Band energy approach and nonlinear optical phenomena in large-sized nanoparticles, Journal of Telecommunications and Information Technology, 2006, nr 4

This report presents principal optical properties of semiconducting large-sized nanocrystalline (LSNC) material with thickness within 10–50 nm range. A quantitative parameter for description of the LSNC state is introduced. Influence of the surrounding polymer matrices on the properties of the LSNC is shown. Role of the surrounding polymer matrix background in the manifestation of material optoelectronic properties is studied. Superposition of long-range ordering with the localized nano-quantized effects is analyzed within a framework of different one-electron band energy approaches. Manifestation of the LSNC nonlinear optical (NLO) properties will be presented separately. It is clearly demonstrated that appropriate choice of LSNC geometry parameters together with proper modification of chemical composition could enhance the key NLO parameters

Etude des effets optiques photo-induits dans les métallo-composites et analyse de leurs caractéristiques surfaciques par microscopie à force atomique

La thèse présente analyse les phénomènes photo-induits optiques dans les métallo-composites avec l'utilisation du microscope à force atomique. Le sujet de l'analyse sont les ITO (indium tin oxide), FTO (fluorine tin oxide) et ZnO qui comportent des métallo-composites d'argent et d'or. Les dimensions de ces métallo-composites sont à peu près égales à 60-80 nm. les couches d'ITO et FTO ont de très interessantes propriétés optiques et électriques. Avec ces matériels se construisent des diodes électro luminescentes organiques, des écrans à crsitaux liquides et des écrans plasmaREIMS-BU Sciences (514542101) / SudocSudocFranceF

Etude des effets optiques du deuxième et troisième ordre photo induits dans des complexes alkynyls à base de ruthénium

Ce travail de thèse est consacré aux études théoriques et expérimentales des effets optiques non linéaires du second et troisième ordre photo induits dans de nouveaux complexes alkynyls à base de ruthénium. L objectif principal de ce travail est de déterminer l influence des structures chimiques des composés organométalliques fonctionnalisées sur les propriétés optiques non linéaires du 2ème et 3ème ordre à l aide des techniques de poling optique de génération du second harmonique (PISHG), de génération du second harmonique optique induite acoustiquement (AIOSHG) et du mélange quatre ondes dégénéré (DFWM). Nous avons démontré l influence de la matrice sur la cinétique des processus optiques non linéaires du 3ème ordre dans les complexes organométalliques. Nous avons démontré que l incorporation des dérivés ruthénium-alkynyl dans des matrices polymères (PVK et PMMA) entraîne une augmentation des propriétés optique non linéaires et que leur rôle est crucial dans la compréhension des phénomènes observés. Un bon accord entre les résultats expérimentaux et les simulations est obtenu. Il s agit d une contribution à la fois importante et utile dans le domaine des matériaux fonctionnels car nous avons démontré que ces composés sont multifonctionnels et l originalité de ce travail consiste surtout en un choix judicieux des composés suivant leur potentialité d application en optoélectronique.The thesis is devoted to the theoretical and experimental studies of Photo-induced second and third order optical effects in ruthenium alkynyl push pull complexes. The main goal of this work was to determine the influence of the chemical structures of the organometallic compounds on the second and third-order nonlinear optical properties using optically and acoustically induced second harmonic generation (AISHG) and degenerate four wave mixing (DFWM) experiments. The investigation of kinetics of the third order nonlinear optical processes in organometallic complexes is also presented. The alkynyl ruthenium derivatives were embedded in polymethyl methacrylate (PMMA) and polyvinylcarbazole (PVK) polymer matrix. We showed that the influence of the polymer matrix play crucial role for the kinetics of the observed behaviour in the Ru-containing chromophore. The originality of this work consists especially on judicious choice of studied compound according to their potential applications in optoelectronics. We showed a good correlation between the chemical structures and the nonlinear optical properties. We also demonstrate their potentiality for the applications in nonlinear optics (SHG, AISHG,THG) and recently as like optical memories in picoseconds regime.ANGERS-BU Lettres et Sciences (490072106) / SudocSudocFranceF

Photoinduced Absorption and Birefringence Changes in Complex Chalcogenide Crystals AgxGaxGe1-xSe2 (0,167 ≤ x ≤ 0,333)

Четвертинні монокристали AgxGaxGe1-XSe2 (х = 0,333, 0,250, 0,200 і 0,167) були вирощені методом Стокбаргера Бріджмена. Досліджено спектральні залежності фотоіндукованого поглинання в нелегованих кристалах селеніду при опроміненні лазерними імпульсами з довжиною хвилі 808 нм. Представлено динаміку фотоіндукованого оптичного поглинання AgGaGe3Se8:Cu під вливом 532 нм та 1300 нм лазерного випромі- нювання CW.; Quaternary crystals AgxGaxGe1- XSe2 (x = 0.333, 0.250, 0.200 and 0.167) were grown by Bridgman Stockbarger. Spectral dependence of photoinduced absorption in undoped selenide crystals irradiated laser pulses with a wavelength of 808 nm. The dynamics of photoinduced optical absorption AgGaGe3Se8: Cu at 532 nm poured and 1300 nm laser CW. The changes of the birefringence demonstrate substantial changes of time kinetics depending on the pumping wavelengths. It was found that the changes of the photoinduced birefringence are at least 4 times higher for the 532 nm pumping wavelength with respect to the 1300 nm wavelength. The Ag cations, Cu dopants and local trapping levels play here crucial role

Noncentrosymmetric Sulfide Oxide MZnSO (M = Ca or Sr) with Strongly Polar Structure as Novel Nonlinear Crystals

We performed a comprehensive ab inito calculation to investigate the influence of substitution of Ca2+ (180 pm) by larger Sr2+ (200 pm) in MZnSO (M = Ca or Sr) on the structural properties and, hence, on the linear and nonlinear optical properties. The substitution of Ca2+ by Sr2+ in MZnSO causes a band gap reduction resulting in an influence on the photophysical properties and enhances the optic activity toward the visible region. The observation of linear optical properties reveals a band gap reduction on moving from Ca to Sr, and the whole spectral structure shifts toward lower energies. The substitution of Ca2+ by Sr2+ introduces an obvious enhancement in the anisotropy between the extraordinary and ordinary tensor components, as confirmed by the uniaxial anisotropy and birefringence favoring an important role in second harmonic generation (SHG) and optical parameter oscillator due to better fulfilling of phase-matching conditions. The calculations show that SrZnSO exhibits larger SHG and microscopic first hyperpolarizability (βijk) than CaZnSO. © 2019 American Chemical Society

Non-Linear Optical Effects in Au Nanoparticle-Deposited ZnO Nanocrystalline Films

Abstract. Applying a bicolor coherent treatment of a Nd-YAG laser with wavelength 1.32 µm and its second harmonic generation, we have investigated photoinduced SHG in Au nanoparticledeposited ZnO nanocrystallinne (NC) films. We have established that coexistence of the such crystallites gives substantially better results compared to the pure ZnO NC deposited onto the glass substrate. It was shown that the value of the second order susceptibility obtained for the large incident angles of the fundamental and writing beams is equal to about 23 pm/V. The better results are obtained during the phototreatment at temperatures near the 60 o C for the Au doped samples and is almost non-sensitive to temperature for the pure samples. The further increase of the temperature leads to decay of the optical second harmonic generatio