Soluble organic semiconductors have attracted interest due to their potential in making flexible and cheap electronics. Though their use is being implemented in electronics today, the conduction mechanism is still under investigation. In order to study the charge transport, this study examines the position, voltage, and frequency dependence of charge induced changes in far infrared absorption in soluble organic semiconductors in thin-film transistor structures. Measurements are compared to a simple model of a one-dimensional conductor which gives insight into the charge distribution and timing in devices. Main results of the study are dynamic measurements of charge taken by varying the frequency of the applied gate voltage while observing signal at one position within the transistor; mobility values obtained from a comparison to the one-dimensional model compare well with standard current-voltage measurements. Two small molecule soluble organic semiconductors were studied: 6,13 bis(triisopropylsilylethynyl)-pentacene and fluorinated 5,11 bis(triethylsilylethynyl) anthradithiophene.

Materiais poliméricos podem exibir propriedades ópticas não lineares (ONL), o que motiva hoje em dia, muitas pesquisas para sua aplicação em dispositivos optoeletrônicos. Neste trabalho descreve-se a preparação do copolímero do tipo grupo lateral (\"side-chain\") formado pelos monômeros metacrilato de metila (MMA) e monômeros metacrilato de metila ligado a molécula disperso vermelho 13 (MMA-DR13). Como a atividade óptica não-linear de segunda ordem dos materiais poliméricos está diretamente ligada a sua polarização elétrica dipolar (alinhamento de dipolos), o presente trabalho investiga as propriedades do copolímero MMA-DR13 através de medidas de condução elétrica, correntes de despolarização estimuladas termicamente (CDET) e medidas eletroópticas. As medidas de condução elétricas feitas a diferentes temperaturas mostraram a ser dependentes do tipo substratos/eletrodos, da polaridade de tensão e atmosferas na qual foram realizadas as medidas. Nas medidas de CDET observou-se que aparecem mais de um pico de corrente em função da temperatura. As medidas do coeficiente eletroóptico r13 foram feitas em função da temperatura e do campo de polarização das amostras. Das medidas de r13 e de medidas de CDET conclui-se que o primeiro pico de corrente é associado a desorientação dipolar do grupo ONL. A falta de familiaridade com o copolímero MMADR13 e a dificuldade de se obter medidas com boa reprodutibilidade tornou difícil a sua caracterização deixando ainda vários aspectos não bem compreendidos. / Polymeric materials with nonlinear optical properties are attracting attention because of the interest of its application to NLO devices. In this work the side-chain copolymer MMA-DR13 having methyl methacrylate monomer (MMA) and a monomer of methyl methacrylate attached to the disperse red 13 (MMA-DR13) was prepared. Since the optical nonlinear activity is related with dipolar electrical polarization the properties of MMA-DR13 copolymer was investigated by means of electric conduction measurements, thermally stimulated depolarization current (CDET) and electro-optical measurements. The dependence of the electro-optic coefficient, r13 on temperature and polarization field of samples were investigated. From the measurements it was found that the electric conduction on samples depends on the electrodes, voltage polarity and on measurement environment. Measurements of r13 and CDET allowed to conclude that the first peak of current is related to dipolar relaxation of the DR13 groups. The inexperience on handling the MMA-DR13 copolymer and the difficulty to obtain reproducible results impaired the characterization of the MMA-DR13 copolymer.

This thesis presents studies on a novel ‘meta-material’ as a potential candidate to replace the traditional Electro-Optic crystals (GaP, ZnTe) used in ultrashort bunch monitors for electron/positron accelerators. This study is aimed at showing the linear and non-linear optical properties of such materials, and creating a toolbox for both optical characterisation and manipulation of their properties using an ultra-short pulsed laser. The material studied throughout this thesis is a composite of silver nanoparticles (a “nanocomposite”) embedded within soda-lime glass. The Surface Plasmon Resonance (SPR) is a feature of these particles that is responsible for its unique optical properties. It is shown in this work how SPR is utilised for shape modification of silver nanoparticles with the use of a ps- pulsed laser with various laser beam polarisations. The impact of linear polarisation irradiation is investigated. It is found that multipulse irradiation has the effect of elongating nanoparticles to form prolate spheroids, which results in a dichroic effect on the composite as a whole, caused by the anisotropic SPR band shift. It is also shown that changing the laser polarisation from linear to radial and/or azimuthal changes the character of the reshaped nanoparticles. It was observed that a localised change of ellipsoid orientation is achieved, resulting in a non-directionally-dependent SPR band shift. Second Harmonic Generation (SHG) has been observed from reshaped nanoparticles embedded in soda-lime glass. A comparison of the effect was made between ps-pulsed reshaped, fs-pulsed reshaped and mechanically stretched samples containing silver nanoparticles. Multiphoton Absorption Induced Luminescence (MAIL) was observed along with the SHG and characterised for the various laser polarisation components. The dependence of the aforementioned effects on the elongated nanoparticle aspect ratio was shown to have a great impact. A novel method for reshaped nanoparticles characterisation is presented. It is based on the laser-induced SHG and MAIL signal and is proved to give a precise measurement of the nanoparticle shape and orientation. Frequency Resolved Optical Gating (FROG) measurement of a fs-pulse is measured with great accuracy, in the case where the BBO nonlinear crystal is replaced by the reshaped nanoparticle composite. This was demonstrated to be caused by the anisotropic SHG of the ellipsoidal nanoparticles. Preliminary THz based measurements were performed as a part of a feasibility study of the application of these composites in the EO-based detection of ultrashort electron bunches. Future work is suggested in order to achieve more efficient EO detection.

Materiais poliméricos podem exibir propriedades ópticas não lineares (ONL), o que motiva hoje em dia, muitas pesquisas para sua aplicação em dispositivos optoeletrônicos. Neste trabalho descreve-se a preparação do copolímero do tipo grupo lateral (\"side-chain\") formado pelos monômeros metacrilato de metila (MMA) e monômeros metacrilato de metila ligado a molécula disperso vermelho 13 (MMA-DR13). Como a atividade óptica não-linear de segunda ordem dos materiais poliméricos está diretamente ligada a sua polarização elétrica dipolar (alinhamento de dipolos), o presente trabalho investiga as propriedades do copolímero MMA-DR13 através de medidas de condução elétrica, correntes de despolarização estimuladas termicamente (CDET) e medidas eletroópticas. As medidas de condução elétricas feitas a diferentes temperaturas mostraram a ser dependentes do tipo substratos/eletrodos, da polaridade de tensão e atmosferas na qual foram realizadas as medidas. Nas medidas de CDET observou-se que aparecem mais de um pico de corrente em função da temperatura. As medidas do coeficiente eletroóptico r13 foram feitas em função da temperatura e do campo de polarização das amostras. Das medidas de r13 e de medidas de CDET conclui-se que o primeiro pico de corrente é associado a desorientação dipolar do grupo ONL. A falta de familiaridade com o copolímero MMADR13 e a dificuldade de se obter medidas com boa reprodutibilidade tornou difícil a sua caracterização deixando ainda vários aspectos não bem compreendidos. / Polymeric materials with nonlinear optical properties are attracting attention because of the interest of its application to NLO devices. In this work the side-chain copolymer MMA-DR13 having methyl methacrylate monomer (MMA) and a monomer of methyl methacrylate attached to the disperse red 13 (MMA-DR13) was prepared. Since the optical nonlinear activity is related with dipolar electrical polarization the properties of MMA-DR13 copolymer was investigated by means of electric conduction measurements, thermally stimulated depolarization current (CDET) and electro-optical measurements. The dependence of the electro-optic coefficient, r13 on temperature and polarization field of samples were investigated. From the measurements it was found that the electric conduction on samples depends on the electrodes, voltage polarity and on measurement environment. Measurements of r13 and CDET allowed to conclude that the first peak of current is related to dipolar relaxation of the DR13 groups. The inexperience on handling the MMA-DR13 copolymer and the difficulty to obtain reproducible results impaired the characterization of the MMA-DR13 copolymer.

No description available.

No description available.

Pour répondre aux questions que pose la faisabilité d’un dispositif de détection d’explosifsà l’aide de la technologie de spectroscopie térahertz, cette thèse a exploré troisaxes. Le premier a consisté à établir une base de données des signatures spectrales (indiceet absorption) d’une large gamme de matériaux d’intérêt pour ce type d’applications,à partir des données expérimentales que nous avons mesurées par spectroscopie dans ledomaine temporel. Nous avons identifié les matériaux montrant une signature spectralesignificative et nous avons aussi étudié l’effet des matériaux de dissimulation.Dans la seconde partie de ce travail, nous avons conçu et construit un banc de spectroscopieultra-large bande destiné à une meilleure identification spectrale des substances. Nousavons identifié les limites techniques de ce type de banc et donné les pistes pour atteindreles performances désirées.Ensuite, nous avons développé et validé un banc de spectroscopie en réflexion, de typegoniométrique, afin de détecter des signaux térahertz diffusés par des matériaux hétérogènes.Finalement, nous avons étudié les plasmons de surface dans le domaine térahertz, en vuede la détection de très faibles quantités de matière. / This PhD work was performed in view of using terahertz electromagnetic signals forthe detection and identification of dangerous and prohibited substances. In a first stage,a database of the terahertz properties (namely refractive index and absorption) of thesesubstances was created from the measurements we performed using terahertz time-domainspectroscopy. Then a large bandwidth terahertz time-domain set up has been built, togetherwith a goniometric-type set up that allows us recording signals scattered by roughor heterogeneous samples. Finally, we studied the excitation and propagation of surfaceplasmons in the terahertz domain, which may be used for the detection of small amountsof matter.

No description available.

<p>Electro-optic phase modulation can be used to generate high repetition rate optical frequency combs. The optical frequency comb (OFC) has garnered much attention upon its inception, acting as a crucial component in applications ranging from metrology and spectroscopy, to optical communications. Electro-optic frequency combs (EO combs) can be generated by concatenating an intensity modulator and phase modulator together. The first part of this work focuses on broadening the modest bandwidth inherent to the EO combs. This is achieved by propagation in a nonlinear medium, specifically propagation in a nonlinear optical loop mirror (NOLM). This allows for broadening the EO frequency comb spectrum to a bandwidth of 40 nm with a spectral power variation of < 10 dB. This spectrally broadened EO comb is then used in dual comb interferometry measurements to characterize the single soliton generated in an anomalous dispersion silicone-nitride microresonator. This measurement allows for rapid characterization with low average power. Finally, electro-optic phase modulation is used in a technique to prove frequency-bin entanglement. A quantum network based on optical fiber will require the ability to perform phase modulation independent of photon polarization due to propagation in optical fiber scrambling the polarization of input light. Commercially available phase modulators are inherently dependent on the polarization state of input light making them unsuited to be used in such a depolarized environment. This limitation is overcome by implementing a polarization diversity scheme to measure frequency-bin entanglement for arbitrary orientations of co- and cross- polarized frequency-bin entangled photon pairs.</p>

Cette thèse porte sur les différentes voies de fonctionnalisation et d'auto-organisation d'un système modèle dans le domaine de la matière condensée : le virus fd et ses mutants. Alors que son diagramme de phase cristal-liquide a été établi et sa correspondance qualitative avec les prédictions théoriques montrée, une des perspectives majeure consiste en son utilisation comme brique élémentaire dans la construction de nouveaux auto-assemblages. De telles avancées passent nécessairement par l'ajout de fonctions de manière régio-sélective sur le corps de la particule. Nous proposons dans ces travaux l'étude de plusieurs voies de fonctionnalisation menant à l'ajout d'espèces moléculaires ou macromoléculaires soit sur l'ensemble du virus ou bien uniquement à son extrémité.En réalisant le greffage de polymères thermosensibles, il est alors possible d'explorer les possibilités d'induire une transition de phase par variation du diamètre effectif du bâtonnet. En utilisant des diblocs d'élastine, ce principe est montré sur la transition entre le liquide isotrope et la phase nématique. L'utilisation de mutants particuliers, conçus par phage display, permet de s'intéresser alors uniquement à la fonctionnalisation de la protéine p3 située à une des extrémités du phage. L'ajout de chromophores permet alors une visualisation unique de la phase smectique et de ses défauts et crée également un effet patchy perturbant le diagramme de phase cristal-liquide. La biotine quant à elle permet la création d'auto-assemblages du fait de son interaction spécifique avec les dérivés d'avidine et un tel système est alors comparé avec un mutant dont l'ADN modifié permet l'expression directe d'une étiquette biologique complémentaire de la streptavidine. Les résultats prometteurs obtenus sont également complétés par une étude encourageante pour l'utilisation des systèmes cristal-liquides colloïdaux dans le domaine de l'électro-optique. / This thesis deals with the different paths of functionalization and self-organization of a model system of colloidal rod-like particles: the fd virus and its mutants. While its liquid-crystalline phase diagram is well established and proven to be in qualitative agreement with theory and numerical simulations, one of the most trending perspectives is its use as building-block in new self-assemblies. For such purposes, it is mandatory to add functions regio-specifically on the particle. We show in this work the study of several ways of functionalization leading to the grafting of molecular or macromolecular compounds onto the whole virus or only onto its tip.When grafting thermoresponsive polymers, we can then explore the possibilities to induce phase transitions by a variation of the effective diameter of the rod. Using diblocs of elastin-like peptides, this principle is shown to work on the isotropic-to-nematic phase transition. The use of particular mutants, engineered by phage display, allows us to functionalize only the tip of the virus. The addition of dyes provides unique features on the smectic phase and its defects and creates a patchy effect which is modifying the liquid-crystalline phase diagram. The functionalization with biotin leads towards the creation of new self-assemblies thanks to its specific interaction with avidine and such a system is then compared with a mutant displaying a biological tag interacting with streptavidin. The results obtained are promising and are completed by a whole study of the use of colloidal liquid-crystalline system in electro-optics.