A rigorous analysis based upon the extinction theorem is presented to study anomalous resonance effects from single- and multilayer-overcoated, low-efficiency diffraction gratings. Anomalously high diffraction efficiency at resonance results from the coupling of the incident beam into guided waves that can be propagated within the composite structure. Both the traditional characteristic matrix technique and a recursive or R-matrix propagation technique are presented. The R-matrix propagation algorithm was found to be stable numerically, and computational results agree favorably with both experimental and other theoretical work. Numerical results are presented in order to investigate the influence of certain parameters (i.e., groove depth and shape and the number of high- and low-index overlayers) on the diffraction efficiency at resonance. In this analysis, a wavelength of 0.6328 μm and grating period of 0.7 μm were chosen so that only a -1 diffracted order other than the specular is reflected from the gratings. Perfect transfer of the grating relief to the film boundaries does not occur in all instances; it depends on the grating and film characteristics together with the conditions during deposition. Investigated in this work is the effect of nonreplication of the grating profile at film interfaces on anomalous diffraction; a transition from trapezoidal profile at the grating substrate to a rounded relief at the top surface of the multilayer structure is assumed. For the cases studied, it was found that nonreplication has the effect of reducing the strength of the resonance outcoupling. Finally, experimental results on anomalous resonance effects for multilayer-coated gratings are presented. Good agreement with computational results was attained.

Neste projeto foram desenvolvidos elementos ópticos difrativos fabricados em vidro óptico com modulação de fase, elementos fabricados em silício e em Diamond Like Carbon (carbono tipo diamante) com modulação completa de fase e amplitude. O vidro óptico começa a transmitir em 277 nm (ultravioleta) e vai até o infravermelho próximo (2200 nm) da mesma maneira que o Diamond Like Carbon (que começa a transmitir em 330 nm). Já o silício é um material que começa a transmitir no infravermelho próximo (em torno de 980 nm) e vai até o infravermelho médio (16000 nm). Tanto para o Diamond Like Carbon como para o vidro óptico, optou-se por desenvolver dispositivos que operem para um comprimento de onda de 632,8 nm. Já os elementos ópticos difrativos baseados em silício foram fabricados para operar em 2 comprimentos de onda: 1550 nm e 10600 nm. Para os dispositivos fabricados, foram utilizadas etapas de limpeza de substrato, de deposição de filmes, de litografia e de corrosão úmida e por plasma. A etapa de corrosão por plasma foi o principal objeto de estudo do processo de fabricação com o intuito de otmilizá-la. Foram feitos estudos de taxa de corrosão dos materiais com diferentes composições gasosas com a finalidade de se encontrar os parâmetros mais adequados para otimizar a fabricação dos dispositivos. As melhores condições de processo para o vidro corroído com plasma de CF4 são pressão de 100 mTorr e potência de 400 W, para o Diamond Like Carbon corroído com plasma de O2, pressão de 25 mTorr e potência de 50 W e para o silício corroído com plasma de SF6 os parâmetros são pressão de 100 mTorr e potência de 150 W. Análises ópticas dos elementos, fabricados com esses processos foram realizadas. Na análise óptica dos dispositivos de vidro com dois e quatro níveis de modulação de fase ficou evidente que os elementos ópticos apresentaram bom desempenho devido à uniformidade da intensidade da luz projetada nas imagens e da baixa intensidade do ponto de ordem zero, além das imagens estarem bem focadas e definidas. Para os dispositivos fabricados em Diamond Like Carbon foram formadas imagens bem definidas e focadas. Em uma análise óptica da rugosidade RMS dos filmes finos de Diamond Like Carbon através da obtenção da Reflectância Total e da Reflectância Difusa, foi encontrado um valor de 18,8 nm, o qual se encontra bem abaixo do limite de 63 nm, o que faz com que o dispositivo gere uma imagem otimizada. / In this project it has been manufactured diffractive optical elements in three materials, optical glass, Diamond Like Carbon (DLC) and silicon. These elements were applied in phase modulation devices. The extra advantage of silicon and DLC were the amplitude modulation in visible and ultra-violet spectra respectively. The optic glass starts to transmit at the wavelength 277 nm (UV light) and goes till the near infrared in the same way that the Diamond Like Carbon (that starts to transmit in 330 nm). Silicon is a material that starts to transmit in the near infrared (980 nm) and goes till the middle infrared (16000 nm). Both, DLC and optic glass, was opted to developing devices that operate for a 632,8 nm wavelength. Diffractive Optical Elements silicon based had been manufactured to operate in two wavelengths: 1550 nm and 10600 nm. For the manufactured diffractive optical elements, were used process stages of substrate cleanness, films deposition, lithography and hybrid wet and dry plasma etching. The plasma etching stage was the most studied manufacturing process, aiming of optimized it. For this, some studies of materials etching rate with different gases were made with the purpose to find the more adequate parameters of Radio Frequency power and pressure to reduce the process time to obtain the necessary thickness and low surface roughness. The best conditions of plasma etching process were 100 mTorr pressure and Radio Frequency power of 400 W for the glass, 25 mTorr pressure and Radio Frequency power 50 W for the Diamond Like Carbon and the parameters are 100 mTorr pressure and Radio Frequency power 150 W for silicon. Optical analyses of the diffractive optical elements manufactured with these processes had been realized. In the optical analysis of the glass devices with two and four levels of phase modulation was evident that the optic elements had good performance due to uniformity of the projected light intensity in the images and low intensity of the zero order spot, as well the images are focused and defined. For elements manufactured in Diamond Like Carbon, defined and well-focused images had been formed. In an optic analysis of Diamond Like Carbon thin films RMS roughness through the Total Reflectance and the Diffuse Reflectance, was found a value of 18,8 nm roughness, which is below 63 nm limit, what do that the EOD generates an optimized image.

Neste projeto foram desenvolvidos elementos ópticos difrativos fabricados em vidro óptico com modulação de fase, elementos fabricados em silício e em Diamond Like Carbon (carbono tipo diamante) com modulação completa de fase e amplitude. O vidro óptico começa a transmitir em 277 nm (ultravioleta) e vai até o infravermelho próximo (2200 nm) da mesma maneira que o Diamond Like Carbon (que começa a transmitir em 330 nm). Já o silício é um material que começa a transmitir no infravermelho próximo (em torno de 980 nm) e vai até o infravermelho médio (16000 nm). Tanto para o Diamond Like Carbon como para o vidro óptico, optou-se por desenvolver dispositivos que operem para um comprimento de onda de 632,8 nm. Já os elementos ópticos difrativos baseados em silício foram fabricados para operar em 2 comprimentos de onda: 1550 nm e 10600 nm. Para os dispositivos fabricados, foram utilizadas etapas de limpeza de substrato, de deposição de filmes, de litografia e de corrosão úmida e por plasma. A etapa de corrosão por plasma foi o principal objeto de estudo do processo de fabricação com o intuito de otmilizá-la. Foram feitos estudos de taxa de corrosão dos materiais com diferentes composições gasosas com a finalidade de se encontrar os parâmetros mais adequados para otimizar a fabricação dos dispositivos. As melhores condições de processo para o vidro corroído com plasma de CF4 são pressão de 100 mTorr e potência de 400 W, para o Diamond Like Carbon corroído com plasma de O2, pressão de 25 mTorr e potência de 50 W e para o silício corroído com plasma de SF6 os parâmetros são pressão de 100 mTorr e potência de 150 W. Análises ópticas dos elementos, fabricados com esses processos foram realizadas. Na análise óptica dos dispositivos de vidro com dois e quatro níveis de modulação de fase ficou evidente que os elementos ópticos apresentaram bom desempenho devido à uniformidade da intensidade da luz projetada nas imagens e da baixa intensidade do ponto de ordem zero, além das imagens estarem bem focadas e definidas. Para os dispositivos fabricados em Diamond Like Carbon foram formadas imagens bem definidas e focadas. Em uma análise óptica da rugosidade RMS dos filmes finos de Diamond Like Carbon através da obtenção da Reflectância Total e da Reflectância Difusa, foi encontrado um valor de 18,8 nm, o qual se encontra bem abaixo do limite de 63 nm, o que faz com que o dispositivo gere uma imagem otimizada. / In this project it has been manufactured diffractive optical elements in three materials, optical glass, Diamond Like Carbon (DLC) and silicon. These elements were applied in phase modulation devices. The extra advantage of silicon and DLC were the amplitude modulation in visible and ultra-violet spectra respectively. The optic glass starts to transmit at the wavelength 277 nm (UV light) and goes till the near infrared in the same way that the Diamond Like Carbon (that starts to transmit in 330 nm). Silicon is a material that starts to transmit in the near infrared (980 nm) and goes till the middle infrared (16000 nm). Both, DLC and optic glass, was opted to developing devices that operate for a 632,8 nm wavelength. Diffractive Optical Elements silicon based had been manufactured to operate in two wavelengths: 1550 nm and 10600 nm. For the manufactured diffractive optical elements, were used process stages of substrate cleanness, films deposition, lithography and hybrid wet and dry plasma etching. The plasma etching stage was the most studied manufacturing process, aiming of optimized it. For this, some studies of materials etching rate with different gases were made with the purpose to find the more adequate parameters of Radio Frequency power and pressure to reduce the process time to obtain the necessary thickness and low surface roughness. The best conditions of plasma etching process were 100 mTorr pressure and Radio Frequency power of 400 W for the glass, 25 mTorr pressure and Radio Frequency power 50 W for the Diamond Like Carbon and the parameters are 100 mTorr pressure and Radio Frequency power 150 W for silicon. Optical analyses of the diffractive optical elements manufactured with these processes had been realized. In the optical analysis of the glass devices with two and four levels of phase modulation was evident that the optic elements had good performance due to uniformity of the projected light intensity in the images and low intensity of the zero order spot, as well the images are focused and defined. For elements manufactured in Diamond Like Carbon, defined and well-focused images had been formed. In an optic analysis of Diamond Like Carbon thin films RMS roughness through the Total Reflectance and the Diffuse Reflectance, was found a value of 18,8 nm roughness, which is below 63 nm limit, what do that the EOD generates an optimized image.

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The simulation of diffractive optical structures allows for the efficient testing of a large number of structures without having to actually fabricate these devices. Various forms of analysis of these structures have been done through computer programs in the past. However, programs that can actually design a structure to perform a given task are very limited in scope. Optimization of a structure can be a task that is very processor time intensive, particularly if the optimization space has many dimensions. This thesis describes the creation of a computer program that is able to find an optimal structure while maintaining a low-dimensional search space, thus greatly reducing the processor time required to find the solution. The program can design the optimal structure for a wide variety of planar optical devices that conform to the weakly-guiding approximation with an efficient code that incorporates the low-dimensional search space concept. This work is the first use of an electromagnetic field solver inside of an optimization loop for the design of an optimized diffractive-optic structure.

<p>This thesis addresses the subject of diffractive axicons inpartially coherent or oblique illumination. Design andcharacterization of the axicons are performed using asymptoticwave optics, employing the stationary-phase method to obtainapproximations of the diffraction integrals.</p><p>A design method for axicons in partially coherentillumination is derived. The method can be applied to anyincident illumination on radially symmetric Schell-model form.It provides analytical solutions for some specific cases, butfor most incident intensity and coherence distributions it canbe solved numerically to yield the desired on-axis intensity.In addition, a method for estimating the width of the focalline is provided. For coherent light, the design method isidentical to the old one based on energy conservation in raybundles. Since the new method is derived entirely from waveoptics, it both clarifies the old method and extends it topartially coherent light.</p><p>Oblique illumination of axicons, frequently encountered inapplications, causes degradation of the focal line. This changeis characterized, and from the asymptotic theory it is foundthat the focal line is described by an asteroid curve. Thewidth of the focal segment in oblique illumination isaccurately predicted, as confirmed by simulations andexperiments. It is also found that at a fixed angle, anelliptical axicon may be used to compensate for the adverseeffects of oblique illumination.</p><p><b>Keywords:</b>axicons, diffractive optics, coherence,asymptotic methods</p>

Recent experimental data on dijet cross section in diffractive photoproduction at HERA collider are analyzed with an emphasis on QCD factorization breaking effects. The possible sources of the contradiction in conclusions of H1 and ZEUS collaborations such as different hadronization corrections and different phase space of both analysis are studied.

Three types of focused ion beam machine: focused ion beam milling (FIB milling), focused ion beam lithography (FIB lithography), and focused ion beam direct deposition (FIB deposition), are described in detail to compare with electron beam lithography (EBL) and laser beam direct writing (LBW). A diffractive optical element (DOE) with continuous relief, six-annulus, relief depth of 1.17µm, and diameter of 65 µm, fabricated by use of the FIB milling, is cited as an example to illustrate the FIB milling and the comparison with the EBL and the LBW. Micro-cylindrical lens with dimension of 2.8µm×7.5µm×0.95µm in width, length and height, NA=0.2, is given as another fabrication example to illustrate the FIB deposition, which is a unique function for all the direct writing methods. They are all superiors to the EBL and the LBW in the case that optical elements need to be directly fabricated in local area of a device. / Singapore-MIT Alliance (SMA)