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Showing 6 results for Materials

Y. Hatefi, K. Anbaz, A. Moghimi, B. Maddah,
Volume 4, Issue 1 (1-2010)
Abstract

Europium doped transparent lead fluorophosphate glass ceramics successfully were prepared with heat treatment of precourse glasses at temperature above glass transition (Tg). X-ray diffraction (XRD) experiment evidenced the formation of PbF2 nanocrystals in glassy matrix. The emission spectra investigation indicate that considerable amount of Eu3+ ions were trapped in crystalline phase, and therefore the efficient frequency-conversion was observed in glass ceramics samples. The investigated glass ceramics systems are potentially applicable as up and down frequency-conversion photonics materials.
Dr. Majid Ghanaat Shoar, Dr. Somayeh Rafiee Dastjerdi, Dr. Kaveh Delfanazaric,
Volume 8, Issue 1 (1-2014)
Abstract

We study the focusing properties of a two dimensional complex square-lattice photonic crystal (PC) comprising air holes immersed in Ge medium. The finite difference time domain (FDTD) method is utilized to calculate the dispersion band diagram and to simulate the image formation incorporating the perfectly matched layer (PML) boundary condition. In contrast to the common square PCs with the same air filling factor, the frequency corresponding to the effective negative refraction occurs in the second photonic band and the spatial image resolution is improved.
Mr Mohammadreza Forouzeshfard, Prof. Tomas Tyc, Dr. Mahmood Hosseini Farzad,
Volume 8, Issue 2 (7-2014)
Abstract

Based on transformation optics‎, ‎we propose an illusion device that can make‎ ‎objects look much smaller and different than they actually are‎. ‎In particular‎, ‎the device has a capability to hide a large object (like an elephant) into a‎ ‎small one (like a matchbox)‎. ‎Compared to previous proposals for illusion‎ ‎devices‎, ‎there is no requirement for negative refractive index or for speed of‎ ‎light going to infinity as in Euclidean invisible cloaks‎. ‎We demonstrate the‎ ‎functionality of the device by full wave simulations‎.
Dr Vahid Ahmadi, Mr Saeed Pahlavan,
Volume 10, Issue 1 (4-2016)
Abstract

Photonic crystal design procedure for negative refraction has so far been based on trial and error. In this paper, for the first time, a novel and systematic design procedure based on physical and mathematical properties of photonic crystals is proposed to design crystal equi-frequency contours (EFCs) to produce negative refraction. The EFC design is performed by the help of rectangular stair-case (RSC) photonic crystals. The RSC crystal is then converted to more common structures like pillar crystals by matching Fourier coefficients of periodic electric permittivity. Methods to design common crystals which have approximately equal Fourier components to the RSC crystal are also discussed. The proposed procedure can be used to design metamaterials without the difficulties of large trial and error. The devised procedure can also be applied in designing other structures involving photonic crystals.


Marjan Jafari, Fatemeh Moradi,
Volume 12, Issue 2 (12-2018)
Abstract

A bi-isotropic magneto-electric metamaterials is modeled by two independent reservoirs. The reservoirs contain a continuum of three dimensional harmonic oscillators, which describe polarizability and magnetizability of the medium. The paper aimed to investigate the effect of electromagnetic field on bi-isotropic. Starting with a total Lagrangian and using Euler-Lagrange equation, researcher could obtain a quantum Langevin type dissipative equation for electromagnetic field. Generating functional of the system is obtained by the path integral method and based on the perturbative approach. By generating functional, a series expansion in terms of susceptibility function of the bi-isotropic metamaterials is obtained for correlation function or two-point Green’s function. In special case, the close relationship between statistical mechanics and quantum field theory,which was reflected in the path integral methods, could obtain free energy of electromagnetic field for isotropic metamaterial using two-point Green’s function. As an example, the Casimir force of two polarizable metamaterial spheres by Lorentz susceptibilities was studied. Furthermore, Casimir force of two polarizable-magnetizable metamaterials was calculated.


Bobby Barua,
Volume 14, Issue 2 (12-2020)
Abstract

Optical resonators where light will circulate in two opposite directions independently. Usually, the two distinct topologies of optical resonators are Linear and Ring. Two end mirrors with perpendicular light incidence have linear resonators (standing-wave resonators). In the other hand, there are no end mirrors in ring resonators; none of the resonator mirrors reflects light back into itself. Given its versatility and cost-effectiveness, it is beneficial to provide a low index ring resonator. Compared with existing high index technologies it can provide an attractive solution. The refractive index difference plays a key role in evaluating the properties of an optical dielectric waveguide, and a higher index contrast allows for shifting to greater integration scales and accessibility to new technologies and interfaces. However high contrast waveguides are harder to realize and more important, that their use does not raise any severe impediments. The intent of this article is to evaluate the impact of the waveguide features with regard to the correlation of the index and to investigate the complexities. This paper evaluates the influence of the index contrast on dielectric waveguide characteristics such as single mode system, losses, technical constraints, and available materials. Evaluation is developed by utilizing Rsoft CAD, known as BeamProp software, for ring resonators (single, double or triple optical loop). The main objective of this contribution is to achieve maximum flexibility and more productivity from the proposed design. This paper is an analogy for the design of optical waveguides, so that we can achieve flexibility by lowering the silicon index.

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