Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"Negative Refraction"”.
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Anomalous photon phenomena in electromagnetic crystal systems
… range that appeared to exhibit simultaneously negative values of permittivity and permeability. Such substances were known as "left-handed materials," and had been predicted to enable a variety of anomalous electromagnetic effects. Intense interests have developed in these materials after …
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Homogenization of Structured Metasurfaces and Uniaxial Wire Medium Metamaterials for Microwave Applications
… due to their extraordinary properties such as negative refraction, partial focusing, enhanced transmission, and spatial filtering, among others. Artificial media are crystals of various periodic metallic inclusions with dimensions of the order of ?/10 - ?/4. When compared to natural materials, …
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Simulation of Simultaneously Negative Medium Metamaterials
… permeability of values less than 1, including negative values. If the material has negative permittivity and permeability at the same time, the material is also referred to as simultaneously negative medium (DNG medium). Such medium has several features that any natural medium is not equipped …
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Photonic Crystals with Alternate Arrays of Rods and Holes in a Low Dielectric-Index Material
… manifested by perfect reflection, negative refraction, and superlensing. I then extended my work to three dimensional (3D) counterparts of the discovered PhCs, which are called photonic crystal slabs (PCSs). I found that the overlapped TE and TM PBGs persist in these PCSs although …
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Electromagnetic properties and macroscopic characterization of composite materials
… left-handed triad, scattering enhancement, and negative refraction. In this thesis, the microscopic/macroscopic properties, the control of the geometry and functionality, and potential applications of various composites are explored. Numerical and theoretical tools are presented for the purpose …
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Dynamic Metasurfaces for Advanced Applications
… and exotic properties such as flat lenses, negative refraction, and perfect absorption. In this work significant advances are made in two main areas. First we explore the subject of the all dielectric metasurface, implemented as arrays of dielectric cylinders. Here, we improve upon the …
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Understanding new regimes for light-matter interactions
… a 3D photonic crystal slab structure to exhibit negative-index behavior at visible wavelengths, which was fabricated and experimentally demonstrated by our collaborators to show negative refraction with, to our knowledge, the lowest loss at visible wavelengths to date.
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Theory, Simulation, Fabrication and Testing of Double Negative and Epsilon Near Zero Metamaterials for Microwave Applications
<p>Natural structures exhibiting simultaneous negative bulk permittivity and permeability have not yet been discovered. However, research interest over the past five years has grown with the proposition that artificial structures exhibiting these properties are realizable using specially-designed …
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Breaking symmetries in ordered materials : spin polarized light transport in magnetized noncentrosymmetric 1D photonic crystals, and photonic gaps and fabrication of quasiperiodic structured materials from interference lithography
… phase and group velocities) which enable negative refraction at the air-crystal interface, ability to allow bending light with perpendicular magnetic fields, unidirectional superprism effects, etc. By calculating the complex photonic band structure, we show that the gap modes differ …
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Design of elastic metamaterials
… material properties of the metamaterials. Negative phase velocity in the double negativity metamaterial was also demonstrated.</p> <p>For metamaterials with single negativity, three types of broadband metamaterials were designed from parametric studies. A comparison showed that using frame …
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Wave propagation and imaging in structured optical media
… of imaging systems. In particular, we show a negative refraction lens based on the photonic hypercrystals, which possesses a nearly constant negative refractive index and can be used to substantially reduce the image aberrations. We apply similar ideas in purely dielectric photonic crystals …
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Analysis of Periodic and Random Capacitively-Loaded Loop (CLL) Metamaterial Structures for Antenna Enhancement Applications
… to exhibit exotic material properties, such as negative refractive index, by exploiting features in arrays of sub-wavelength unit inclusions. These unconventional electromagnetic properties are realized through the coupling of the microscopic unit inclusions, which govern the macroscopic …
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Anomalous phenomena and spectral tailoring in photonic crystals
… around a zero-group velocity point. Motivated by negative refraction, a measure of the effective wavevector is constructed that distinguishes various types of zerogroup velocity modes. Around one type of zero-group velocity mode, an anomalous region of backward effective wavevector is found that …
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All-optical metamaterial modulators : fabrication, simulation and characterization
… features of metamaterials is to obtain negative refraction, termed left-handed materials or negative-index metamaterials, over a limited frequency band. Negative-index metamaterials at near infrared wavelength are fabricated with circular, elliptical and rectangular holes penetrating …
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Wavefront Engineering and Computational Sensing with Acoustic Metamaterials
… two kinds. The first kind of devices, including negative refraction prism, planar acoustic lenses, beam-steering metasurfaces and phase acoustic holograms, control the propagation or the states of existence of acoustic waves. The second kind focuses on a reciprocal process—instead of controlling …
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Analysis and Experimental Investigation of Wave Propagation and Energy Transfer in Mechanical Rotator Metamaterials
… locations. This leads to amplitude-dependent negative refraction at the interface between these lattices. The dissertation further delves into the morphing of the dispersion relationship through rotational geometry, yielding a stretchable rotator lattice capable of extreme acoustoelastic …
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Resonance Fluorescence in a Photonic Crystal
… absorbing crystals are found; defect modes and negative refraction are discussed. The quantum optics section of the work starts with the discussion of three problems, that are related to the full resonance fluorescence problem: a pure dephasing model, the driven atom and resonance fluorescence …
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Acoustic metamaterial design and applications
… opportunity to develop an artificial media with negative refractive index and the application in superlens which allows super-resolution imaging. High-resolution acoustic imaging techniques are the essential tools for nondestructive testing and medical screening. However, the spatial resolution …
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Graphene Based Metamaterials For Terahertz Cloaking And Subwavelength Imaging
… electromagnetic applications – including negative refraction, subdiffraction imaging, and even invisibility – which have suggested a wide range of new devices for communications, sensing, and biomedicine. In addition, it has been shown that graphene is amenable to unique patterning schemes …
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Ultrathin metasurface devices for phase and polarization control
… concepts and new discoveries to the world (e.g., negative refraction, super imaging and cloaking). However, the application of 3D metamaerials in the optical range is limited by current nanofabrication techniques. As 2D counterparts of metamaterials, metasurfaces, which are comprised of a single …
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