Optical Propagation
Mostrando 1-12 de 86 artigos, teses e dissertações.
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1. MGF Methods for Fixed and Gain Saturated Optically Preamplified FSO Links Impaired by Misalignments and Atmospheric Turbulence
Abstract The Gaussian approximation is commonly used to evaluate the performance of free space optical communication systems. However, other performance evaluation methods such as the saddle point approximation, Chernoff bound and the modified Chernoff bound have also been used. This paper investigates the performance of fixed and gain saturated optically pr
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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2. High-Speed Pulse Sequences through Semiconductor Optical Nonlinear Amplification and Buried Fiber Propagation
Abstract Microwave pulse bursts were obtained through optical domain intensity modulated microwave carriers, sliced by cascaded modulator technique, followed by non-linear semiconductor optical amplifier (SOA) pre-chirp. After 3 to 18 km of buried fiber propagation and photo detection, the microwave signals presented increased extinction ratio, up to 36 GHz,
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2020-09
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3. Optical Fiber Coupler Analysis Using Daubechies Wavelets
Abstract This article presents the theoretical analysis of a signal coupling between a proposed Photonic Crystal Fiber (PCF) and a Conventional Fiber with Step Index (CFSI) system. In this analysis, the Finite Element Method (FEM) and Beam Propagation Method (BPM) are applied together with Daubechies wavelets as basis function and described in the mathematic
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2020-09
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4. Remineralizing Potential of Nano-Silver-Fluoride for Tooth Enamel: An Optical Coherence Tomography Analysis
Abstract Objective: To evaluate the use of nanosilver fluoride in the enamel remineralization process through optical coherence tomography. Material and Methods: All samples were submitted to demineralization process by pH cycling during 14 days and randomly distributed into three groups (n = 11): Nanosilver Fluoride (NSF), Sodium fluoride (NaF), and negat
Pesqui. Bras. Odontopediatria Clín. Integr.. Publicado em: 10/10/2019
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5. Effect of Ca Content on Properties of Extruded Mg-3Zn-0.5Sr-xCa Alloys for Medical Applications
Mg-3Zn-0.5Sr-xCa(wt.%) (x=0, 0.2, 0.5) alloys were fabricated by casting and hot extrusion. X-ray diffraction (XRD) and optical microscopy observation showed that the microstructure of Mg-3Zn-0.5Sr-xCa alloys was composed of α-Mg matrix and Mg17Sr2 phase precipitated along grain boundaries. The tensile strength of the alloy increased from 255MPa to 305MPa w
Mat. Res.. Publicado em: 30/09/2019
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6. Utilizing Shift-or-Shrink Method to Optimize Multisegment Structures of Bent Optical Waveguides
Abstract The authors utilized a heuristic shift-or-shrink method that is associated with the beam propagation method to design an optimal multisegment bent optical waveguide. By transforming the shape of each segment, the multisegment structure of the bent waveguide can be optimized. In addition to achieving maximal transmission efficiency, only four segment
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 12/09/2019
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7. A Comparative Investigation of the Corrosion Resistance and HIC Suceptibility of API 5L X65 and API 5L X80 Steels
High strength low alloy (HSLA) steels are used for the construction of pipelines for oil and natural gas transportation. For such applications pipelines must exhibit mechanical resistance and resistance to corrosion and hydrogen induced cracking (HIC). API 5L X65 steels are the main materials used for this purpose. However, for economic reasons, the use of s
Mat. Res.. Publicado em: 07/01/2019
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8. Obtención de aceros de baja aleación con diferentes contenidos de Ni y similares microestructuras y propiedades mecánicas
ABSTRACT Low alloy steels are used in many applications in the oil and gas industry. The addition of Ni in these steels improves their low temperature fracture toughness and hardenability, with a low penalty on weldability. However, ISO 15156-2 standard restricts Ni content up to a 1 wt% limit, requiring additional and expensive tests if higher Ni steels are
Matéria (Rio J.). Publicado em: 19/07/2018
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9. All-Optical Logic Gates Devices based on SPP Coupling between Graphene Sheets
Abstract The aim of this work is to propose all-optical logic gates based on surface plasmon polaritons (SPP's) coupling among spatially separated graphene sheets. This model consists of graphene nanoribbons embedded in silica (SiO2) substrate place in a distance such that allow an efficient coupling between the plasmonic modes of the waveguides. It was nume
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2018-06
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10. Directional Coupler Based on a Photonic Quasi-Crystal Fiber with Extended Cores
Abstract In this paper, an optical coupler composed by a photonic quasi-crystal fiber (PQCF) with two cores is proposed. The structure is obtained by immersion of a quasi-periodic arrangement of air holes replicated twelve-fold in a conventional fiber optical constituted of pure silica. The cores are generated from defects caused due to absence of two air ho
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2018-06
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11. EDFA Design and Analysis for WDM Optical Systems Based on Modal Multiplexing
Abstract Modal multiplexing (MDM) is a core technology to allow a capacity increase in modern optical systems. However, in MDM links, the amplified WDM signal suffers not only from lack of spectral gain equalization but also from unequal modal gain. The proper design of the MDM-EDFA is crucial to provide modal gain equalization and to overcome those impairme
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2017-03
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12. Propagation Characteristics of Optical Long Period Fiber Gratings using Graphical Solution Methods
Abstract In this paper, we explicitly show a complete analysis and detailed calculation of propagation characteristics of the effective refractive indices of the core and cladding for a long period grating employing both the Two-Layer and Three-Layer Geometries. The results are achieved employing graphical solution methods and presented in terms of the effec
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2016-06