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Analysis of Plasmonic Metastructures for Engineered Nonlinear NanophotonicsSaad-Bin-Alam, Md 30 April 2019 (has links)
This Master’s dissertation focuses on engineering artificial nanostructures, namely, arrays of metamolecules on a substrate (metasurfaces), with the goal to achieve the desired linear and nonlinear optical responses. Specifically,
a simple analytical model capable of predicting optical nonlinearity of an
individual metamolecule has been developed. The model allows one to estimate the nonlinear optical response (linear polarizability and nonlinear hyperpolarizabilities) of a metamolecule based on the knowledge of its shape,
dimensions, and material. In addition, a new experimental approach to measure hyperpolarizability has also been investigated. As another research effort, a 2D plasmonic metasurface with the collective behaviour of the metamolecules known as hybrid plasmonic-Fabry-Perot cavity and surface lattice resonances was designed, fabricated and optically characterized. We experimentally discovered a novel way of coupling the microcavity resonances and the diffraction orders of the plasmonic metamolecule arrays with the low-quality plasmon resonance to generate multiple sharp resonances with the higher quality factors. Finally, we experimentally observed and
demonstrated a record ultra-high-Q surface lattice resonance from a plasmonic metasurface. These novel results can be used to render highly efficient
nonlinear optical responses relying on high optical field localization, and can
serve as the stepping stone towards achieving practical artificial nanophotonic devices with tailored linear and nonlinear optical responses.
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Design, characterisation and biosensing applications of nanoperiodic plasmonic metamaterials / Conception, caractérisation et applications de métamatériaux nanopériodiques plasmoniques pour biocapteursDanilov, Artem 11 April 2018 (has links)
Cette thèse considère de nouvelles architectures prometteuses des métamatériaux plasmoniques pour biosensing, comprenant: (I) des réseaux périodiques 2D de nanoparticules d'Au, qui peuvent supporter des résonances des réseaux de surface couplées de manière diffractive; (II) Reseaux 3D à base de cristaux plasmoniques du type d'assemblage de bois. Une étude systématique des conditions d'excitation plasmonique, des propriétés et de la sensibilité à l'environnement local dans ces géométries métamatérielles est présentée. On montre que de tels réseaux peuvent combiner une très haute sensibilité spectrale (400 nm / RIU et 2600 nm / RIU, ensemble respectivement) et une sensibilité de phase exceptionnellement élevée (> 105 deg./RIU) et peuvent être utilisés pour améliorer l'état actuel de la technologie de biosensing the-art. Enfin, on propose une méthode de sondage du champ électrique excité par des nanostructures plasmoniques (nanoparticules uniques, dimères). On suppose que cette méthode aidera à concevoir des structures pour SERS (La spectroscopie du type Raman à surface renforcée), qui peut être utilisée comme une chaîne d'information supplémentaire à un biocapteur de transduction optique. / This thesis consideres novel promissing architechtures of plasmonic metamaterial for biosensing, including: (I) 2D periodic arrays of Au nanoparticles, which can support diffractively coupled surface lattice resonances; (II) 3D periodic arrays based on woodpile-assembly plasmonic crystals, which can support novel delocalized plasmonic modes over 3D structure. A systematic study of conditions of plasmon excitation, properties and sensitivity to local environment is presented. It is shown that such arrays can combine very high spectral sensitivity (400nm/RIU and 2600 nm/RIU, respectively) and exceptionally high phase sensitivity (> 105 deg./RIU) and can be used for the improvement of current state-of-the-art biosensing technology. Finally, a method for probing electric field excited by plasmonic nanostructures (single nanoparticles, dimers) is proposed. It is implied that this method will help to design structures for SERS, which will later be used as an additional informational channel for biosensing.
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