negative refraction on a polaritonic band.
6
Content available remote Towards focusing using photonic crystal flat lens
EN
We report on the numerical simulation and fabrication of a two-dimensional flat lens based on negative refraction in photonic crystals. The slab acting as a lens is made of an hole array (operating at the wavelength of 1.5 µm) etched in a InP/InGaAsP/InP semiconductor layer. We first study the key issues for the achievement of a negative refractive index taking advantage of folding of dispersion branches with main emphasis in dispersion properties rather than the opening of forbidden gaps. The diffraction and refraction regimes are analysed according to the comparison of the wave-vector with respect to the relevant dimensions of the hole array. In the second stage, we illustrate technological challenges in terms of e-beam lithography on a sub-micron scale and deep reactive ion etching for an indium phosphide based technology.
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