Os metamateriais acústicos/elásticos são materiais que apresentam características elásticas diferentes dos materiais comuns encontrados na natureza, sendo o índice de refração negativo a principal característica destes novos materiais. A literatura reporta que esta propriedade é atingida para uma faixa muito estreita de frequências, sendo um efeito muito localizado, e, adicionalmente, as estruturas propostas são ideais em extremo, o que dificulta sua aplicação prática em dispositivos acústicos. O objetivo do presente trabalho foi projetar metamateriais acústicos e elásticos tridimensionais com índice de refração negativo numa faixa de frequência mais longa em relação ao reportado na literatura, e utilizando geometrias e materiais que tornem viável sua implementação prática para a fabricação de dispositivos. Com este propósito foi desenvolvido um formalismo da teoria de meio efetivo (TME), no limite de comprimento de onda longa e baixas frações de preenchimento. Com a TME desenvolvida foi estudado o espalhamento de inclusões esféricas simples, revestidas e duplamente revestidas em diferentes matrizes hospedeiras. Os resultados mostraram a existência de bandas ressonantes nos coeficientes da matriz T relacionadas aos modos monopolares, dipolares e quadrupolares. Materiais compósitos constituídos por esferas simples, revestidas ou duplamente revestidas foram analisados utilizando o formalismo TME. Os resultados mostraram que os valores negativos dos parâmetros elásticos nestes materiais estão completamente relacionados aos efeitos ressonantes das inclusões esféricas. Metamateriais elásticos e acústicos foram projetados sobrepondo dois ou mais compósitos diferentes, cada um com diferentes propriedades, de tal forma que o efeito total no metamaterial apresente as características definidas no projeto inicial. O metamaterial elástico foi projetado utilizando a sobreposição de três compósitos de inclusões esféricas diferentes. Este metamaterial apresentou índice de refração negativa na região de 2 kHz, numa faixa de largura igual a 80 Hz. O metamaterial acústico foi projetado sobrepondo dois compósitos de inclusões esféricas diferentes. Este material apresentou índice de refração negativa na região de 7 kHz, numa faixa de 500 Hz. As geometrias e materiais utilizados no projeto destes metamateriais são acessíveis e de fácil manipulação, o que facilitará sua futura fabricação em laboratório. Os resultados obtidos neste trabalho sugerem a possibilidade de fabricar estes metamateriais no laboratório e empregá-los no controle de ondas acústicas, elásticas e sísmicas, assim como também no projeto de um manto de invisibilidade acústica/elástica. / The acoustic/elastic metamaterials are materials that show different elastic features from common materials found in nature and their main characteristics are their negative refractive index. The literature reports that this property is reached for a very narrow range of frequencies, as a very localized phenomenon, and additionally, the proposed structures are extremely ideals, which makes its practical application difficult on acoustic devices. The objective of this work was to design acoustic/elastic three-dimensional Metamaterials with negative refractive index in a wider frequency band than that reported in the literature, and using geometries and materials that make it possible their practical implementation for manufacturing acoustic/elastic devices. With this purpose a formalism of the effective medium theory (EMT) was developed, in the limit of wavelength and low fill fractions. With the developed EMT, the scattering of simple spherical inclusions, coated and doubly coated in different host substrates were studied. The results showed the existence of resonant bands in the coefficients of the T matrix related to monopolar, dipolar and quadrupolar modes. Composite materials consisting of simple, coated or double coated spheres were analyzed using the EMT formalism. The results showed that the negative values of elastic parameters in these materials are completely related to resonant effects of the spheres of inclusion. Elastic and acoustic Metamaterials were designed by overlaying two or more different composites, each with different properties, such that the overall effect on the metamaterial shows the desired features defined in the initial project. The elastic metamaterial was designed by overlapping three different composites of different spherical inclusions. This metamaterial shows negative refractive index in the region of 2 kHz, in a band of width of 80 Hz. The acoustic metamaterial was designed by overlapping two composites of different spherical inclusions. This material shows negative refractive index in the region of 7 kHz, in a band of width of 500 Hz. The geometries and materials used in the design of these Metamaterials are affordable and easy to handle, which will facilitate their future fabrication in the laboratory. The results obtained in this study suggest the possibility to manufacture these metamaterials in the laboratory and use them in the control of acoustic, elastic and seismic waves, as well as in the design of invisible cloak.

Os metamateriais acústicos/elásticos são materiais que apresentam características elásticas diferentes dos materiais comuns encontrados na natureza, sendo o índice de refração negativo a principal característica destes novos materiais. A literatura reporta que esta propriedade é atingida para uma faixa muito estreita de frequências, sendo um efeito muito localizado, e, adicionalmente, as estruturas propostas são ideais em extremo, o que dificulta sua aplicação prática em dispositivos acústicos. O objetivo do presente trabalho foi projetar metamateriais acústicos e elásticos tridimensionais com índice de refração negativo numa faixa de frequência mais longa em relação ao reportado na literatura, e utilizando geometrias e materiais que tornem viável sua implementação prática para a fabricação de dispositivos. Com este propósito foi desenvolvido um formalismo da teoria de meio efetivo (TME), no limite de comprimento de onda longa e baixas frações de preenchimento. Com a TME desenvolvida foi estudado o espalhamento de inclusões esféricas simples, revestidas e duplamente revestidas em diferentes matrizes hospedeiras. Os resultados mostraram a existência de bandas ressonantes nos coeficientes da matriz T relacionadas aos modos monopolares, dipolares e quadrupolares. Materiais compósitos constituídos por esferas simples, revestidas ou duplamente revestidas foram analisados utilizando o formalismo TME. Os resultados mostraram que os valores negativos dos parâmetros elásticos nestes materiais estão completamente relacionados aos efeitos ressonantes das inclusões esféricas. Metamateriais elásticos e acústicos foram projetados sobrepondo dois ou mais compósitos diferentes, cada um com diferentes propriedades, de tal forma que o efeito total no metamaterial apresente as características definidas no projeto inicial. O metamaterial elástico foi projetado utilizando a sobreposição de três compósitos de inclusões esféricas diferentes. Este metamaterial apresentou índice de refração negativa na região de 2 kHz, numa faixa de largura igual a 80 Hz. O metamaterial acústico foi projetado sobrepondo dois compósitos de inclusões esféricas diferentes. Este material apresentou índice de refração negativa na região de 7 kHz, numa faixa de 500 Hz. As geometrias e materiais utilizados no projeto destes metamateriais são acessíveis e de fácil manipulação, o que facilitará sua futura fabricação em laboratório. Os resultados obtidos neste trabalho sugerem a possibilidade de fabricar estes metamateriais no laboratório e empregá-los no controle de ondas acústicas, elásticas e sísmicas, assim como também no projeto de um manto de invisibilidade acústica/elástica. / The acoustic/elastic metamaterials are materials that show different elastic features from common materials found in nature and their main characteristics are their negative refractive index. The literature reports that this property is reached for a very narrow range of frequencies, as a very localized phenomenon, and additionally, the proposed structures are extremely ideals, which makes its practical application difficult on acoustic devices. The objective of this work was to design acoustic/elastic three-dimensional Metamaterials with negative refractive index in a wider frequency band than that reported in the literature, and using geometries and materials that make it possible their practical implementation for manufacturing acoustic/elastic devices. With this purpose a formalism of the effective medium theory (EMT) was developed, in the limit of wavelength and low fill fractions. With the developed EMT, the scattering of simple spherical inclusions, coated and doubly coated in different host substrates were studied. The results showed the existence of resonant bands in the coefficients of the T matrix related to monopolar, dipolar and quadrupolar modes. Composite materials consisting of simple, coated or double coated spheres were analyzed using the EMT formalism. The results showed that the negative values of elastic parameters in these materials are completely related to resonant effects of the spheres of inclusion. Elastic and acoustic Metamaterials were designed by overlaying two or more different composites, each with different properties, such that the overall effect on the metamaterial shows the desired features defined in the initial project. The elastic metamaterial was designed by overlapping three different composites of different spherical inclusions. This metamaterial shows negative refractive index in the region of 2 kHz, in a band of width of 80 Hz. The acoustic metamaterial was designed by overlapping two composites of different spherical inclusions. This material shows negative refractive index in the region of 7 kHz, in a band of width of 500 Hz. The geometries and materials used in the design of these Metamaterials are affordable and easy to handle, which will facilitate their future fabrication in the laboratory. The results obtained in this study suggest the possibility to manufacture these metamaterials in the laboratory and use them in the control of acoustic, elastic and seismic waves, as well as in the design of invisible cloak.

Experiments investigating complex flows in rod bundles with spacer grids that have mixing devices (such as flow mixing vanes) have mostly been performed using single-point measurements. Although these measurements allow local comparisons of experimental and numerical data they provide little insight because the discrepancies can be due to the integrated effects of many complex flow phenomena such as wake-wake, wake-vane, and vane-boundary layer interactions occurring simultaneously in a complex flow environment. In order to validate the simulations results, detailed comparison with experimental data must be done. This work describes an experimental database obtained using Time Resolved Particle Image Velocimetry (TR-PIV) measurements within a 5 x 5 rod bundle with spacer-grids. Measurements were performed using two different grid designs. One typical of Boiling Water Reactors (BWR) with swirl type mixing vanes and the other typical of Pressurized Water Reactors (PWR) with split type mixing vanes. High quality data was obtained in the vicinity of the grid using the multi-scale approach. One of the unique characteristic of this set-up is the use of the Matched Index of Refraction (MIR) technique employed in this investigation. This approach allows the use of high temporal and spatial non-intrusive dynamic measurement techniques to investigate the flow evolution below and immediately above the spacer. The experimental data presented includes explanation of the various cases tested such as test rig dimensions, measurement zones, the test equipment and the boundary conditions in order to provide appropriate data for comparison with Computational Fluid Dynamics (CFD) simulations. Turbulence parameters of the obtained data are analyzed in order to gain insight of the physical phenomena. The shape of the velocity profile at various distances from the spacer show important modifications passing the grid which delineates the significant effects of the presence of the grid spacer. Influence of the vanes wake in the global velocity was quantified to be up to a distance of 4 hydraulic diameters from the edge of the grid.Spatial and temporal correlations in the two measured dimensions were performed to quantify the time and length scales present in the flow in the vicinity of the grids and its influence in the flow modification induced by the vanes. Detection of vortex cores was performed using the vorticity, swirl strength and Galilean decomposition approach. The resulted cores were then tracked in time, in order to observe the evolution of the structures under the influence of the vanes for each grid. Vortex stretching was quantified in order to gain insight of the energy dissipation process normally associated with the phenomena. This work presents data in a single-phase flow situation and an analysis of these data for understanding complex flow structure. This data provide for the first time detailed temporal velocity full field which can be used to validate CFD codes.

This thesis describes the design, construction and testing of a new interferometer for the absolute measurement of length standards. It is assumed that this study mainly formed of three parts. Firstly, it starts with an introduction to the subject of length standards and length measurement by interferometry. The design of the new interferometer is given in detail, including the stable lasers used as light sources, fiber, optical and opto-mechanical components. In the second part of this study, the mechanical construction of the interferometer chamber is presented with temperature stabilization and controlling system. The temperature variations inside the chamber at different points in air and along the surface of the length standard are given. After that, the techniques for measurement of the refractive index of the air inside the interferometer chamber are summarized. In the last part of the thesis, a review of fringe analysis techniques is given, with an emphasis on 5 position phase-stepping algorithms. The data processing of images digitized in the interferometer is described, including the techniques developed for discontinuity removal and surface fitting. The measurement of the variation in length and flatness of the measuring faces of the length standards is described and the experimental results are given. The automated method of multiple wavelength-exact fractions is used to combine phase measurements at three wavelengths to allow accurate calculation of the length of the length standards. The experimental results are given for length standards. The uncertainty budget of whole system is calculated and presented in a table.

The work reported in this thesis has been carried out in the following two areas of Optical metrology: 1. Measurement and correction of prism angles 2. Measurement of refractive indices using a spectrograph. The prism angles are conventionally tested by mechanical bevel protractors, autocol-limators (angle dekkors), simple interference techniques and interferometers. All these methods have their own limitations either in accuracy or in terms of cost. Mechanical methods are usually employed to measure the angles of prisms. Interference techniques and interferometers are also used but they need optically polished components. For both mechanical and simple interference methods of testing, it is essential to fabricate more than a single component in number. The process of building interferometers or purchasing interferometers, angle dekkors and standard angle gauges is not cost effective for many research laboratories, and medium scale industries. To overcome these difficulties simple and inexpensive methods without sacrificing the accuracy in the bargain are suggested for the measurement of prism angles, based on the principles of reflection of light. The refractive indices of prism materials for invisible and weaker spectral lines are usually determined from spectrograms using dispersion formulae and numerical interpolation techniques. In these methods, the accuracy of the results depends on the accuracy of determining the constants of the dispersion formulae. A simple experimental technique, using a spectrograph, is devised for the measurement of refractive indices of solids and liquids both for visible and invisible spectral lines (wavelengths). The thesis has been divided into six chapters. The first chapter starts with the general introduction. The second chapter presents the literature review of the existing methods for angle and refractive index measurements. The third chapter describes the proposed new techniques for prism angle measurements. The fourth chapter presents the experimental results of angle measurements, and the discussion of the accuracy of the results. This chapter also gives the scope for further research. The fifth chapter describes a newly proposed technique for measuring refractive indices and the experimental results. This chapter also gives the scope for further research. The summary of the results, conclusions, and suggestions for further work are presented in chapter six.

Multimode devices play an increasingly important role in both communication and sensing systems. Mode division multiplexing (MDM) in multimode fiber (MMF) is becoming a promising method to further increase the capacity of optical transmission link with a controllable mode coupler. Similarly, optic sensors based on core-cladding-mode interference can be widely used in measurement of refractive index (RI), temperature and strain. Fiber Bragg gratings (FBGs) in single mode operation have been extensively studied as in-line optical components for both communication and sensing applications. In recent years, research has been extended to FBGs in few-mode operation as mode couplers in MDM applications. Experimentally, mode conversion from fundamental linear polarization (LP) mode LP01 to higher order LP11 mode in two-mode FBG (TMFBG) has been observed. Index asymmetry and electric field distortion induced by ultraviolet (UV) side illumination in fabrication of FBG make the two modes no longer orthogonal. However, its spectrum analysis mainly depends on experimental data and software simulation using the complex finite element method (FEM). Here a simpler theoretical model based on coupled mode theory (CMT) and Runge-Kutta method (RKM) is proposed. An analytical expression of the mode coupling coefficient is derived and the modeling results match very well with experimental data. Abrupt fiber tapers allow power transfer between core and cladding modes and show promise as RI sensing components when two abrupt tapers are cascaded into an in-line Mach-Zehnder interferometer (MZI). The main advantage of the MZI taper sensor is its low manufacturing cost. However, the optical spectrum analyzer (OSA) used as the receiver and demodulation device in the conventional setup is still expensive. Three simplified schemes of fiber taper MZI RI sensor systems are designed and demonstrated experimentally. The transmitter and the demodulation devices for the three schemes are a single wavelength laser and a photodetector (PD), two modulated lasers and a PD together with data acquisition and processing module, and a broadband source (BBS) and a PD together with matched MZI, respectively. In all those implementations OSA is not required, which significantly lowers the cost and leads to easy integration. Although extra modulation/demodulation devices are required, the second implementation has the best performance. Automatic operation is realized by LabVIEW programming. High sensitivity (2371 mV/RI unit (RIU)) and high stability are achieved experimentally. Those new schemes have great potential to be applied to other interferometric optic sensor systems. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2014-05-09 11:44:44.837

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Orientador: Keizo Yukimitu / Banca: Sandro Márcio Lima / Banca: Luis Humberto da Cunha Andrade / Resumo: Os vidros teluritos são materiais que apresentam importantes propriedades ópticas de interesse aplicativo na área da fotônica. Uma das propriedades interessantes de tal vidro é o elevado índice de refração. De acordo com estudos realizados, o incremento de óxidos modificadores de rede nos vidros teluritos provoca o aumento do índice de refração em tal material, devido à mudanças estruturais ocorridas. Com esse intuito, sintetizamos amostras de vidros teluritos com nióbio, de composição 80TeO2-(20-x)Li2O-xNb2O5 (x = 0, 5, 10 e 15). Para caracterização das amostras foram realizadas medidas de espectroscopia na região do infravermelho (FTIR) e UV-Vis, espectroscopia Raman e Difratometria de Raios-X. Foram realizadas medidas de índice de refração das amostras para verificar a influência da concentração de óxido de nióbio acerca deste índice. A difratometria de Raios-X confirmou o estado amorfo das amostras. Os estudos de caracterização (por espectroscopia no infravermelho e Raman) mostraram que a inserção de óxido de nióbio deslocou, para maiores freqüências, as bandas de absorção características dos grupos TeO4 e NbO4 provocadas por mudanças estruturais e pela incorporação de oxigênios não-ligantes. A espectroscopia na região ultravioleta-visível mostrou uma tendência no aumento do comprimento de onda de corte com o acréscimo de óxido de nióbio, o qual pode estar associado a alguma mudança estrutural. As medidas de índice de refração mostraram que, de acordo com o incremento de óxidos modificadores, este índice aumentou. Tal fato se deve à transição de oxigênios nãoligantes para ligantes e à polarização das ligações Te-O dos grupos TeO4 e ligações Nb-O dos grupos NbO4, pois essas ligações apresentam maiores momentos de dipolo elétrico que as demais. / Abstract: Tellurite glasses are important materials which have interesting optical properties application in photonics mainly due to its high refractive index. According to studies, the increase of network modifier oxides in tellurite glasses can increase the refractive index in such material, due to structural changes. For this purpose, samples with niobium tellurite glasses of composition 80TeO2-(20-x)Li2O-xNb2O5 (x = 0, 5, 10 and 15) were synthesized and characterized by (FTIR) and UV-Vis spectroscopy, Raman spectroscopy and X-ray diffraction. The influence of niobium oxide concentration to the refractive index was also investigated. The characterization studies (infrared spectroscopy and Raman) showed that the insertion of niobium oxide shifted the characteristic absorption bands of groups TeO4 and NbO4 to higher frequencies. The structural changes are due to incorporation of non-bridging oxygen. The UV-Vis spectra showed a trend of increasing the wavelength of UV-Vis cut-off with the addition of niobium oxide and this increase may be linked to structural changes. The X-ray diffraction confirmed the amorphous state of samples. The measurement of refractive index showed that, in accordance with the increment of oxide modifiers, this index increased. This is due to the transition from non-bridging oxygen to bridging oxygen and the polarization of the Te-O bonds of the groups TeO4 and links Nb-O of the NbO4 groups because these bonds have higher dipole moments than the others. / Mestre

Inspection of optical components is essential to assure the quality and performance of optical systems. Evaluation of optical components includes metrology measurements of surface topography. It also requires optical measurements including refractive index, thin film thickness, reflectivity and transmission. The dispersion characteristics of optical constants including refractive index are also required. Hence, various instruments are used to make these measurements in research laboratories and for quality assurance. Clearly, it would be a significant advantage and cost saving if a technique was developed that could combine surface metrology with optical measurements. {Coherence Scanning Interferometry} (CSI) (also referred to as {Scanning White Light Interferometry} (SWLI)) has been used widely to measure surface topography with sub-nanometre vertical resolution. One of the benefits of the CSI is that the technique is non-contacting and hence non-destructive. Thus the test surfaces are not affected by the measurement using a CSI instrument whereas damage to the surfaces can occur when using traditional contact methods such as stylus profilometry. However use of CSI is geometrically limited to small areas ($\lesssim 10 \times 10$ mm) with gentle slopes ($\lesssim \ang{40}$) because of the numerical aperture of objective lens whereas stylus profilometry works well with larger areas and higher slopes due to the range of motion of the gauge and the traverse unit. Since the CSI technique is optical and involves light reflection and interference it is possible to extend the technique for the measurement of the thickness of transparent films, the roughness of surfaces buried beneath thin films or interfacial surfaces. It may also be used to determine spectral complex refractive index. This thesis provides an analytical framework of new methods to obtain complex refractive index in a visible light domain and interfacial surface roughness (ISR). It also provides experimental verification of these new capabilities using actual thin film model systems. The original Helical Complex Field (HCF) function theory is presented followed by its existing extensions that enable determination of complex refractive index and interfacial surface roughness. Further theoretical extensions of the HCF theory are also provided: A novel theory to determine the refractive index of a (semi-)transparent film is developed to address the constraint of the current HCF theory that restricted its use to opaque materials; Another novel theory is provided to measure ISR with noise compensation, which avoids erroneous surface roughness caused by the numerical optimisation affected by the existence of noise. The effectiveness of the ISR measurement with noise compensation has been verified using a number of computer simulations. Stylus profilometry is a well established method to provide a profile and has been used extensively as a 'reference' for other techniques. It normally provides a profile on which the roughness and the waviness are computed. Extension of the stylus profilometry technique to areal measurement of asymmetrical surfaces, namely raster scan measurement, requires a system to include error compensation between each traverse. The system errors and the random errors need to be separately understood particular when the measurement of a surface with nanometre-order accuracy is required. In this thesis a mathematical model to locate a stylus tip considering five mechanical errors occurring in a common raster scan profilometer is provided. Based on the model, the simulator which provides an areal measurement of a sphere was developed. The simulator clarified the relationship between the Zernike coefficients obtained from the form residual and the size of the errors in the form of partial derivatives of Zernike coefficients with respect to the errors. This provides theoretical support to the empirical knowledge of the relationship between the coefficients and the errors. Furthermore, a method to determine the size of errors directly from Zernike coefficients is proposed supported by simulations. Some of the error parameters were accurately determined avoiding iterative computation with this method whereas the errors are currently being determined by iterative computation.

Made available in DSpace on 2014-06-11T19:25:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-08-20Bitstream added on 2014-06-13T20:53:38Z : No. of bitstreams: 1 capanemajunior_wa_me_ilha.pdf: 1306042 bytes, checksum: d90e8cb73761f2190b4d6d40b6bc20b3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foram estudadas as propriedades ópticas de vidros teluretos do sistema (20-x)Li2O-80TeO2-xTiO2 com x = 0, 5, 10 e 15 mol%. Foram preparadas amostras para cada uma das composições através do convencional método de “meltquenting”. Medimos, para cada amostra, o espectro de infravermelho e o espectro na faixa do ultravioleta-visível. Também obtemos os valores de índice de refração de cada amostra para diversos comprimentos de onda na faixa do visível. Para tanto, utilizamos um interferômetro de Michelson-Morley modificado. Medidas de densidade foram feitas utilizando-se o convencional método de Arquimedes. Por fim, foram feitas medidas do coeficiente térmico do caminho óptico através da interferometria. A análise estrutural foi feita através do espectro de infravermelho. Pode-se observar a tendência à formação de pirâmides trigonais em substituição às bipirâmides (encontradas no TeO2 cristalino) quando aumentamos a porcentagem de óxido de lítio. Uma análise qualitativa da absorção na faixa de interesse em comunicações ópticas (~1500 nm) foi feita através do espectro de infravermelho próximo, mostrando que nesta faixa temos a predominância do espalhamento Rayleigh, com o coeficiente de absorção proporcional a λ-4. Usando os dados da espectroscopia na faixa ultravioleta-visível foi possível observar a mudança das freqüências de corte para cada composição e ainda calcular a energia de gap e a energia de cauda de Urbach. Através do modelo clássico de osciladores harmônicos forçados de Wemple, os resultados de índice de refração foram interpretados. Buscou-se ainda relacionar as mudanças observadas para os valores medidos para cada composição com possíveis mudanças estruturais. Concluímos, usando as considerações de Wemple, que o aumento... / In this work had been studied tellurite glasses’s the optic properties of the system (20-x) Li2O-80TeO2-xTiO2 with x = 0, 5, 10 and 15 mol%. Samples for each one of the compositions through the conventional method of melt-quenting had been prepared. We measure, for each sample, the infra-red ray specter and the specter in the band of the ultraviolet-visible one. Also we get the values of refractive index of each sample for diverse wave lengths in the visible band. For in such a way, we use a modified interferometer of Michelson-Morley. Measures of density had been made using the conventional method of Archimedes. Finally, they had been made measured of the thermal coefficient of the optic way through the interferometry. The structural analysis was made through the infra-red ray specter. The trend to the formation of trigonais pyramids in substitution to the bipyramids can be observed (found in the crystalline TeO2) when increases the lithium oxide percentage. A qualitative analysis of the absorption in the band of interest in optic communications (~1500 nm) was made through the infra-red ray specter, showing that in this band we have the predominance of the Rayleigh scattering, with the coefficient of absorption proportional to λ-4. Using the data of the spectroscopy in the ultraviolet-visible band to each composition was possible to observe the change of the cut-off frequencies and still to calculate the energy of gap and the energy of Urbach. Through the classic model of forced harmonic oscillators of Wemple, the results of refractive index had been interpreted. We still searched to relate the changes observed for the values measured for each composition with possible structural changes. We conclude, using the considerations of Wemple, that the increase for the values of... (Complete abstract click electronic access below)