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 15 of 15 for “"Negative refractive index."”.
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On Generalized Solutions to Some Problems in Electromagnetism and Geometric Optics
… part of this thesis deals with materials having negative refractive index. Materials which possess a negative refractive index were postulated by Veselago in 1968, and since 2001 physicists were able to construct these materials in the laboratory. The research on the behavior of these materials, …
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Investigation of resonators loaded periodic structures
… ago, substances which exhibit simultaneously, negative permittivity ([epsilon]) and negative permeability ([mu]) over a certain range of frequencies would display some unusual phenomena such as backward waves, reversed refraction, backward Cerenkov radiation, and negative refractive index. …
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Effects of statistical variations on propagation of electromagnetic waves in disordered periodic structures
… investigation of transmission properties of a negative refractive index structure demonstrates its use for expedient assessment of the impact of statistical variations in unit cell length and the values of the lumped inductive and capacitive elements used in the definition of the structure. …
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Uniaxial optical phase change metamaterials
… unconventional optical properties like a negative refractive index can be achieved over a broadband wavelength range of operation. By incorporating optical phase change materials, materials with outstanding optical contrast upon a solid-state phase transition, more control over the optical …
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Applications of light propagation in novel photonic devices
… of the propagating light. In particular, negative refractive index materials have been shown to support fast and/or slow propagating light, whilst two dimensional nonlinear photonic crystals have been used to demonstrate multiple harmonic generation over a wide range of phase matching …
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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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Circular Bessel field statistics and the pursuit of far-subwavelength resolution
… visible light. Along different lines, a perfect negative refractive index can act as a superlens, but realistic materials render this approach ineffective. A method to tune the lens material properties is shown to provide enhanced resolution.</p>
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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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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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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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Analysis, design, and implementation of a reconfigurable fractal volumetric left-handed metamaterial
At the present time, one of the greatest goals to exploit the advantages of Volumetric Left-handed Metamaterials (LHM) is overcoming their very narrow operational bandwidth. This thesis proposes two schemes to efficiently solve this difficulty: 1) a mechanism which reconfigures, at will, the …
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Development and characterisation of phosphate glasses for athermalisation
… athermal glasses must exhibit negative refractive index change with temperature (dn/dT) to counter the effect of thermal expansion. Phosphate glasses are ideal candidates for athermalisation as they exhibit negative dn/dT. An interferometer set-up has been constructed to …
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modeling and application of nonlinear metasurface
… nonlinear medium with novel features such as negative refractive index, magneto-electric coupling‒provide novel nonlinear features not available in nature. Compared to conventional optical components that often extend many wavelengths in size, nonlinear metasurfaces are flexible and extremely …
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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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Creation of 3-dimensional micro-optical materials
… optical phenomena, such as photonic band gaps, negative refractive index, transformation optics, and sub-diffraction limit focusing, to name a few. These phenomena have great implications for our ability to control light, whether it is in its spectral emission and absorption, in directional …