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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Unraveling photonic bands: characterization of self-collimation effects in two-dimensional photonic crystals

Yamashita, Tsuyoshi 15 June 2005 (has links)
Photonic crystals, periodic dielectric structures that control photons in a similar way that atomic crystals control electrons, present opportunities for the unprecedented control of light. Photonic crystals display a wide gamut of properties, such as the photonic band gap, negative index of refraction, slow or stationary modes, and anomalous refraction and propagation effects. This thesis investigates the modeling, simulation, fabrication, and measurement of two-dimensional square lattice photonic crystals. An effective index model was developed to describe the propagation of electromagnetic waves in the media and applied to characterize the behavior of self-collimated beams to discern the effect of the photonic crystal on the evolution of the amplitude and phase of the propagating beam. Potential applications include optical interconnects and stand alone devices such as filters and lasers. Based on design parameters from the simulations, two dimensional photonic crystals were fabricated on amorphous and single crystal silicon-on-insulator substrates utilizing electron beam lithography and inductively coupled plasma etching. A unique etching process utilizing a combination of Cl2 and C4F6 gases was developed and characterized which displayed a vertical profile with a sidewall angle of under 1 degree from vertical and very smooth sidewalls for features as small as 150 nm. The high quality of the etching was the key to obtaining extremely low loss, low noise structures, making feasible the fabrication of large area photonic crystal devices that are necessary to measure propagation phenomena. Reflectivity measurements were used to directly observe the photonic band structure with excellent correlation with theory. A device was designed and fabricated which successfully verified the prediction of the simulations through measurements of the self-collimation effect across a broad range of infrared wavelengths. A solid foundation for the necessary components (simulation, modeling, design, fabrication, and measurement) of two-dimensional photonic crystal has been demonstrated. Elements from solid state physics, materials science, optics, and electromagnetics were incorporated to further the understanding of the mechanism of beam propagation in photonic crystals and illuminating the vast potential of research in periodic media.
2

Plasmonic devices for surface optics and refractive index sensing

Stein, Benedikt 03 July 2012 (has links) (PDF)
In this thesis devices for controlling the flow of surface plasmon polaritons are described. Dielectric and metallic nanostructures were designed for this purpose, and characterized by leakage radiation microscopy in real and in reciprocal spaces. Manipulation of surface plasmons by dielectric lenses and gradient index elements is presented, and negative refraction, steering and self-collimation of surface plasmons in one- and two-dimensional plasmonic crystals is demonstrated. The achieved degree of control was applied for routing of nanoparticles by optical forces, as well as for two methods of enhancing the figures of merit of plasmonic refractive index sensors, based on the one hand on Fano resonances natural to leakage radiation microscopy, and on the other hand on anisotropie plasmonic bandstructures.
3

Plasmonic devices for surface optics and refractive index sensing / Composants plasmoniques pour l'optique de surface et la mesure de faibles variations d'indice

Stein, Benedikt 03 July 2012 (has links)
Ce manuscrit s'inscrit dans le contexte du contrôle de la propagation des plasmons de surface. A cet effet, des nanostructures diélectriques et métalliques ont été conçues et caractérisées par microscopie à champ de fuite dans les espaces réels et réciproques. La manipulation des plasmons de surface à l'aide de lentilles diélectriques et d' éléments à gradient d'indice est présentée, et la réfraction négative, la direction et l'auto-collimation des plasmons de surface dans des cristaux plasmoniques à une ou deux dimensions sont démontrées. Ces résultats ont été utilisés pour le guidage de nanoparticules à l'aide de forces optiques, ainsi que pour deux méthodes permettant de renforcer le facteur de mérite de sondes plasmoniques de variation d'indice de réfraction, basées l' une sur les résonances de Fano naturelles de la microscopie à champ de fuite, et pour la seconde sur les structures des bandes plasmoniques anisotropes. / In this thesis devices for controlling the flow of surface plasmon polaritons are described. Dielectric and metallic nanostructures were designed for this purpose, and characterized by leakage radiation microscopy in real and in reciprocal spaces. Manipulation of surface plasmons by dielectric lenses and gradient index elements is presented, and negative refraction, steering and self-collimation of surface plasmons in one- and two-dimensional plasmonic crystals is demonstrated. The achieved degree of control was applied for routing of nanoparticles by optical forces, as well as for two methods of enhancing the figures of merit of plasmonic refractive index sensors, based on the one hand on Fano resonances natural to leakage radiation microscopy, and on the other hand on anisotropie plasmonic bandstructures.

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