Banca de DEFESA: EDI ROZEMBERGH BRASILEIRO DA SILVA BRANDÃO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : EDI ROZEMBERGH BRASILEIRO DA SILVA BRANDÃO
DATA : 20/10/2016
HORA: 15:00
LOCAL: Auditório do DFTE
TÍTULO:

ESPECTRO DE TRANSMISSÃO ÓPTICAS E POLARITONS EM QUASI-CRISTAIS DE OCTONACCI

PALAVRAS-CHAVES:

Quasi-cristals, octonacci, photonic crystals, photonic band gap, metamaterials, polariton, plasmon

PÁGINAS: 132
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
SUBÁREA: Física da Matéria Condensada
RESUMO:

Abstract:
In this work, we present a theoretical study of the propagation of electromagnetic waves in multilayer structures termed Photonic Crystals. Within this scope, this work has three strands. In the first part, we study theoretically the transmission spectra in one-dimensional photonic quasi-crystals, made up of SiO2 (A) and TiO2 (B), materials, organized following the Octonacci sequence, where the nth-stage of the multilayer Sn is given by the rule Sn=Sn-1Sn-2Sn-1, for n ≥ 3 and with S1=A e S2=B. The expression for transmittance was obtained by employing a theoretical calculation based on the transfer-matrix method. For normally incident waves, we observe that, for a same generation, the transmission spectra for transverse electric (TE) and transverse magnetic (TM) waves are equal, at least qualitatively, and they present a scaling property where a self-similar behavior is obtained, as an evidence that these spectra are fractals. The spectra show regions where the omnidirectional band gaps emerges for specific generations of Octonacci photonic structure, except to TM waves. For TE waves, we note that all of them have almost the same width, for different generations. We also report the localization of modes as a consequence of the quasi-periodicity of the heterostructure.

In the second part, we investigate the optical transmission spectra for s and p-polarized (TE) waves in one-dimensional photonic quasi-crystals on a quasi-periodic multilayer structure made up by alternate layers of SiO2 and metamaterials, organized by following the Octonacci sequence. Maxwell's equations and the transfer-matrix technique are used to derive the transmission spectra for the propagation of normaly and obliquely incident electromagnetic fields. We assume Drude-Lorentz-type dispersive response for the dielectric permittivity and magnetic permeability of the metamaterials. For normally incident waves, we observe that the spectra does not have self-similar behavior or mirror symmetry and it also features the absence of optical band gap. We also show the appearance of the complete band gaps and pseudo reflectors Bragg (or Bragg mirrors).

In the third and final part, we studied the propagation of plasmons polariton in systems formed by periodic multilayer and quasi-periodic organized in accordance to the Octonacci sequence from the behavior description of their modes of volume and surface in their individual constituents. Through analytical and computational numerical calculation, initially we get the frequency spectra of plasmon polariton these superstructures. Subsequently, we investigated the quasi-periodicity changes its band structure in relation to the periodic case, inducing their spectra to a self-similar way, characterizing its fractality/multifractality.

MEMBROS DA BANCA:
Presidente - 1354851 - MANOEL SILVA DE VASCONCELOS
Interno - 1519258 - DORY HELIO AIRES DE LIMA ANSELMO
Interno - 345638 - EUDENILSON LINS DE ALBUQUERQUE
Externo à Instituição - CARLOS ALEXANDRE AMARAL ARAUJO - IFMA
Externo à Instituição - PAULO WILSON MAURIZ - IFMA