I developed a high power blue laser for use in scientific and technical applications (eg. precision spectroscopy, semiconductor inspection, flow cytometry, etc). It is linearly polarized, single longitudinal and single transverse mode, and a convenient fiber coupled continuous wave (cw) laser source. My technique employs external cavity frequency doubling and provides better power and beam quality than commercially available blue diode lasers. I use a fiber Bragg grating (FBG) stabilized infrared (IR) semiconductor laser source with a polarization maintaining (PM) fiber coupled output. Using a custom made optical and mechanical design this output is coupled with a mode matching efficiency of 96% into the doubling cavity. With this carefully designed and optimized cavity, measurements were carried out at various fundamental input powers. A net efficie ncy of 81 % with an output power of 680 mW at 486 nm was obtained using 840 mW of IR input. Also I report an 87.5 % net efficiency in coupling of blue light from servo locked cavity into a single mode PM fiber. Thus I have demonstrated a total fiber to fiber efficiency of 71% can be achieved in our approach using periodically poled potassium titanyl phosphate (PPKTP). To obtain these results, all losses in the system were carefully studied and minimized.

Nous avons développé une nouvelle méthode de microscopie par effet électro-optique linéaire (effet Pockels), dite PLEOM, permettant de cartographier la susceptibilité du deuxième ordre Chi(2) d'un matériau non-centrosymétrique [1, 2]. Cette méthode est complémentaire de la microscopie de génération de seconde harmonique, et s’en distingue par différents aspects physiques et pratiques. Grâce à une détection interférométrique stabilisée, le retard de phase provoqué par une variation d'indice locale du matériau non-linéaire sous l'effet d'un champ électrique est détecté à 10-6 radians près, ouvrant la voie à l'imagerie d'échantillons biologiques ou au suivi du mouvement de nano-sondes [3]. PLEOM apporte un type de données nouveau, la "réponse en phase" du matériau, porteuse d'information physiques plus difficilement accessibles en microscopie biphotonique.Ce manuscrit décrit de nouveaux domaines de développement et d’application de PLEOM, qui a évolué vers une plateforme aux applications variées et multi-échelles, allant du nanométrique au millimétrique.Nous avons tout d’abord montré comment déterminer le vecteur de polarisation attaché à des nano-cristaux ferroélectriques uniques, en vue de leur utilisation comme nano-sondes. Cette nouvelle méthode permet, à notre connaissance de façon unique, de distinguer deux nano-cristaux mono-domaines d'orientations exactement opposées, dont les réponses en SHG ne peuvent pas être distinguées. Une image de phase électro-optique, combinée à un diagramme de polarisation, donne accès à l'orientation vectorielle d'un nano-cristal orienté aléatoirement dans le référentiel du laboratoire. Un verrou est ainsi levé pour des applications comme l'imagerie de nano-domaines ferroélectriques, celle de potentiels électrochimiques membranaires, où l'étude de la dynamique de rotation de molécules. Deux spécificités remarquables de PLEOM en font une méthode d'avenir : la faible intensité de pompage qui assure une bien meilleure biocompatibilité ainsi que la simplicité de la source laser continue utilisée.Nous avons ainsi pu utiliser PLEOM pour caractériser les domaines ferroélectriques d'un cristal de KTiOPO4 périodiquement réorienté en vue d’un quasi-accord de phase, ainsi que ceux d'un cristal bidimensionnel quasi-périodique de LiNbO3. Un retournement clair de la phase de 180 degree est observé au travers des parois de domaines, dont les coefficients électro-optiques apparaissent opposés dans le référentiel du laboratoire. PLEOM se présente ainsi comme un outil de caractérisation non destructif des propriétés de ces cristaux artificiels dont les motifs et les défauts (tels qu'une orientation localement incomplète) ont été caractérisés spatialement, et permet de mesurer localement leurs propriétés non-linéaires, dont le caractère tensoriel permet d’aller au-delà des informations acquises en microscopie classique.En outre, nous avons fait la preuve de principe d'une nouvelle expérience biomimétique, visant à étudier les potentiels membranaires cellulaires, en utilisant PLEOM sur des membranes phospholipidiques créées sur puce micro-fluidique et dopées en colorants. / Complementing Second-Harmonic Generation (SHG) microscopy, a new home-made nonlinear microscope named Pockels Linear Electro-Optical Microscopy (PLEOM) based on the linear electrooptic (Pockels) effect, has been developed and used to map the second-order susceptibility Chi(2) of non-centrosymmetric materials with high sensitivity due to a stabilized interferometric homodyne detection scheme [1, 2]. This enables PLEOM to detect the electrooptic phase retardation of light resulting from the variation of the refractive index of nonlinear materials down to 10-6 radian and to investigate nonlinear materials at the nano-scale [3] towards applications in imaging of biological samples and tracking of labels therein. With PLEOM, a new imaging method allows to access, besides the aplitude, the no less crucial phase response, which is not readily amenable to classical SHG microscopy. In the frame of this dissertation, we have further extended the range of applications of PLEOM to investigate nonlinear materials and structures from nano- to millimeter-scale.Firstly, we have proposed and demonstrated a new approach towards the full vector determination of the spontaneous polarization of single ferroelectric nano-crystals used as SHG nano-probes. This method allows to remove the ambiguity inherent to earlier polarization-resolved SHG microscopy experiments, and has permitted full determination of the orientation of single domain ferroelectric nano-crystals. The electrooptic phase response obtained in the form of phase images and polarization diagrams yields the full orientation in the laboratory frame of randomly dispersed single nano-crystals, together with their electric polarization dipole. The complete vector determination of the dipole orientation is a prerequisite to important applications including ferroelectric nano-domain orientation, membrane potential imaging and rotation dynamics of single biomolecules, especially by using a new low-cost non-invasive imaging method with a low intensity illumination beam.The ferroelectric domain pattern of periodically poled KTiOPO4 and of a two-dimensional decagonal quasi-periodic LiNbO3 nonlinear crystal was determined by local measurement of their electro-optically induced phase retardation. Owing to the sign reversal of the electrooptic coefficients upon domain inversion, a 180 degree (pi) phase shift is observed across domain barriers between domains with opposed orientations. PLEOM allows to reveal the nonlinear and electrooptic spatially modulated patterns in ferroelectric crystals in a non-destructive manner and to determine their poling period, duty cycle and short-range order as well as to detect local defects in the domain structure, such due to incomplete poling.In addition, we have also proposed and demonstrated a new method, based on the voltage dependence of the electrooptic dephasing, to mimic the membrane potential in cells, working at this stage on nonlinear dye containing phospholipidic membranes, grown in a microfluidic set-up.

No description available.

<p> In this work, tunable Mid-Infrared (IR) light sources based on quasi-phase matched (QPM) difference frequency generation (DFG) by periodically poled lithium niobate (PPLN) crystals are studied. The theory of DFG and the characteristics of lithium niobate crystals are described and analyzed. Characteristics of the wavelength tuning of QPM DFG by PPLN crystals are studied. In order to analyze in detail, simulation and experimental data of the widely tunable mid-IR laser source around 2 1- μm to 5 1- μm wavelength are presented. The simulations of DFG process by PPLN are conducted based on the nonlinear optics reported. In the experiment, a 1.064 μm Nd:YAG laser and a tunable Ti:sapphire laser are employed as the signal and pump lasers, respectively. Based on the studies of the wavelength tuning characteristics at different temperatures, an optimization procedure to achieve a maximum wavelength tuning range is proposed. The potential applications in gas detection of the mid-IR source are also described briefly. Recommendation for future works and potential applications of the PPLN DFG based mid-IR lasers are discussed. </p> / Thesis / Master of Applied Science (MASc)

La miniaturisation est l’objectif actuel de tous les fabricants de composants radio-fréquence depuis plusieursdécennies. Si les composants actifs pour la microélectronique sont fondés sur la structuration de plaquesde silicium, les composants passifs reposent sur l’utilisation de cristaux tels que le quartz ou le niobate delithium. Ce dernier est particulièrement utilisé quand il s’agit de générer et exploiter des ondes élastiques, ainsique pour le guidage de faisceaux lumineux afin de réaliser des filtres ou des capteurs sensibles à différentsparamètres environnementaux. L’amélioration du guidage de ces ondes permet un gain en consommation et encompacité des dispositifs mais nécessite une structuration de la matière souvent tridimensionnelle. Cette étapetechnologique clé est industriellement mature pour la mise en forme du silicium, mais s’avère di_cilementtransposable à des matériaux tels que le quartz ou le niobate de lithium. Les travaux présentés dans cemanuscrit visent à réaliser des structures tridimensionnelles à hauts facteurs de forme dans des matériauxmonocristallins à l’aide d’une scie circulaire de précision. Des structures utilisant l’inversion périodique dedomaine ferroélectrique seront réalisées afin de les utiliser pour y guider des ondes élastiques possédant descouplages électromécaniques particulièrement élevées. Le guidage d’ondes optiques par le biais de ces mêmesstructures permet une amélioration du confinement par rapport aux systèmes de guidage massifs classiquescouramment utilisés pour la réalisation de filtre ou de modulateur électro-optiques. En utilisant conjointementle guidage d’ondes optiques et les domaines ferroélectriques alternés, les structures ainsi découpées permettentl’apparition de phénomènes optiques non-linéaires exaltés par l’amélioration du confinement. Ces structuresont ainsi montré leur intérêt dans plusieurs domaines de la physique avec un champ applicatif particulièrementvaste / Over the past decades, minutiarization and compacity have become a focus subject for companies specialisedin the manufacturing of radio-frequency components. Active components are typically manuafctured onsilicon wafers with well-known structuring methods. Passive ones are often manufactured on single cristalsuch as Quartz or Lithium Niobate, especially for acoustic wave generation or lightwave guiding. Theguiding of optical or acoustical waves leads to the manufacturing of sensors or filters which can be usedfor telecommunications or for the industry. Improvement in waveguiding allows for less power-consuming andmore compact devices but a 3D-structuring is usually required. This technology readness is high leveled forsilicon structuring but not for single crystals such as Lithium Niobate. This work presents the development andthe manufacturing of high aspect ratio three-dimensionnal structures in single-crystals using precise sawing.These structures show an optical waveguiding capability which allow the improvements of electro-opticmodulators or filters. Combined with a periodic reversing of Lithium Niobate polarization, these structuresallows for bulk acoustic wave generation leading to high electromechanical coupling and equivalent phasevelocity resonant modes. In non-linear optic field, this kind of structures lead to the improvement of secondharmonic generation e_ciency by reducing the cross section of waveguide. The manufactured devices in theframework of this project can actuelly be used in several domains of physic.

¡@¡@We integrated the laser-heated pedestal growth (LHPG) system with accurately controlled electrodes to build up our in situ poling system. The ZnO and MgO doped periodically poled lithium niobate crystal fiber were fabricated with the poling system. This poling system has the advantage of convenience and fast growth, but the ¡§screen effect¡¨ caused by free charges which exist near the molten zone must be eliminated. The micro swing resulted from the electric force is a feasible solution, because it can disarrange the free charges and reduce the ¡§screen effect¡¨. However, without excellently controlled micro swing, the uniformity of the poled domain pitch will loose and the conversion efficiency can not be improved. After analysis of the measured current data, the approximate system current model was presented and the proportional dependence between system current and micro swing was verified. Thus the system current was applied as the micro swing feedback signal, with that the variation of the micro swing was reduced from 25% to 15%. The stability of CO2 laser power is also a dominant factor to determine the quality of poled crystal fiber. The variation of the CO2 laser power was controlled within 1%. All the complicated works and precise control during the crystal fiber growth were accomplished with the LabVIEW program. ¡@¡@A novel and simple self-cascaded SHG + SFG scheme is presented for the generation of tunable blue/green light using ZnO doped periodically poled lithium niobate crystal fiber (PPLNCF) with a single designed pitch. A PPLNCF with a uniform period of 15.45£gm, the maximum conversion efficiency for the second harmonic generation and the cascaded SHG + SFG blue light can reach up to -9.2 dB and -31.9 dB, respectively. The 3 dB bandwidth of the tunable blue light is 3 nm (475-478 nm). In order to expand the tuning bandwidth range, a QPM gradient periodical structure was designed and can provide a 3 dB bandwidth of 65 nm for the tunable blue/green light output by simulation. We have successfully grown a crystal fiber with the domain pitch of 18.9 £gm for the C-band wavelength converter. The crystal length is 1.8 mm, the effective nonlinear coefficient of the lithium niobate crystal fiber is 18.2 pm/V that equals 0.53¡Ñdideal (34.4 pm/V). The conversion efficiency for converting the CW laser in C-band is about -59.3 dB.

No description available.

[pt] É possível criar uma não-linearidade de segunda ordem em amostras de sílica a partir do processo de polarização. Essas amostras vítreas com o X(2) induzido potencialmente podem ser utilizadas na fabricação de componentes como moduladores ópticos e dobradores de freqüência. O processo de polarização eletrotérmica utiliza alta tensão e alta temperatura e forma uma região de depleção de íons (camada de depleção) onde um campo elétrico intenso é gravado de forma permanente dentro da amostra. Neste trabalho, foram utilizadas diferentes técnicas de caracterização para medir a extensão dessa camada e os resultados foram comparados. As técnicas escolhidas foram: Ataque Químico Interferométrico (com ácido fluorídrico), Maker Fringe, Microscopia Óptica e de Força Atômica e Ataque Interferométrico com Medida de Segundo Harmônico em Tempo Real. Além disso, foram feitos alguns estudos paralelos visando à otimização e a reprodutibilidade do processo de polarização. Foram realizadas dessa forma análises sobre o material dos eletrodos utilizados e sobre a influência da condição inicial da superfície da amostra antes da polarização. / [en] It is possible to create a second order non linearity in silica samples with the poling process. The glass samples with an induced X(2) have a potential application on the fabrication of optical devices such as modulators and frequency converters. In the electrothermal poling process, high voltage and high temperature are applied to the samples forming an ion depleted region (depletion layer), where an intense electric field is permanently recorded. In this work, several characterization techniques have been utilized to measure the width of the depletion layer and compared the obtained results. The chosen techniques were: Interferometric Etching, Maker Fringe, Optical and Atomic Force Microscopy and the Interferometric Etching with Real Time Second Harmonic Measurement. In addition to this, we performed other studies aiming the optimization and reproducibility of the poling process. In this way, we analyzed the material used for the electrodes and the influence of the initial condition of the sample surface before poling.

Le but de ce travail de thèse est de contrôler via un traitement de polarisation les propriétés physico-chimiques de surface des verres. Pour cela, l'implémentation d'une charge d'espace au sein de différents verres silicates et borosilicates a été caractérisée. Ces études comparatives ont montré que la déplétion des cations de l’anode vers la cathode induit l’apparition d’un champ électrique et des modifications structurales localisées. De plus, nous avons démontré que la formation d’un plasma entre l’anode et le verre pouvait être à l’origine de phénomènes d'échanges ioniques conduisant notamment à la formation d’entités azotées NO2/N2O4 piégées dans le verre. Par la suite, une étude des propriétés physico-chimiques des surfaces polarisées a été conduite. Les résultats préliminaires obtenus concernent l'influence de la charge d'espace sur (i) la mouillabilité, (ii) la chimie de surface et (iii) les réponses optiques de molécules adsorbées. / The purpose of this work is to control physicochemical properties of glasses surfaces using a thermal polarization treatment. For this, the implementation of a space charge layer has been characterized for various silicates and borosilicates glasses. These comparative studies have shown that cations depletion from anode toward cathode induces both an electric field and structural local changes. To go further, we demonstrated that there is a plasma formation between anode and glass surfaces which could be the cause of ionic exchange phenomena leading to the formation of nitrogen NO2/N2O4 entities entrapped inside glass network. Subsequently, physicochemical properties studies of polarized surfaces were performed. Preliminary results concerning the space charge influence on (i) surface wettability, (ii) surface chemistry and (iii) optical responses of adsorbed molecules on poled glass surface have been obtained.

Le premier volet de cette thèse est consacré à la modélisation des phénomènes de transport dans le LN. Partant d'une analyse critique des modèles de bande usuels, nous montrons leur inadéquation dans le cas du LN et nous proposons un modèle de saut basé sur la théorie des petits polarons. Nous étudions d'abord par simulation Monte-Carlo la décroissance d'une population de polarons liés NbLi4+ relaxant vers des pièges profonds FeLi3+. Nous montrons que les pièges FeLi3+ ont des rayons effectifs particulièrement grands, rayons qui augmentent encore à température décroissante, et limitent considérablement les longueurs de diffusion des polarons. Les résultats de simulations sont ensuite confrontés aux résultats expérimentaux obtenus par différentes techniques ; Absorption photo-induite, Raman, Enregistrement holographique et Pompe-sonde. Le deuxième volet de cette thèse est consacré aux applications électro-optiques dans le LN périodiquement polarisé (PPLN). Sous l’effet d’une tension électrique, l’indice de réfraction du PPLN est périodiquement diminué et augmenté, formant ainsi un réseau d’indice activable électriquement. Un premier composant utilisant l’effet électro-optique dans du PPLN a été développé et démontré expérimentalement. Dans ce composant, la lumière est défléchie sous l’effet de la tension électrique par le réseau d’indice. Ce déflecteur de Bragg atteint une efficacité de diffraction proche de 100% avec une faible tension de commande de l’ordre de 5 V. Un deuxième composant a également été proposé, où la lumière se propage perpendiculairement aux parois de domaines du PPLN. Dans cette configuration un réflecteur de Bragg électro-optique peut être réalisé / The first part of this thesis is devoted to the modeling of transport phenomena in the LN. From a critical analysis of the usual band models, we show their inadequacy in the case of LN and we propose a hopping model based on the theory of small polarons. We first study by Monte-Carlo simulation the population decay of bound polarons NbLi4+ in deep traps FeLi3+. We show that the traps (FeLi3+) have particularly large effective radii, which increase further at decreasing temperature, and considerably limit the diffusion lengths of the polarons. The results of simulations are then compared with experimental results obtained by different techniques; Light-induced absorption, Raman, Holographic storage and Pump-Probe. The second part of this thesis is devoted to electro-optical applications in the periodically poled LN (PPLN). Under the effect of an electrical voltage, the refractive index of the PPLN is periodically decreased and increased, thus forming an electrically activatable index grating. A first component using the electro-optical effect in PPLN has been developed and demonstrated experimentally. In this component, the light is deflected under the effect of the electrical voltage by the index grating. This Bragg deflector achieves a diffraction efficiency of close to 100% with a low drive voltage of the order of 5 V. A second component has also been proposed, where light propagates perpendicularly to the domain walls of the PPLN. In this configuration an electro-optic Bragg reflector can be realized