This thesis is concerned with the material processing, photophysical and third-order nonlinear optical responses, and applications of a set of conjugated polymers in the telecommunication regions. Polyacetylene-based third-order nonlinear optical materials were chosen as candidates for all-optical signal and image processing. Substituted polyacetylenes were obtained using ring-opening metathesis polymerization of mono-substituted cyclooctatetraenes. Polymerization and processing conditions have been developed to generate thick, large-area films possessing large third-order nonlinearities in the telecommunication bands. The good optical quality of a 200 μm thick substituted polyacetylene film allowed for image correlation via off-resonant degenerated four-wave mixing with improved diffraction efficiency. Poly(2-methoxy-5-(2-ethyl-hexyloxy)-(phenylene vinylene)) (MEH-PPV) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) composites showed strong nonlinear absorption and potential as optical limiters in the region of 700-900 nm. High optical quality, thick film of MEH-PPV:PCBM with the plasticizer dioctylphthalate (DOP) were made. Optical limiting of femtosecond and nanosecond pulses in the near infrared on these composites showed strong power suppression over a broad temporal regime. Femtosecond and nanosecond transient studies on the same thick MEH-PPV:PCBM:DOP composite films and the experimental results showed evidence for the photogeneration of radical ions as being responsible for the enhanced nonlinear absorption and strong optical suppression in the near infrared. Dithienopyrrole-based donor-acceptor copolymers with narrow bandgap showed strong nonlinear absorption and potential as optical limiters in the telecommunication wavelengths. Molecular engineering was applied to manipulate the spectral overlap of two-photon absorption and subsequent nonlinear absorptions. Femtosecond transient spectroscopy showed near infrared transient absorption and 22 - 61% yields of photogenerated charge-transfer species depending on donor-acceptor coupling strength. Torsional fluctuations of the backbone structure potentially affected the excited state behavior. Evidence suggests that ultrafast relaxation occurs to ground state and to long-lived charge-transfer state from the initially excited state. The dispersion of nonlinear absorption measured using the Z-scan method revealed large two-photon absorption cross sections of these polymers in the telecommunication region. Large suppression of nanosecond pulses at 1064 nm was achieved.

This research lays the foundation of a highly simplified maskless micro-fabrication technique which involves incorporation of laser direct writing technique combined with fountain pen based micro-patterning method to fabricate polymer-based Mach-Zehnder interferometer sensor arrays' prototype for chemical/biological sensing applications. The research provides methodology that focuses on maskless technology, allowing the definition and modification of geometric patterns through the programming of computer software, in contrast to the conventional mask-based photolithographic approach, in which a photomask must be produced before the device is fabricated. The finished waveguide sensors are evaluated on the basis of their performance as general interferometers. The waveguide developed using the fountain pen-based micro-patterning system is compared with the waveguide developed using the current technique of spin coating method for patterning of upper cladding of the waveguide. The resulting output power profile of the waveguides is generated to confirm their functionality as general interferometers. The results obtained are used to confirm the functionality of the simplified micro-fabrication technique for fabricating integrated optical polymer-based sensors and sensor arrays for chemical/biological sensing applications.

Orientador: Julio Roberto Bartoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T22:28:46Z (GMT). No. of bitstreams: 1 Giacon_VirginiaMansanares_M.pdf: 2837652 bytes, checksum: cc8b7a2c68b1b5f694c6e06c1feb5bfb (MD5) Previous issue date: 2004 / Resumo: Materiais poliméricos são alternativas aos materiais inorgânicos na fabricação de dispositivos ópticos como guias de ondas e fibras ópticas (POF) para transmissão de luz ou sinal. Isso porque, a estrutura molecular dos polímeros pode ser modelada com versatilidade, contribuindo para obter materiais com índices de refração (?) distintos, baixo custo e fácil processamento. Esses dispositivos são constituídos basicamente de um núcleo e uma camada externa, casca ou cladding. Os materiais para casca são usualmente à base de polímeros fluorados. Neste trabalho estudou-se a modificação de superfície de filmes de poli (metacrilato de metila), PMMA, utilizando-se a técnica de Polimerização por Plasma de gás fluorado. Filmes de PMMA com espessuras de 60 µm foram obtidos por spin coating a partir de uma solução de MIBK e Xileno (30% em massa de PMMA). Seguindo dois planejamentos fatoriais, em diferentes condições de pressão (0,5 a 2 torr) e potência (60 a 150 W), os filmes foram expostos ao plasma de CHF3. As superfícies desses filmes foram caracterizadas através de espectroscopia no infravermelho (FTIR/ATR), ângulo de contato de molhamento, microscopia de força atômica (AFM), espectroscopia XPS e análise gravimétrica. A fluoração da superfície dos filmes de PMMA expostos ao plasma foi confirmada por análises de XPS (razão atômica F/C=1,12) e pelo aumento do ângulo de contato de 700(PMMA original) para 100°. O planejamento fatorial mostrou que a pressão é um fator significante (95% confiança) no seu nível mínimo (0,5 torr) para aumentar o ângulo de contato. Análises via FTIR-ATR mostraram alterações nas intensidades de absorção dos grupos C=O e C-O do PMMA, diminuindo significativamente a razão C=O/C-O após o plasma. Análises de AFM mostraram um tolerável aumento da rugosidade da superfície dos filmes após o tratamento. A espessura da camada fluorada, estimada por gravimetria, foi de aproximadamente 0,11 µm. Essa camada deve apresentar um índice de refração menor que o PMMA, inferido pelo alto teor de flúor na superfície dos filmes, determinado pelas análises XPS / Abstract: Polymeric materials are alternative to inorganic materials for production of optical devices as waveguides and optical fibers (POF) for light transmission. This because the molecular structure of polymers can be versatile modeled, giving materials with different refractive indices, low cost and easy processing. These devices are basically consisted by core with an external layer, cladding, of low refractive index (?) allowing light propagation into the core. The cladding materials are usually made of fluorinated polymers. In this work the surface modification of Poly (methylmethacrylate), PMMA, was studied using the plasma polymerization technique. Polymeric films of 60µm thickness were obtained by spin coating using a solution of MIBK and Xylene (30 wt% PMMA). The films were exposed to CHF3 plasma. The processing conditions followed two factorial experimental designs for gas pressure (0.5 - 2 torr) and plasma power (60 - 120 W). The surfaces of the films were characterized using infrared spectroscopy (FTIR/ A TR), contact angle of wetting, atomic force microscopy, XPS spectroscopy and gravimetry. The surface fluorination of PMMA films was confirmed by XPS analysis and also inferred due to the increase on contact angle from 70° (PMMA original) to 100°. The factorial analysis indicated that pressure is a significant factor to increase the contact angle at the lower level 0.5 torr (95% of confidence). FTIR/ATR analysis showed significant alteration on the absorbance intensity of the C=O/C-O groups after plasma. AFM topography analysis showed a tolerable increase on roughness of the surface of plasma exposed films. The thickness of the fluorinated layer was approximately 0.11 µm (estimated by gravimetry). This fluorinated layer should have lower refractive index than the PMMA, due to the high fluorine content on the film surface (F/C ratio), measured by XPS analysis / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Orientador: Julio Roberto Bartoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T09:00:39Z (GMT). No. of bitstreams: 1 Padilha_GiovanadaSilva_M.pdf: 1555922 bytes, checksum: 035b74427e55cfdd28217830ff384c88 (MD5) Previous issue date: 2005 / Resumo: Dispositivos ópticos poliméricos têm sido promissores para aplicação em comunicações, principalmente na utilização em redes de curta distância devido ao fácil processamento e baixo custo quando comparado aos materiais ópticos fabricados com sílica. Na fabricação de um dispositivo óptico é imprescindível que o índice de refração do núcleo seja maior do que o da casca para que o sinal seja transmitido pelo dispositivo. Algumas técnicas de tratamento superficiais são muito comuns para obter diferentes índices de refração entre os materiais, entre elas a fluoração por plasma, seja por reações de deposição ou substituição, formando-se uma camada de polímero fluorado sobre um substrato polimérico com índice de refração modificado. Neste trabalho, estudou-se a modificação da superfície de filmes de poli (metacrilato de metila) (PMMA), usando a técnica de polimerização por plasma de gás fluorado. Filmes de PMMA com espessura de 1 O _m foram obtidos por Spin-Coating a partir de uma solução de clorofórmio (15,36% em massa de PMMA). Os filmes foram expostos ao plasma de CHF3 seguindo dois planejamentos fatoriais em diferentes níveis de pressão e tempo. A superfície dos filmes ópticos fluorados produzidos foi caracterizada através das técnicas: gravimetria, espectroscopia no infravermelho (FTIR-A TR), ângulo de contato de molhamento, microscopia óptica, microscopia eletrônica de varredura (MEV), microscopia de força atômica (AFM) e perfilometria. A fluoração da superfície dos filmes de PMMA pode ser inferida pelo aumento do ângulo de contato em todas as condições experimentais e confirmadas através das análises de FTIR-A TR. As análises gravimétricas apresentaram aumento da camada fluorada sobre o filme de PMMA em toàas as condições de processo, estimando a maior espessura próxima a 1,55 _m em 0,7 torr e 40 minutos de plasma. A análise estatística mostrou que a pressão e o tempo foram variáveis significativas (95% de confiança) para o crescimento de camada polimérica fluorada. Análises de MEV apresentaram uma camada fluorada bem definida e presença do elemento flúor com a análise de EDS. A rugosidade dos filmes ópticos fluorados foi de 200 Á, bastante satisfatório para cladding com 1,55 _m de espessura / Abstract: Polymeric optical devices have been promising for application in communications, mainly for local networks due to easy processing and low cost compared to the optical materials made silica. In the production of an optical device it is indispensable the difference between the refraction index of the core and the cladding. The refractive index of the core should be larger than the one of the cladding so that the signal is transmitted by the device. Some techniques of surface treatment are very common to obtain different refractive index among the materials, among them plasma fluorination that either allow deposition reaction of a layer of fluorinated polymers the substrate with refractive index modified. In this work, it was studied the modification of the surface of poly (methyl methacrylate) (PMMA) films, with the technique of plasma polymerization. Films of PMMA with thickness of 1 O _m were obtained by Spin-Coating starting from a chloroform solution (15.36% wt% PMMA). The films were exposed to the plasma of CHF3 following two factorial experimental designs at different levels of pressure and time. The surface of the films was characterized through the techniques: gravimetry, infrared spectroscopy (FTIR-ATR), contact angle of wetting, optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM) and scan profile. The surface fluorination of PMMA films can be inferred by the increase of the contact angle in all of the experimental conditions and confirmed with the analyses of FTIR-ATR. Gravimetry showed an increase of the layer of fluorinated polymer onto PMMA films, being 1.55 _m the largest thickness at 0.7 torr and 40 minutes of plasma. The factorial analysis showed that pressure and time were significant (95% of confidence) for the growth of the fluorinated polymeric layer. Analyses of SEM showed a layer of fluorinated polymer well defined and presence of the fluorine element by EDS analysis. The roughness of the films fluorinated polymers was around of 200 A, quite satisfactory for cladding of 1.55 micro m of thickness / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química