Navegando por Autor "Mauriz, P. W."

Agora exibindo 1 - 5 de 5

Optical filters based in quasiperiodic photonic crystal
(Elsevier, 2009) Vasconcelos, Manoel Silva de; Mauriz, P. W.; Albuquerque, Eudenilson Lins de
In this work we investigate theoretically the behavior of a light beam incident on a wð2Þ nonlinear quasiperiodic photonic crystal (or quasiperiodic S˘olc filter), in which each building block containing a pair LiNbO3 layers with antiparallel poled domains, arranged in a quasiperiodical fashion which follows the Pell, Fibonacci, Thue–Morse, and double-period substitutional sequences. The transmittances at filtering wavelengths can be modulated from 0 to 1 by applying an external voltage but the filtering wavelengths are unchanged. We show that the filtering wavelengths tuned by varying voltage around 0.9 kV, indicate that quasiperiodic S˘olc filter based in Pell and Thue–Morse sequences are so efficient as the Fibonacci S˘olc filter, while the double-period sequence have a low efficiency
Optical gain spectra of unstrained graded GaAs/AlxGa1−xAs quantum well laser
(Elsevier, 2012) Albuquerque, Eudenilson Lins de; Fulco, Umberto Laino; Vasconcelos, Manoel Silva de; Mauriz, P. W.
We have calculated the optical gain spectra in unstrained graded GaAs/AlxGa1 − xAs single quantum well lasers as a function of the energy of the radiation, the quantum well width and the interface thickness. The optical gain spectra were calculated using the density matrix approach (Luttinger–Kohn method), considering the parabolic band model (conduction band), all subband mixing between the heavy and light holes (valence band), and the transversal electrical light polarization. Our results show that the optical peak gain is sensitive to the width and the graded profile of the interfaces, and is blue-shifted as a function of the interface width
Optical transmission spectra in symmetrical Fibonacci photonic multilayers
(Elsevier, 2009) Mauriz, P. W.; Vasconcelos, Manoel Silva de; Albuquerque, Eudenilson Lins de
We study the transmission properties of light through the symmetric Fibonacci photonic multilayers, i.e, a binary one-dimensional quasiperiodic structure, made up of both positive (SiO2) and negative refractive index materials with a mirror symmetry. These spectra are calculated by using a theoretical model based on the transfer matrix approach for normal incidence geometry, in which many perfect transmission peaks (the transmission coefficients are equal to the unity) are numerically obtained. Besides, the transmission coefficient exhibits a six-cycle self-similar behavior with respect to the generation number of the Fibonacci sequence
Oscillatory behavior of the specific heat at low temperature in quasiperiodic structures
(Elsevier, 2004-12-15) Bezerra, Claudionor Gomes; Albuquerque, Eudenilson Lins de; Mauriz, P. W.; Vasconcelos, Manoel Silva de
We investigate the thermodynamical properties of plasmon–polaritons that propagate in multiple semiconductor layers arranged in a quasi-periodical fashion of Fibonacci and Thue–Morse types. We have chosen these two types of quasi-periodic structures for the following reasons: (i) both were realized experimentally, so they are not mere academic examples of a quasi-crystal; (ii) it is believed that the Thue–Morse chain is more disordered than the Fibonacci one, i.e., it has a degree of aperiodicity intermediate between the Fibonacci chain and the random systems. More precisely, the Fourier amplitude spectrum of the Thue–Morse sequence is singular continuous, while for the Fibonacci case we found δ-function peaks not arranged periodically. Both analytical and numerical studies on the temperature dependence of the excitation's specific heat associated with the generation number n=1,2,3,… for their multiscale fractal energy spectra are presented. We show that when T tends to zero, the specific heat displays oscillations and when T tends to infinity, the specific heat goes to zero as T−2, because the energy spectrum considered is bounded
Thermal radiation in quasiperiodic photonic crystals
(Elsevier, 2009) Mauriz, P. W.; Vasconcelos, Manoel Silva de; Medeiros, F. F. de; Albuquerque, Eudenilson Lins de
In this work we investigated the thermal power spectrum of the electromagnetic radiation through onedimensional stacks of alternating negative and positive refractive index layers, arranged as truncated quasiperiodic photonic structures obeying the Fibonacci (FB), Thue–Morse (TM), and double-period (DP) sequences. The thermal radiation power spectra are determined by means of a theoretical model based on a transfer matrix formalism for both normal and oblique incidence geometries, together with Kirchoff’s second law. We studied the radiation spectra by considering the case where both refractive indices of layers A and B are assumed to be a constant, as well as a more realistic case which takes into account the frequency-dependent electric permittivity and magnetic permeability m to characterize the negative refractive index n in layer B

SIGAA

Navegando por Autor "Mauriz, P. W."