Plasmonic band gap cavities

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buir.advisorAydınlı, Atilla
dc.contributor.authorKocabaş, Aşkın
dc.date.accessioned2016-01-08T18:04:27Z
dc.date.available2016-01-08T18:04:27Z
dc.date.issued2008
dc.departmentDepartment of Physicsen_US
dc.descriptionAnkara : The Department of Physics and the Institute of Engineering and Science of Bilkent University, 2008.en_US
dc.descriptionThesis (Ph.D.) -- Bilkent University, 2008.en_US
dc.descriptionIncludes bibliographical references leaves 46-51.en_US
dc.description.abstractSurface plasmon polaritons (SPP’s) are trapped electromagnetic waves coupled to free electrons in metals that propagate at the metal-dielectric interfaces. Due to their surface confinement and potential in sub-wavelength optics, SPP’s have been extensively studied for sensing and nanophotonic applications. Dielectric structures and metallic surfaces, both periodically modulated, can form photonic band gaps. Creating a defect cavity region in the periodicity of dielectrics allows specific optical modes to localize inside a cavity region. However, despite the demonstration of numerous plasmonic surfaces and unlike its dielectric counterparts, low index modulation in metallic surfaces limits the formation of plasmonic defect cavity structures. This thesis describes new approaches for plasmonic confinement in a cavity through the use of selective loading of grating structures as well as through the use of Moiré surfaces. In our first approach, we demonstrate that a high dielectric superstructure can perturb the optical properties of propagating SPPs dramatically and enable the formation of a plasmonic band gap cavity. Formation of the cavity is confirmed by the observation of a cavity mode in the band gap both in the infrared and the visible wavelengths. In addition to the confinement of SPP’s in the vertical direction, such a cavity localizes the SPP’s in their propagation direction. Additionally, we have demonstrated that such biharmonic grating structures can be used to enhance Raman scattering and photoluminescence (PL). Using biharmonic grating structure 105 times enhancement in Raman signal and 30 times enhancement in PL were measured. Furthermore, we show that metallic Moiré surfaces can also serve as a basis for plasmonic cavities with relatively high quality factors. We have demonstrated localization and slow propagation of surface plasmons on metallic Moiré surfaces. Phase shift at the node of the Moiré surface localizes the propagating surface plasmons in a cavity and adjacent nodes form weakly coupled plasmonic cavities. We demonstrate group velocities around v = 0.44c at the center of the coupled cavity band and almost zero group velocity at the band edges can be achieved. Furthermore, sinusoidally modified amplitude about the node suppresses the radiation losses and reveals a relatively high quality factor for plasmonic cavities.en_US
dc.description.degreePh.D.en_US
dc.description.statementofresponsibilityKocabaş, Aşkınen_US
dc.format.extentxvi, 95 leaves, illustrations, graphsen_US
dc.identifier.urihttp://hdl.handle.net/11693/14669
dc.language.isoEnglishen_US
dc.publisherBilkent Universityen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectPlasmonics,en_US
dc.subjectMoiré surfaceen_US
dc.subjectSERSen_US
dc.subjectCavityen_US
dc.subjectBand gapen_US
dc.subjectBiharmonic gratingen_US
dc.subjectSurface plasmon polaritonsen_US
dc.subject.lccQC176.8.P55 K63 2008en_US
dc.subject.lcshPlasmons (Physics)en_US
dc.subject.lcshSurfaces (Physics)en_US
dc.subject.lcshPolaritons (Physics)en_US
dc.subject.lcshMoire method.en_US
dc.titlePlasmonic band gap cavitiesen_US
dc.typeThesisen_US

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