Francisco Sircilli - Academia.edu (original) (raw)

Papers by Francisco Sircilli

 Very important issues concerning numerical simulation of infrared scenarios in military applica... more  Very important issues concerning numerical simulation of infrared scenarios in military applications are the radiometric emission properties of aircraft plumes as well as the engine tail pipes. In this paper, a detailed description of the experimental set-up and some results of the infrared characterization of a micro turbine engine at ground level (having altitude of ~1500 m AMSL) are presented. The main instruments used were a medium wave infrared camera and a spectroradiometer. The radiometric properties were evaluated in three situations: firstly, by varying the aspect angle between the camera’s field of view and the turbine’s longitudinal axis, while maintaining a fixed engine velocity of rotation; secondly by varying this velocity for fixed aspect angle and, finally, for a small spectroradiometer field of view when observing three different points along the plume. The engine’s infrared numerical model, based on its observed infrared radiometric properties, is intended to be ...

IEEE Transactions on Magnetics, 2001

This work presents the design of a hybrid undulator for an amplifier free-electron laser (FEL) th... more This work presents the design of a hybrid undulator for an amplifier free-electron laser (FEL) that is composed of a periodic magnetic structure of permanent magnets and soft ferromagnetic poles. The basic parameters of the project were obtained by means of computational calculations with a two-dimensional code for the magnetic field and numerical integration of the small-signal gain of the

We propose three designs of microstructured optical fibers for chromatic dispersion compensation.... more We propose three designs of microstructured optical fibers for chromatic dispersion compensation. Dispersion of -3500, -25000, and -135000 ps/nm/km were obtained with FWHM of ~30 nm, ~6 nm, and ~2 nm, respectively.

AIP Conference Proceedings, 2008

We report a study of using photonic crystal fibers (PCFs) for high pressure applications. An opto... more We report a study of using photonic crystal fibers (PCFs) for high pressure applications. An opto-mechanical analysis was realized in regular PCFs and suspended-core microstructured optical fibers for different fiber geometrical parameters. It was found that the pressure sensitivity is highly dependent on the fiber structure. It was also experimentally shown that even small core PCFs with high air filling fraction can deal with pressures as high as 500 bar (7350 psi) without any noticeable problem.

AIP Conference Proceedings, 2008

In this paper we report the numerical evaluation of the opto-mechanical response of a microstruct... more In this paper we report the numerical evaluation of the opto-mechanical response of a microstructured optical fiber design when submitted to hydrostatic pressure. The fiber was built in silica and is composed of two large holes surrounding a wide thin flat region (suspended-slab-core) that is able to support optical propagating modes. A full-vector finite element program was used to the

IEEE Transactions on Aerospace and Electronic Systems, 2015

Resumo -Características quase-estáticas de guias de ondas coplanares (CPW) elípticos coexcêntrico... more Resumo -Características quase-estáticas de guias de ondas coplanares (CPW) elípticos coexcêntricos são analisadas utilizando o Método dos Elementos Finitos. A permissividade efetiva e a impedância característica de um guia de ondas com eletrodos na face externa do substrato são determinadas em função da excentricidade das elipses e da largura do eletrodo "quente". O efeito da espessura dos eletrodos na determinação desses parâmetros também é apresentado.

As características de dispersão dos modos Ex e Ey em guias ópticos planares construídos por proce... more As características de dispersão dos modos Ex e Ey em guias ópticos planares construídos por processo de difusão de Ti em substrato dielétrico de LiNbO3, foram determinadas em função de alguns parâmetros de fabricação: espessura do filme de Ti, tempo e temperatura de difusão. No estudo do problema de domínio aberto, foi utilizado o método dos elementos finitos (formulação unidimensional) associado à técnica de transformação espacial, que permite um eficiente truncamento de domínio.

Apesar das equações de Maxwell descreverem completamente os fenômenos eletromagnéticos macroscópi... more Apesar das equações de Maxwell descreverem completamente os fenômenos eletromagnéticos macroscópicos, sua solução analítica é impraticável em dispositivos com geometrias complexas. Os métodos numéricos são uma alternativa para a obtenção de soluções aproximadas. O Método dos Elementos Finitos (MEF) tem se consagrado, nestas últimas duas décadas, como uma das mais poderosas ferramentas utilizadas na análise e projeto de dispositivos eletromagnéticos e sistemas elétricos. O MEF destaca-se pela capacidade de tratar problemas com geometrias complexas, meios materiais com anisotropia e não homogeneidades arbitrárias. Pode-se, ainda, incluir perdas e considerar meios não lineares. A aplicação do MEF pode ser dividida em três etapas, chamadas pré-processamento, processamento e pós-processamento. O pré-processamento engloba o desenho da geometria do objeto (modelo geométrico), a geração da malha (subdivisão do domínio em elementos finitos), a imposição das propriedades físicas dos materiais...

Proceedings of the 2001 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference. (Cat. No.01TH8568), 2001

This work presents an approach for the analysis of guided and quasi-guided modes in planar electr... more This work presents an approach for the analysis of guided and quasi-guided modes in planar electron waveguides with arbitrarily shaped potential and arbitrary effective mass profiles. The Finite Element Method (FEM) allied to a Perfectly Matched Layer-Like (PML-Like) spatial mapping is used for the phase constant and the mode confinement computations. The adopted spatial transformation maps an infinitely large region, surrounding an open waveguide, to a layer of finite thickness.

Proceedings of the 2001 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference. (Cat. No.01TH8568), 2001

CLEO/Pacific Rim 2003. The 5th Pacific Rim Conference on Lasers and Electro-Optics (IEEE Cat. No.03TH8671), 2003

A finite-element-based vectorial optical mode solver, furnished with Bayliss-Gunzburger-Turkel-li... more A finite-element-based vectorial optical mode solver, furnished with Bayliss-Gunzburger-Turkel-like transparent boundary conditions, is used to rigorously analyze photonic crystal fibers (PCFs). Both the real and imaginary part of the modal indices can be computed in a relatively small computational domain. The leakage loss, the dispersion properties, the vectorial character, as well as the degeneracy of modes of the fibers can be studied through the finite element results. Results for PCFs with either circular or non-circular microstructured holes, solidor air-core will be presented, including the air-core air-silica Bragg fiber. Using the mode solver, the single-modeness of a commercial endlessly single-mode PCF was also investigated.

2008 Conference on Lasers and Electro-Optics, 2008

We propose three designs of microstructured optical fibers for chromatic dispersion compensation.... more We propose three designs of microstructured optical fibers for chromatic dispersion compensation. Dispersion of − 3500, − 25000, and − 135000 ps/nm/km were obtained with FWHM of ∼30 nm, ∼6 nm, and ∼2 nm, respectively.

EUROCON 2007 - The International Conference on "Computer as a Tool", 2007

In this paper the propagation properties of microstructured optical fiber with 12-fold quasicryst... more In this paper the propagation properties of microstructured optical fiber with 12-fold quasicrystal lattice of air-holes in a silica matrix have been studied for the first time. Lattices with different hole diameters were considered and curves for the effective index, dispersion and effective area were calculated by a finite element code. The dispersion properties of quasicrystal fibers were compared to that of microstructured fibers with triangular lattice of holes. For dispersion compensation purpose it is proposed a modified 12-fold microstructured quasicrystal fiber with a concentric dual-core structure. With the dual-core design high negative dispersion values ∼ ∼ ∼ ∼ − − − − 40,000 ps/(nm km) could be reached for the wavelength around 1550 nm.

Optics Letters, 2007

A microstructured optical fiber with a single design parameter is proposed and demonstrated. In s... more A microstructured optical fiber with a single design parameter is proposed and demonstrated. In such a structure three thin, long glass webs join in the fiber center, forming its core. By changing the web thickness it is possible to tune the zero-dispersion wavelength from ϳ0.7 to Ͼ 2.0 m while keeping a tiny core area and single-mode guidance. Supercontinuum generation is shown in a silica fiber with a web thickness of 850 nm. The small core area and the massive hole area also make the structure very attractive for the sensing and study of fluids.

Microwave and Optical Technology Letters, 2008

In this article, we analyze the birefringence of photonic crystal fibers with squeezed rectangula... more In this article, we analyze the birefringence of photonic crystal fibers with squeezed rectangular lattices by using finite element method. When the original photonic crystal fiber is squeezed, the lattice is compressed, and the holes become elliptical. This operation leads to birefringences as high as 7.5 ϫ 10 Ϫ3 at 1550 nm. However, confinement losses and dispersion are also changed after this operation is performed, needing to be reassessed. We estimate the changes in dispersion and confinement losses after this operation is performed.

Journal of Lightwave Technology, 2002

This work analyzes the effect of the proton-concentration-to-refractive-index relation on the com... more This work analyzes the effect of the proton-concentration-to-refractive-index relation on the computation of waveguiding properties of well-annealed proton-exchanged channel waveguides fabricated in a LiNbO 3 substrate. Several of such relations are presented in literature. The application of these different relations in the numerical analysis results in a very different propagation behavior for the waveguide. For comparison purposes, an empirical relation that fits the published refractive-index-versus-proton-concentration experimental data for the crystalline phase is also used. Index Terms-Lithium materials/devices, optical propagation in anisotropic media, optical propagation in nonhomogeneous media, optical strip waveguides.

 Very important issues concerning numerical simulation of infrared scenarios in military applica... more  Very important issues concerning numerical simulation of infrared scenarios in military applications are the radiometric emission properties of aircraft plumes as well as the engine tail pipes. In this paper, a detailed description of the experimental set-up and some results of the infrared characterization of a micro turbine engine at ground level (having altitude of ~1500 m AMSL) are presented. The main instruments used were a medium wave infrared camera and a spectroradiometer. The radiometric properties were evaluated in three situations: firstly, by varying the aspect angle between the camera’s field of view and the turbine’s longitudinal axis, while maintaining a fixed engine velocity of rotation; secondly by varying this velocity for fixed aspect angle and, finally, for a small spectroradiometer field of view when observing three different points along the plume. The engine’s infrared numerical model, based on its observed infrared radiometric properties, is intended to be ...

IEEE Transactions on Magnetics, 2001

This work presents the design of a hybrid undulator for an amplifier free-electron laser (FEL) th... more This work presents the design of a hybrid undulator for an amplifier free-electron laser (FEL) that is composed of a periodic magnetic structure of permanent magnets and soft ferromagnetic poles. The basic parameters of the project were obtained by means of computational calculations with a two-dimensional code for the magnetic field and numerical integration of the small-signal gain of the

We propose three designs of microstructured optical fibers for chromatic dispersion compensation.... more We propose three designs of microstructured optical fibers for chromatic dispersion compensation. Dispersion of -3500, -25000, and -135000 ps/nm/km were obtained with FWHM of ~30 nm, ~6 nm, and ~2 nm, respectively.

AIP Conference Proceedings, 2008

We report a study of using photonic crystal fibers (PCFs) for high pressure applications. An opto... more We report a study of using photonic crystal fibers (PCFs) for high pressure applications. An opto-mechanical analysis was realized in regular PCFs and suspended-core microstructured optical fibers for different fiber geometrical parameters. It was found that the pressure sensitivity is highly dependent on the fiber structure. It was also experimentally shown that even small core PCFs with high air filling fraction can deal with pressures as high as 500 bar (7350 psi) without any noticeable problem.

AIP Conference Proceedings, 2008

In this paper we report the numerical evaluation of the opto-mechanical response of a microstruct... more In this paper we report the numerical evaluation of the opto-mechanical response of a microstructured optical fiber design when submitted to hydrostatic pressure. The fiber was built in silica and is composed of two large holes surrounding a wide thin flat region (suspended-slab-core) that is able to support optical propagating modes. A full-vector finite element program was used to the

IEEE Transactions on Aerospace and Electronic Systems, 2015

Resumo -Características quase-estáticas de guias de ondas coplanares (CPW) elípticos coexcêntrico... more Resumo -Características quase-estáticas de guias de ondas coplanares (CPW) elípticos coexcêntricos são analisadas utilizando o Método dos Elementos Finitos. A permissividade efetiva e a impedância característica de um guia de ondas com eletrodos na face externa do substrato são determinadas em função da excentricidade das elipses e da largura do eletrodo "quente". O efeito da espessura dos eletrodos na determinação desses parâmetros também é apresentado.

As características de dispersão dos modos Ex e Ey em guias ópticos planares construídos por proce... more As características de dispersão dos modos Ex e Ey em guias ópticos planares construídos por processo de difusão de Ti em substrato dielétrico de LiNbO3, foram determinadas em função de alguns parâmetros de fabricação: espessura do filme de Ti, tempo e temperatura de difusão. No estudo do problema de domínio aberto, foi utilizado o método dos elementos finitos (formulação unidimensional) associado à técnica de transformação espacial, que permite um eficiente truncamento de domínio.

Apesar das equações de Maxwell descreverem completamente os fenômenos eletromagnéticos macroscópi... more Apesar das equações de Maxwell descreverem completamente os fenômenos eletromagnéticos macroscópicos, sua solução analítica é impraticável em dispositivos com geometrias complexas. Os métodos numéricos são uma alternativa para a obtenção de soluções aproximadas. O Método dos Elementos Finitos (MEF) tem se consagrado, nestas últimas duas décadas, como uma das mais poderosas ferramentas utilizadas na análise e projeto de dispositivos eletromagnéticos e sistemas elétricos. O MEF destaca-se pela capacidade de tratar problemas com geometrias complexas, meios materiais com anisotropia e não homogeneidades arbitrárias. Pode-se, ainda, incluir perdas e considerar meios não lineares. A aplicação do MEF pode ser dividida em três etapas, chamadas pré-processamento, processamento e pós-processamento. O pré-processamento engloba o desenho da geometria do objeto (modelo geométrico), a geração da malha (subdivisão do domínio em elementos finitos), a imposição das propriedades físicas dos materiais...

Proceedings of the 2001 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference. (Cat. No.01TH8568), 2001

This work presents an approach for the analysis of guided and quasi-guided modes in planar electr... more This work presents an approach for the analysis of guided and quasi-guided modes in planar electron waveguides with arbitrarily shaped potential and arbitrary effective mass profiles. The Finite Element Method (FEM) allied to a Perfectly Matched Layer-Like (PML-Like) spatial mapping is used for the phase constant and the mode confinement computations. The adopted spatial transformation maps an infinitely large region, surrounding an open waveguide, to a layer of finite thickness.

Proceedings of the 2001 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference. (Cat. No.01TH8568), 2001

CLEO/Pacific Rim 2003. The 5th Pacific Rim Conference on Lasers and Electro-Optics (IEEE Cat. No.03TH8671), 2003

A finite-element-based vectorial optical mode solver, furnished with Bayliss-Gunzburger-Turkel-li... more A finite-element-based vectorial optical mode solver, furnished with Bayliss-Gunzburger-Turkel-like transparent boundary conditions, is used to rigorously analyze photonic crystal fibers (PCFs). Both the real and imaginary part of the modal indices can be computed in a relatively small computational domain. The leakage loss, the dispersion properties, the vectorial character, as well as the degeneracy of modes of the fibers can be studied through the finite element results. Results for PCFs with either circular or non-circular microstructured holes, solidor air-core will be presented, including the air-core air-silica Bragg fiber. Using the mode solver, the single-modeness of a commercial endlessly single-mode PCF was also investigated.

2008 Conference on Lasers and Electro-Optics, 2008

We propose three designs of microstructured optical fibers for chromatic dispersion compensation.... more We propose three designs of microstructured optical fibers for chromatic dispersion compensation. Dispersion of − 3500, − 25000, and − 135000 ps/nm/km were obtained with FWHM of ∼30 nm, ∼6 nm, and ∼2 nm, respectively.

EUROCON 2007 - The International Conference on "Computer as a Tool", 2007

In this paper the propagation properties of microstructured optical fiber with 12-fold quasicryst... more In this paper the propagation properties of microstructured optical fiber with 12-fold quasicrystal lattice of air-holes in a silica matrix have been studied for the first time. Lattices with different hole diameters were considered and curves for the effective index, dispersion and effective area were calculated by a finite element code. The dispersion properties of quasicrystal fibers were compared to that of microstructured fibers with triangular lattice of holes. For dispersion compensation purpose it is proposed a modified 12-fold microstructured quasicrystal fiber with a concentric dual-core structure. With the dual-core design high negative dispersion values ∼ ∼ ∼ ∼ − − − − 40,000 ps/(nm km) could be reached for the wavelength around 1550 nm.

Optics Letters, 2007

A microstructured optical fiber with a single design parameter is proposed and demonstrated. In s... more A microstructured optical fiber with a single design parameter is proposed and demonstrated. In such a structure three thin, long glass webs join in the fiber center, forming its core. By changing the web thickness it is possible to tune the zero-dispersion wavelength from ϳ0.7 to Ͼ 2.0 m while keeping a tiny core area and single-mode guidance. Supercontinuum generation is shown in a silica fiber with a web thickness of 850 nm. The small core area and the massive hole area also make the structure very attractive for the sensing and study of fluids.

Microwave and Optical Technology Letters, 2008

In this article, we analyze the birefringence of photonic crystal fibers with squeezed rectangula... more In this article, we analyze the birefringence of photonic crystal fibers with squeezed rectangular lattices by using finite element method. When the original photonic crystal fiber is squeezed, the lattice is compressed, and the holes become elliptical. This operation leads to birefringences as high as 7.5 ϫ 10 Ϫ3 at 1550 nm. However, confinement losses and dispersion are also changed after this operation is performed, needing to be reassessed. We estimate the changes in dispersion and confinement losses after this operation is performed.

Journal of Lightwave Technology, 2002

This work analyzes the effect of the proton-concentration-to-refractive-index relation on the com... more This work analyzes the effect of the proton-concentration-to-refractive-index relation on the computation of waveguiding properties of well-annealed proton-exchanged channel waveguides fabricated in a LiNbO 3 substrate. Several of such relations are presented in literature. The application of these different relations in the numerical analysis results in a very different propagation behavior for the waveguide. For comparison purposes, an empirical relation that fits the published refractive-index-versus-proton-concentration experimental data for the crystalline phase is also used. Index Terms-Lithium materials/devices, optical propagation in anisotropic media, optical propagation in nonhomogeneous media, optical strip waveguides.