Transition metal compounds, especially the oxides, containing dn (0 ≤ n ≤ 10) electronic configuration, constitute the backbone of solid state/materials chemistry aimed at realization of novel materials properties of technological importance. Some of the significant materials properties of current interest are spin-polarized metallic ferromagnetism, negative thermal expansion, second harmonic nonlinear optical (NLO) susceptibility, fast ionic and mixed electronic/ionic conductivity for application in solid state batteries, and last but not the least, high-temperature superconductivity. Typical examples for each one of these properties could be found among transition metal oxides. Thus, alkaline-earth metal (A) substituted rare-earth (Ln) manganites, Lnı.xAxMnΟ3, are currently important examples for spin-polarized magnetotransport, ZrV2O7 and ZrW2O8 for negative thermal expansion coefficient, KTiOPO4 and LiNbO3 for second harmonic NLO susceptibility, (Li, La) TiO3 and LiMn2O4 for fast-ionic and mixed electronic/ionic conductivity respectively, and the whole host of cuprates typified by YBa2Cu3O7 for high Tc superconductivity. Solid state chemists constantly endeavour to obtain structure-property relations of solids so as to be able to design better materials towards desired properties. Synthesis coupled with characterization of structure and measurement of relevant properties is a common strategy that chemists adopt for this task. The work described in this thesis is based on such a broad-based chemists' approach towards understanding and realization of novel materials properties among the family of metal oxides. A search for metallic ferro/ferrimagnetism among the transition metal perovskite oxides, metallicity and possibility of superconductivity among transition-metal substituted cuprates and second order NLO susceptibility among metal oxides containing d° cations such as Ti(IV), V(V) and Nb(V) - constitute the main focus of the present thesis. New synthetic strategies that combine the conventional ceramic approach with the chemistry-based 'soft1 methods have been employed wherever possible to prepare the materials. The structures and electronic properties of the new materials have been probed by state-of-the art techniques that include powder X-ray diffraction (XRD) together with Rietveld refinement, electron diffraction, thermogravimetry, measurement of magnetic susceptibility (including magnetoresistance), Mossbauer spectroscopy and SHG response (towards 1064 nm laser radiation), besides conventional analytical techniques for determination of chemical compositions. Some of the highlights of the present thesis are: (i) synthesis of new mixed valent [Mn(III)/Mn(IV)] perovskite-type manganites, ALaMn2O6-y (A = K, Rb) and ALaBMn3O9_y (A = Na, K; B = Ca, Sr) that exhibit ferromagnetism and magnetoresistance; (ii) investigation of a variety of ferrimagnetic double-perovskites that include ALaMnRuO6 (A = Ca, Sr, Ba) and ALaFeVO6 (A = Ca, Sr) and A2FeReO6 (A = Ca, Sr, Ba) providing new insights into the occurrence of metallic and nonmetallic ferrimagnetic behaviour among this family of oxides; (iii) synthesis of new K2NiF4-type oxides, La2-2xSr2XCui.xMxO4 (M = Ti, Mn, Fe, Ru) and investigation of Cu-O-M interaction in two dimension and (iv) identification of the structural rnotif(s) that gives rise to efficient second order NLO optical (SHG) response among d° oxides containing Ti(IV), V(V), Nb(V) etc., and synthesis of a new SHG material, Ba2-xVOSi2O7 having the fresnoite structure. The thesis consists of five chapters and an appendix, describing the results of the investigations carried out by the candidate. A brief introduction to transition metaloxides, perovskite oxides in particular, is presented in Chapter 1. Attention is focused on the structure and properties of these materials. Chapter 2 describes the synthesis and investigation of two series of anion-deficient perovskite oxides, ALaMn2O6-y (A = K, Rb, Cs) and ALaBMn3O9_y (A = Na, K; B = Ca, Sr). ALaMn2O6-y (A = K, Rb, Cs) series of oxides adopt 2 ap x 2 ap superstructure for K and Rb phases and √2 av x √2 ap x 2 ap superstructure (ap = perovskite subcell) for the Cs phase. Among ALaBMn3O9-y phases, the A = Na members adopt a new kind of perovskite superstructure, ap x 3 ap, while the A = K phases do not reveal an obvious superstructure of the perovskite. All these oxides are ferromagnetic (Tc ~ 260-325 K) and metallic exhibiting a giant magnetoresistance behaviour similar to alkaline earth metal substituted lanthanum manganites, Lai_xAxMnO3. However, unlike the latter, the resistivity peak temperature Tp for all the anion-deficient manganites is significantly lower than Tc. In Chapter 3, we have investigated structure and electronic properties of double-perovskite oxides, A2FeReO6 (A = Ca, Sr and Ba). The A = Sr, Ba phases are cubic (Fm3m) and metallic, while the A = Ca phase is monoclinic (P2yn) and nonmetallic. All the three oxides are ferrimagnetic with Tcs 315-385 K as reported earlier. A = Sr, Ba phases show a negative magnetoresistance (MR) (10-25 % at 5 T), while the Ca member does not show an MR effect. 57Fe Mossbauer spectroscopy shows that iron is present in the high-spin Fe3+ (S = 5/2) state in Ca compound, while it occurs in an intermediate state between high-spin Fe2+ and Fe3+ in the Ba compound. Monoclinic distortion and high covalency of Ca-O bonds appear to freeze the oxidation states at Fe+3/Re5+ in Ca2FeRe O6, while the symmetric structure and ionic Ba-O bonds render the FeReO6 array highly covalent and Ba2FeReO6 metallic. Mossbauer data for Sr2FeReO6 shows that the valence state of iron in this compound is intermediate between that in Ba and Ca compounds. It is likely that Sr2FeReO6 which lies at the boundary between metallic and insulating states is metastable, phase-seperating into a percolating mixture of different electronic states at the microscopic level. In an effort to understand the occurrence of metallicity and ferrimagnetism among double perovskites, we have synthesized several new members : ALaMnFeO6 (A = Ca, Sr, Ba), ALaMnRuO6 (A = Ca, Sr, Ba) and ALaVFeO6 (A = Ca, Sr) (Chapter 3). Electron diffraction reveals an ordering of Mn and Ru in ALaMnRuO6 showing a doubling of the primitive cubic perovskite cell, while ALaVFeO6 do not show an ordering. ALaMnRuOs are ferrimagnetic (Tcs ~ 200-250 K) semiconductors, but ALaVFeO6 oxides do not show a long range magnetic ordering . The present work together with the previous work on double perovskites shows that only a very few of them exhibit both metallicity and ferrimagnetism, although several of them are ferrimagnetic. For example, among the series Ba2MReO6 (M = Mn, Fe, Co, Ni), only the M = Fe oxide is both metallic and ferrimagnetic, while M = Mn and Ni oxides are ferrimagnetic semiconductors. Similarly, A2CrMoO6 (A = Ca, Sr), A2CrRe06 (A = Ca, Sr), and ALaMnRuO6 (A = Ca, Sr, Ba) are all ferrimagnetic but not metallic. While ferrimagnetism of double perovskites arise from an antiferromagnetic coupling of B and B' spins through the B-O-B' bridges, the occurrence of metallicity seems to require precise matching of the energies of d-states of B and B' cations and a high covalency in the BB'O6 array that allows a facile electron-transfer between B and B', Bn++B’m+↔B(n+1)++B’(m-1)+ without an energy cost, just as occurs in ReO3 and other metallic ABO3 perovskites. In an effort to understand the Cu-O-M (M = Ti, Mn, Fe, Ru) electronic interaction in two dimension, we have investigated K2N1F4 oxides of the general formula La2-2xSr2XCui.xMxO4 (M = Ti, Mn, Fe or Ru). These investigations are described in Chapter 4. For M = Ti, only the x = 0.5 member could be prepared, while for M = Mn and Fe, the composition range is 0 < x < 1.0, and for M = Ru, the composition range is 0 < x ≤ 0.5. There is no evidence for ordering of Cu(II) and M(IV) in the x = 0.5 members. While the members of the M = Ti, Mn and Ru series are semiconducting/insulating, the members of the M = Fe series are metallic, showing a broad metal-semiconductor transition around 100 K for 0 < x ≤ 0.15 that is possibly related to a Cu(II)-O-Fe(IV) < > Cu(III)-O-Fe(III) valence degeneracy. Increasing the strontium content at the expense of lanthanum in La2-2xSr2XCui.xFexO4 for x ≤ 0.20 renders the samples metallic but not superconducting. In a search for inorganic oxide materials showing second order nonlinear optical (NLO) susceptibility, we have investigated several borates, silicates and phosphates containing /ram-connected MO6 octahedral chains or MO5 square-pyramids, where M = d°: Ti(IV), Nb(V) or Ta(V). Our investigations, which are described in Chapter 5, have identified two new NLO structures: batisite, Na2Ba(TiO)2Si4O12, containing trans-connectd TiO6 octahedral chains, and fresnoite, Ba2TiOSi2O7, containing square-pyramidal T1O5. Investigation of two other materials containing square-pyramidal TiO5, viz., Cs2TiOP2O7 and Na4Ti2Si8O22. 4H2O, revealed that isolated TiO5 square-pyramids alone do not cause a second harmonic generation (SHG) response; rather, the orientation of T1O5 units to produce -Ti-O-Ti-O- chains with alternating long and short Ti-0 distances in the fresnoite structure is most likely the origin of a strong SHG response in fresnoite. Indeed, we have been able to prepare a new fresnoite type oxide, Ba2.xVOSi2O7 (x ~ 0.5) that shows a strong SHG response, confirming this hypothesis. In the Appendix, we have described three synthetic strategies that enabled us to prepare magnetic and NLO materials. We have shown that the reaction CrO3 + 2 NH4X > CrO2 + 2 NH3 + H2O + X2 (X = Br, I), which occurs quantitatively at 120-150 °C, provides a convenient method for the synthesis of CrO2. Unlike conventional methods, the method described here does not require the use of high pressure for the synthesis of this technologically important material. For the synthesis of magnetic double perovskites, we have developed a method that involves reaction of basic alkali metal carbonates with the acidic oxides (e.g. Re2O7) first, followed by reaction of this precursor oxide with the required transition metal/transition metal oxide (e.g. Fe/Fe2O3). By this method we have successfully prepared single-phase perovskite oxides, A2FeReO6, ACrMoO6 and ALaFeVO6. We have prepared the new NLO material Ba2_xV0Si207 from Ba2VOSi2O7 by a soft chemical redox reaction involving the oxidation of V(IV) to V(V) using Br2 in CH3CN/CHCI3. Ba2V0Si207 + 1/2 Br2 > Bai.5V0Si207 + 1/2 BaBr2. The work presented in this thesis was carried out by the candidate as part of the Ph.D. training programme. He hopes that the studies reported here will constitute a worthwhile contribution to the solid state chemistry of transition metal oxides and related materials.

Le développement des technologies optiques dans le domaine de la communication engendre un intérêt pour les matériaux présentant des propriétés non linéaires. Le matériau idéal doit combiner un coefficient non linéaire élevé, de bonnes propriétés optiques et un faible coût de fabrication. Les matériaux vitreux restent de bons candidats pour ce type d’application. La polarisation thermique permet de générer ce genre de propriétés dans les verres. En effet, à des températures de l’ordre de 300°C, l’application d’un champ électrique provoque la migration d’ions mobiles dans le matériau depuis l’anode vers la cathode. Une zone de déplétion en surface est ainsi créée donnant naissance à un champ électrique enterré. En combinant une technique de dépôt métallique, une irradiation laser et l’application d’un champ électrique (poling), il devient possible de réaliser des architectures complexes de migration et d’obtenir ainsi des propriétés optiques non linéaires structurées. / Optical technologies development for communication has triggered a real interest about materials with nonlinear properties. The ideal material should combine a high nonlinear coefficient, good optical properties and a low production cost. Glasses remain very good materials for this kind of applications.Thermal poling is now well known for breaking glasses natural centro-symmetry and inducing second order nonlinearities. Indeed, at temperatures close to 300°C, the application of an electric field induces mobile ions migration from the anode to the cathode.In that case, the space charge created during the poling process generates an efficient macroscopic electrostatic field trapped under the anodic surface of the glass.The combination of silver deposition, femtosecond laser irradiation and thermal poling has been successfully used to realize a complex architecture of ionic migration leading to structuring of second order nonlinear properties at the microscopic scale.

L’objectif de cette thèse est l’élaboration de sondes organiques pour la microscopie optique non-linéaire par fluorescence excitée à deux photons (F2P) et génération de seconde harmonique (GSH). Dans une première partie, cette thèse décrit la synthèse de sondes pour l’imagerie de potentiels de membrane par GSH, comportant un ou plusieurs motifs sucres ainsi que leurs caractérisations spectroscopiques. Les premiers essais en imagerie biologique ont permis de démontrer une bonne affinité des sondes sucres pour la membrane cellulaire et un signal de GSH sur cellule neuronale a pu être observé sur une période de temps allant jusqu'à près de trois heures. La seconde approche a consisté à synthétiser et étudier des chromophores possédant des propriétés de fluorescence à l’état solide pour des applications dans la synthèse de nanoparticules fluorescentes pour l’imagerie biologique. 18 des 21 composés synthétisés ont pu être cristallisés et leur structure résolue par diffraction des rayons X et les propriétés spectroscopique en solution et à l’état solide ont été réalisées. Cette étude a permis de montrer que l’arrangement des molécules les unes par rapport aux autres avait une grande influence sur la fluorescence à l’état solide et donc que les substituants avaient une grande importance. Enfin, cette partie se termine sur les premiers essais effectués pour synthétiser des nanoparticules fluorescentes. / The objective of this thesis is the design of new organic probes for nonlinear optical microscopy by two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). In the first part, we describe the synthesis of probes for voltage sensitive imaging by SHG, bearing one or more sugar units and their spectroscopic characterization. The first biological imaging tests have shown good affinity of the probes to the cell membrane and the SHG signal of neuronal cell was observed over a period of nearly three hours. The second part comprises the synthesis and the study of chromophores with solid state fluorescence properties for use in fluorescent nanoparticles for biological imaging. 18 of the 21 compounds synthesized have been crystallized, their crystal structures determined by X-ray diffraction and their spectroscopic properties studied in solution and in the solid state. These studies showed that the arrangement of molecules relative to each had a great influence on the solid state fluorescence and therefore that the substitution was very important. The chapter ends with the first tests of fluorescent nanoparticles synthesis.

L'objet de cette thèse porte sur la conception et la réalisation de deux sources laser non linéaires accordables dans les domaines IR et UV, pour le raccordement de la sensibilité spectrale des détecteurs au moyen du radiomètre cryogénique du laboratoire commun de métrologie (LCM). La source IR est un oscillateur paramétrique optique (OPO) résonant sur les ondes pompe et signal (PRSRO), utilisant un cristal de niobate de lithium à inversion de domaines de polarisation dopé par 5% d'oxyde de magnésium (ppMgCLN). Pompé par un laser Ti:Al2O3 en anneau mono-fréquence et accordable, délivrant 500 mW de puissance utile autour de 795 nm, l'OPO possède un seuil d'oscillation de 110 mW. Une couverture spectrale continue entre 1 µm et 3.5 µm a été obtenue, avec des puissances de l'ordre du mW pour l'onde signal (1 µm à 1.5 µm) et des puissances comprises entre $20$ à $50$ mW pour l'onde complémentaire couvrant un octave de longueur d'onde IR entre 1.7 µm et 3.5 µm. La source UV est obtenue par doublage de fréquence en cavité externe du laser Ti:Al2O3, dans un cristal de triborate de lithium (LiB3O5). Un accord de phase en température à angle d'accord de phase fixé permet l'obtention d'une couverture spectrale comprise entre 390 nm et 405 nm. L'asservissement de la cavité de doublage sur la fréquence du laser Ti:Al2O3 par la méthode de Pound-Drever-Hall, ainsi qu'une adaptation de mode optimale, permet d'obtenir une puissance de 5.64 mW à 400 nm à partir de 480 mW de puissance fondamentale. / The work presented in this PhD dissertation details the strategy adopted to build two non-linear laser sources that are widely in the mid-infrared and blue-UV spectral ranges. These laser sources are needed for the traceability to SI units of coherent light irradiance measurements using a cryogenic radiometer of the using cryogenic radiometer of the Laboratoire commun de métrologie (LCM) .The infrared laser source is an optical parametric oscillator (OPO) resonating on the pump and signal wavelengths (PRSRO) and employing a periodically poled Lithium Niobate non-linear crystal doped with 5% magnesium oxide (ppMgCLN). The PRSRO is pumped by a single-frequency tunable bow-tie ring cavity Titanium-Sapphire laser (Ti:Al2O3) delivering 500 mW output power at 795 nm wavelength, , resulting in a power oscillation threshold of 110 mW. The PRSRO emission could continuously cover the spectral range from 1 µm to 3.5 µm. The level of output power achieved is of the order of 1 mW for the signal wave (1 µm to 1.5 µm) and between 20 mW and 50 mW for idler wave spanning an octave wavelength range (1.7 µm to 3.5 µm).The UV source based on the second harmonic generation on the Titanium-Sapphire tunable laser using an external enhancement cavity containing a critically phase-matched LBO non linear crystal (LiB3O5). Temperature-tuning of the phase-matching condition at a fixed crystal orientation leads to a wide tunability from 390 nm to 405 nm wavelength. The external cavity optical pathlength was actively locked to the laser frequency using a¨Pound-Drever-Hall servo, allowing to extract up to 6 mW power at 400 nm wavelength with a 480 mW pump power. Despite a perfect mode-matching efficiency, the power performance was limited by the poor nonlinear impedance matching of the resonator, due to both the weak nonlinearity of the crystal and the low incoming laser power.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work we present the results of L-asparagine H2O crystal growth and the study of their optical properties, linear and nonlinear, of crystal as grown and after being submitted to high doses of X-ray. Crystals were grown in aqueous solution by the method of slow evaporation of the solvent. Measurements optical absorption, Raman, thermal analysis and efficiency of second harmonic generation were carried out. The results demonstrate the good optical quality of the crystals for use in optical devices, comparable to that of KDP (KH2PO4). . / Neste trabalho apresentamos os resultados do crescimento de cristais de L-Asparagina-H2O e do estudo de suas propriedades ópticas, lineares e não lineares, do cristal como é crescido e após ser submetido a altas doses de raios-X. Os cristais foram crescidos em solução aquosa pelo método de evaporação lenta do solvente. Foram realizadas medidas de absorção óptica, Raman, análise térmica e eficiências de geração de segundo harmônico. Os resultados demonstram as boas qualidades ópticas dos cristais para aplicação em dispositivos ópticos, comparáveis ao do KDP (KH2PO4).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work, we investigated the phenomenon of second harmonic generation in hydrazone compounds. Based on optical absorption measurements, we determined the energy bands corresponding to the first excited state and the energy gap of the compound. Using the X-ray powder diffraction method, we verified the crystalline nature of the samples. The process of second harmonic generation exhibited by these compounds was characterized by the Kurtz and Perry powder method. We noted that these materials have good efficiency at second harmonic generation, being comparable to KDP. The results indicate that these are promising compounds for the development of photonic applications based on second-order nonlinear optical effects. / No presente trabalho, investigamos o fenômeno de geração de segundo harmônico em compostos hidrazônicos. A partir de medidas de absorção ´optica, determinamos as bandas de energia correspondentes aos primeiros estados excitados e a energia do gap dos compostos. Usando a difra¸c˜ao de raio-X m´etodo do p´o, verificamos a natureza cristalina das amostras estudadas. O processo de gera¸c˜ao de segundo harmˆonico exibidos por esses compostos foi caracterizado pelo m´etodo do p´o de Kurtz e Perry. Observamos que esses materiais apresentam boa eficiˆencia de gera¸c˜ao de segundo harmˆonico compar´aveis ao KDP. Os resultados obtidos indicam que esses compostos s˜ao promissores para o desenvolvimento de aplica¸c˜oes fotˆonicas baseado em efeitos ´opticos n˜ao lineares de segunda ordem.

La technique de la génération de second harmonique (SHG) a été employée pour étudier la réponse non linéaire des assemblées de nano particules métalliques aux interfaces liquides. Les nanoparticules ont d’abord été caractérisées en utilisant la génération de second harmonique incohérente, également nommée diffusion hyper Rayleigh. L’étude de particules d’or et d’argent, nanosphères et des nanobâtonnets, ont permis de mettre en évidence l’influence de la couche protectrice de surfactants sur l’hyperpolarisabilité quadratique de ces particules. Ces particules ont ensuite été placées à l’interface air/eau dans une cuve de Langmuir afin d’étudier le rôle des interactions entre les particules sur la réponse optique linéaire et non linéaire. Celle-ci a révélé dans ces films formés à l’interface la présence de couplages forts entre les particules lors de la compression de la surface. Cela conduit à une transition dans le film une fois que la distance entre les particules passe en dessous d’une distance critique. Ces études ont été complétées par des expériences réalisées à l'interface liquide/liquide et sur une électrode de carbone vitreux pour examiner plus en détail le rôle de la rugosité à l’échelle nanométrique dans l’exaltation de la réponse non linéaire SHG / In this work, the nonlinear optical response of assembled metallic nanoparticles at interfaces was studied using Second Harmonic Generation. First, the nanoparticles were characterised using incoherent second harmonic generation, a technique also called Hyper Rayleigh Scattering. Thioalkane-capped silver and gold nanoparticles, both nanospheres and nanorods, were investigated and the role of this capping layer on the quadratic hyperpolarisability of these particles was underlined. The particles were then deposited at the air/liquid interface in a Langmuir trough to investigate the role of the interparticles interactions in large assemblies. Both the linear and the nonlinear optical response of these metallic films formed at the surface of the trough provided evidence of a strong coupling between adjacent particles upon compression leading to a phase transition of the film once the interparticle distance is less than a critical value. These studies were complemented with experiments performed at the liquid/liquid interface and at the glassy carbon/electrolyte interface to examine in greater details the role of roughness at the nanoscale on the enhancement of the SHG response

Dans le cadre de la séparation sélective pour le traitement et la valorisation des combustibles nucléaires usés, l’extraction liquide/liquide est largement utilisée au niveau industriel. Néanmoins, ce procédé est encore mal compris en ce qui concerne les phénomènes physico-chimiques qui se produisent à l’interface liquide/liquide. Ce travail porte sur la compréhension de la dynamique de l’interface liquide nanométrique durant le transfert d’une espèce entre une phase aqueuse et une phase organique. Deux techniques expérimentales ont principalement été utilisées: la mesure de tension interfaciale et l’optique non linéaire. Ce travail a également donné lieu au développement d’un modèle numérique de dynamique de transfert de phase prenant en compte à la fois des phénomènes de transport diffusif proche de l’interface et une cinétique chimique sur l’interface décrivant les processus d’adsorption/désorption. Des systèmes modèles constitués de molécules surfactantes et/ou chromophores et/ou complexantes ont été étudiés aux interfaces air/liquide et liquide/liquide. L’adsorption/désorption, l’agrégation en surface, la complexation d’ion à une interface liquide et la structuration des systèmes ont ainsi pu être étudiées tant d’un point de vue des états d’équilibre que de la dynamique. Enfin, ces études ont été appliquées à un système d’intérêt industriel utilisé dans le procédé de dépollution DIAMEX / Liquid-liquid extraction processes are widely used in the industrial fields of selective separation. Despites its numerous applications, the microscopic mechanisms which occur during a liquid liquid extraction processes are really unknown specially at the liquid/liquid interface. Thus, this work deals on the understanding of the phenomena which drive the mass transfer across a liquid/liquid interface. Two experimental techniques were used in this work: dynamic interfacial tension measurement and non-linear optical experiments. Along with the use of this experimental approach, a numerical model describing the mass transfer dynamic has been developed. This model works under the assumption that both diffusion and a chemical step describing adsorption and desorption processes contribute to the global transfer kinetics. Model systems of surfactant molecules, chromophore molecules and complexing molecule were investigated at liquid/liquid and air/liquid interface. Interfacial phenomena like adsorption, surface aggregation and ion complexing were studied. Finally, the methodology developed in this work was applied to studied an extractant molecule with potential industrial application

Le manuscrit présente une étude de la réponse optique non linéaire quadratique et cubique de nano-structures métalliques d'or déposées sur substrat. Le travail s'inscrit plus généralement dans le domaine de la plasmonique non linéaire et vise à mieux comprendre l'interaction entre les nanostructures et la lumière, dans un régime d'intensités incidentes fortes, lorsque la réponse n'est plus linéaire. Les exaltations des champs électromagnétiques locaux dans ces structures par les résonances de plasmon de surface, excitations collectives des électrons de conduction, favorisent en effet considérablement ces processus. Dans le cadre de la réponse quadratique, l'étude a essentiellement porté sur le processus appelé génération de second harmonique (SHG, acronyme pour Second Harmonic Generation) par lequel deux photons incidents à la fréquence fondamentale sont convertis en un photon à la fréquence harmonique double. Ce processus est fortement dépendant de la morphologie des nanostructures métalliques. Pour la réponse cubique, l'étude a porté sur les effets Kerr optiques qui décrivent la variation de l'indice optique des nanostructures avec l'intensité de l'onde incidente. Une attention toute particulière a été donnée aux conditions géométriques d'éclairement effectué avec une grande ouverture numérique. Le champ électromagnétique incident ne doit en effet plus être considéré dans l'approximation paraxiale / The manuscript reports a study about the quadratic and cubic nonlinear optical response from gold metallic nanostructures which are deposited onto substrates. The field of this work is more commonly known as nonlinear plasmonics and it consists in trying to understand the interaction between nanostructures and light, in a regime of high incident intensities when the response is no longer linear. The local electromagnetic field enhancement in these structures due to the surface plasmon resonance, the latters being collectives excitations of the conduction band electrons, increase drastically the cross-section for these processes. In the context of a quadratic response, the study has been focused on the Second Harmonic Generation (SHG) process whereby two incident photons at the fundamental wavelength are converted into one photon at twice the harmonic frequency. This process is highly dependent to the metallic nanostructures morphology. For the cubic response, the study has been focused on the optical Kerr effect which describes the optical index variation of nanostructure with the intensity of the incident wave.Specifics considerations have been taken into account about the geometrical illumination conditions which are performed with a large numerical aperture. The electromagnetic incident field cannot be anymore considered within the paraxial approximation

Au cours de cette thèse ont été développées de nouvelles techniques de mesure des propriétés mécaniques par nanoindentation, adaptées à des conditions expérimentales difficiles : les très faibles enfoncements, les surfaces rugueuses, et la température. Une simulation numérique par éléments finis d’un échantillon de silice chauffé à 80°C, indenté par un diamant Berkovich dont la température initiale est de 25°C, dans de l’air à 60 °C, a mis en évidence la nécessité de chauffer l’indenteur. De plus, les essais expérimentaux à haute température effectués sur ce même échantillon ont permis de montrer que le signal de déplacement de l’indenteur est fortement perturbé par de faibles variations de température (<0,1°C), rendant le calcul des propriétés mécaniques imprécis avec la technique de mesure classiquement utilisée en nano-indentation. Une nouvelle technique, reposant sur la mesure de l'amplitude de la seconde harmonique du signal de déplacement, a été développée pendant cette thèse. Elle permet la détermination des propriétés mécaniques indépendamment de la mesure de l’enfoncement. Elle est donc adaptée pour des tests à haute température. Elle été expérimentée sur des matériaux homogènes (silice, PMMA), sur un matériau (monocristal de calcite) possédant une dureté plus élevée en surface (Indentation Size Effect), et sur des couches minces de PMMA déposées sur un substrat de silicium, à température ambiante. Les résultats ont montré que les propriétés mécaniques sont mesurées de façon plus précise aux faibles enfoncements. Les essais expérimentaux sur la calcite ont mis en évidence que l'Indentation Size Effect observé sur cet échantillon est mieux détecté avec la technique de la seconde harmonique. Elle permet aussi de calculer la pénétration de l'indenteur a posteriori. Une seconde technique de mesure des propriétés mécaniques, reposant sur le calcul de la dérivée de la hauteur de contact en fonction de la pénétration, a été développée. Elle permet une mesure des propriétés mécaniques des matériaux par nano-indentation plus précise que la méthode classique à température ambiante aux faibles pénétrations. Les mesures sont aussi améliorées sur les échantillons rugueux et pour les essais réalisés à haute température. / The aim of this thesis was the development of new measurement techniques based on nano-indentation, adapted for difficult experimental conditions: small penetration depths, rough surfaces, and high temperature. The thermal contact between a Berkovich indenter initially at 25 °C and a fused silica sample heated at 80 °C, in air at 60 °C, was numerically simulated by finite elements method. The results showed the necessity to heat the indenter in order to avoid effects due to the difference of temperature between the two solids. Furthermore, high temperature nanoindentation tests showed the displacement signal is greatly influenced by temperature variations (<0.1°C), resulting in imprecise mechanical properties calculation. A new experimental technique, based on the measurement of the amplitude of the second harmonic of displacement, was developed. With this method, the determination of the mechanical properties is independent of the indentation depth measurement. So, the second harmonic method is adapted to high temperature tests. It was tested on homogeneous materials (fused silica and PMMA), on a sample which is known to exhibit an Indentation Size Effect (calcite), and on thin PMMA layers deposited onto silicon wafers, at room temperature. With the second harmonic method, the mechanical properties are measured more precisely at small penetration depths. Experiments performed on the calcite sample showed that the Indentation Size Effect is more precisely measured with this new method. Furthermore, the indentation depth can be calculated “a posteriori” with second harmonic method. A second new measurement technique, based on the derivative of the contact depth with respect to the indentation depth, was developed. With this simple method, the mechanical properties are more precisely measured at room temperature at small indentation depths. Measurements are also improved on rough samples and at high temperature.