Two-Dimensional Ferroelectric Photonic Crystals: Optics and Band Structure

In this report we present an investigation of the optical properties and band structure calculations for the photonic structures based on the functional materials- ferroelectrics. A theoretical approach to the optical properties of the 2D and 3D photonic crystals which yields further insight in the phenomenon of the reflection from different families of lattice planes in relation to the presence of photonic gaps or photonic bands. We calculate the photonic bands and optical properties of LiNbO3 based photonic crystals. Calculations of reflection and transmission spectra show the features correspond to the onset of diffraction, as well as to additional reflectance structures at large values of the angle of incidence.Comment: 10 pages, 4 figures, 1 table, This paper were presented at 21 st International Symposium on Applications of Ferroelectrics (ISAF ECAPD PFM 2012 Averio, Portugal) and accepted for publication in Ferroelectrics (2013

Nanostructured Silicon Sensors

Nanostructure porous silicon layers with systematically varied pore size of 8–70 nm were fabricated onto the p-type c-Si wafers using electrochemical anodizing method from HF + ethanol and HF + ethanol + CdCl2 solutions (hereafter PS and PSCD, respectively). Gas and photo sensors based on c-Si/PS (or PSCD)/CdS and c-Si/PS/Cd0.4Zn0.6O heterojunctions were synthesized by depositing CdS and Cd0.4Zn0.6O films onto the c-Si/PS (or PSCD) substrates by electrochemical deposition (ED hereafter). The morphology of the PS and PSCD layers, CdS, and Cd0.4Zn0.6O films was studied using scanning electron microscopy (SEM). Gas- and photosensitivity properties of heterojunctions were studied as a function of pore size. The optimal pore size is determined, which provides the maximum gas- and photosensitivity of heterojunctions in this study. It was established that the heterojunctions based on PSCD possess higher gas- and photosensitivity than heterojunctions based on PS

AdS/CFT correspondence via R-current correlation functions revisited

Motivated by realizing open/closed string duality in the work by Gopakumar [Phys. Rev. D70:025009,2004], we study two and three-point correlation functions of R-current vector fields in N=4 super Yang-Mills theory. These correlation functions in free field limit can be derived from the worldline formalism and written as heat kernel integrals in the position space. We show that reparametrizing these integrals converts them to the expected AdS supergravity results which are known in terms of bulk to boundary propagator. We expect that this reparametrization corresponds to transforming open string moduli parameterization to the closed string ones.Comment: 23 pages, v2: calculations clarified, references added, v3: sections re-arranged with more explanations, 4 figures and an appendix adde

Organic semiconductor-based photonic crystals for solar cell arrays: band gap and optical properties

Cataloged from PDF version of article.Photonic crystals (PCs) hold great potential for designing new optical devices because of the possibility of the manipulation of light with PCs. There has been an increase in research on tuning the optical properties of PCs to design devices. We design organic semiconductor-based PC structures and calculate optical properties using the plane wave expansion method and finite-difference time-domain method in an air background for a hexagonal lattice. We showed the possibility of the solar cell arrays for a 2D PC cavity on an organic semiconductor base infiltrated with a nematic liquid crystal. E7 type has been used as a nematic liquid crystal and 4,4-Bis[4-(diphenylamino) styryl]biphenyl as an organic semiconductor material

Energy States of Colored Particle in a Chromomagnetic Field

The unitary transformation, which diagonalizes squared Dirac equation in a constant chromomagnetic field is found. Applying this transformation, we find the eigenfunctions of diagonalized Hamiltonian, that describe the states with definite value of energy and call them energy states. It is pointed out that, the energy states are determined by the color interaction term of the particle with the background chromofield and this term is responsible for the splitting of the energy spectrum. We construct supercharge operators for the diagonal Hamiltonian, that ensure the superpartner property of the energy states.Comment: 25 pages, some calculation details have been removed, typos correcte

Modeling and simulation of the ferroelectric based micro gyroscope: FEM analysis

Cataloged from PDF version of article.This paper presents the design and modeling of micro-electromechanical systems (MEMS) on the ternary ferroelectric compounds (PZT) based by using finite element model (FEM) simulation. The conceptual framework establishes five steps to perform the critical analysis: design a novel structure, define the failure mechanisms under the given conditions, analyze different vibrations, analyze the operation principle, and detect resonance modes. In addition, MEMS failure modes were analyzed under different scenarios and the obtained results discussed

Optical properties and electronic band structure of topological insulators (on A5 2B6 3 compound based)

Cataloged from PDF version of article.We have performed a first principles study of structural, electronic, and optical properties of rhombohedral Sb2Te3 and Bi 2Te3 compounds using the density functional theory within the local density approximation. The lattice parameters, bulk modulus, and its pressure derivatives of these compounds have been obtained. The linear photon-energy dependent dielectric functions and some optical properties such as the energy-loss function, the effective number of valance electrons and the effective optical dielectric constant are calculated and presented in the study. © 2013 Copyright Taylor and Francis Group, LLC