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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

Hybrid Plasmon Waveguides: Theory and Applications

Alam, Muhammad 06 December 2012 (has links)
The study and applications of surface plasmon polaritons (SP) – also known as plasmonics – has attracted the interest of a wide range of researchers in various fields such as biology, physics, and engineering. Unfortunately, the large propagation losses of the SP severely limit the usefulness of plasmonics for many practical applications. In this dissertation a new wave guiding mechanism is proposed in order to address the large propagation losses of the plasmonic guides. Possible applications of this guiding scheme are also investigated. The proposed hybrid plasmonic waveguide (HPWG) consists of a metal layer separated from a high index slab by a low index spacer. A detailed analysis is carried out to clarify the wave guiding mechanism and it is established that the mode guided by the HPWG results from the coupling of a SP mode and a dielectric waveguide mode. A two dimensional HPWG is proposed and the effects of various parameters on the HPWG performance are analyzed in detail. This structure offers the possibility of integrating plasmonic devices on a silicon platform. The proposed waveguide supports two different modes: a hybrid TM mode and a conventional TE mode. The hybrid TM mode is concentrated in the low index layer, whereas the conventional TE mode is concentrated in the high index region. This polarization diversity is used to design a TM- and a TE-pass polarizer and a polarization independent coupler on a silicon-on-insulator (SOI) platform. Moreover, the performance of a HPWG bend is investigated and is compared with plasmonic waveguide bends. The proposed devices are very compact and outperform previously reported designs. The application of HPWG for biosensing is also explored. By utilizing the polarization diversity, the HPWG biosensor can overcome some of the limitations of plasmonic sensors. For example, unlike plasmonic sensors, the HPWG biosensor can remove the interfering bulk and surface effects.
2

Hybrid Plasmon Waveguides: Theory and Applications

Alam, Muhammad 06 December 2012 (has links)
The study and applications of surface plasmon polaritons (SP) – also known as plasmonics – has attracted the interest of a wide range of researchers in various fields such as biology, physics, and engineering. Unfortunately, the large propagation losses of the SP severely limit the usefulness of plasmonics for many practical applications. In this dissertation a new wave guiding mechanism is proposed in order to address the large propagation losses of the plasmonic guides. Possible applications of this guiding scheme are also investigated. The proposed hybrid plasmonic waveguide (HPWG) consists of a metal layer separated from a high index slab by a low index spacer. A detailed analysis is carried out to clarify the wave guiding mechanism and it is established that the mode guided by the HPWG results from the coupling of a SP mode and a dielectric waveguide mode. A two dimensional HPWG is proposed and the effects of various parameters on the HPWG performance are analyzed in detail. This structure offers the possibility of integrating plasmonic devices on a silicon platform. The proposed waveguide supports two different modes: a hybrid TM mode and a conventional TE mode. The hybrid TM mode is concentrated in the low index layer, whereas the conventional TE mode is concentrated in the high index region. This polarization diversity is used to design a TM- and a TE-pass polarizer and a polarization independent coupler on a silicon-on-insulator (SOI) platform. Moreover, the performance of a HPWG bend is investigated and is compared with plasmonic waveguide bends. The proposed devices are very compact and outperform previously reported designs. The application of HPWG for biosensing is also explored. By utilizing the polarization diversity, the HPWG biosensor can overcome some of the limitations of plasmonic sensors. For example, unlike plasmonic sensors, the HPWG biosensor can remove the interfering bulk and surface effects.
3

Adressage et contrôle de nanosources optiques par plasmonique intégrée ou fibrée / Addressing and control of optical nanosources by integrated or fibered plasmonics

Barthes, Julien 18 June 2015 (has links)
Les plasmons polaritons de surface, modes supportés par des nanostructures métalliques permettent de confiner la lumière à des échelles sub-longueurs d’onde. En s’affranchissant de la limite de diffraction, ces modes constituent des pistes intéressantes pour l’adressage et le contrôle de nanosources optiques (molécules, boites quantiques...). Par exemple, un nanofil métallique constitue un guide plasmonique unidimensionnel qui permet d’exciter une nanosource ou encore de coupler deux émetteurs avec des applications possibles pour la réalisation de composants nano-optiques intégrés. En revanche, la perte d’énergie dans le métal diminue la portée de ces dispositifs. Une stratégie consiste donc à travailler sur une configuration hybride : plasmonique et fibre optique, pour coupler efficacement l’émission de la nanosource à un mode de fibre. Ceci ouvre la voie à la réalisation d’une nanosource fibrée de manipulation aisée pouvant être utilisée comme source de photon unique pour la cryptographie quantique ou plus simplement comme une sonde de champ proche optique haute résolution.Après une étude des principaux canaux de relaxation d’une molécule fluorescente à proximité d’un guide plasmonique, nous discutons de l’optimisation du couplage entre l’émetteur et le guide plasmonique en jouant sur sa forme et la longueur d’onde d’émission. Ensuite, nous nous intéressons au comportement d’une structure hybride composée d’une fibre optique étirée et métallisée. Enfin, nous montrons que l’optimisation du transfert d’énergie d’une molécule fluorescente en présence de cette structure permet de collecter plus de 50% de l’énergie lumineuse d’un nano-émetteur posé sur un substrat vers une fibre optique par le truchement d’un plasmon. / Surface plasmon polariton (SPP) can confine light on subwavelength dimensions. Since they are not diffraction limited, they are of great interest for addressing and controlling optical nanosources. For example, a metal nanowire defines 1D plasmonic waveguide with a great potential for either addressing or coupling quantum emitters. Therefore, SPP opens great opportunities for integrated optical applications. However, SPP suffer from ohmic losses that jeopardize the applications of plasmonic components. In this context, we study the possibilities provided by an hybrid plasmonic-photonicstructure to couple efficiently an emitter to a fiber mode. Such a structure paves the way for fibered single photon nanosource or high resolution optical probe. In this thesis manuscript, we first study the coupling rate between a fluorescent molecule and a metallic nanowire thanks to Green’s dyad formalism. This leads us to distinguish the different relaxation channels and the enhancement of the energy transferred into the plasmonic guided mode by optimizing the shape of the guide (crystalline nano-wire,slow modes). Then, we investigate the energy propagation in a metal coated taperedoptical fiber. Finally, we achieve an optimal configuration for which more than 50% of the energy emitted by a quantum emitter laid on a substrat is transferred into an optical fiber.

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