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 “"phonon polariton"”.
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Phonon polariton interaction with patterned materials
The generation, propagation and detection of THz phonon polaritons are studied through both femtosecond pump-probe techniques, and Finite Difference Time Domain (FDTD) simulations in this thesis. The theory surrounding the driving, propagation and detection of these modes is treated in a consistent …
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Modeling phonon-polariton generation and control in ferroelectric crystals
… using Finite Element Method (FEM), of phonon-polariton generation and coherent control in ferroelectric crystals LiNbO₃ and LiTaO₃ through nonlinear electro-optic interactions with ultrashort laser pulses. This direct space-time monitoring platform is used to investigate the nature of …
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Design of Phonon Polariton Propagation in Thin Layers of Highly Anisotropic Materials
… últimas décadas es la conversión de la luz en polaritones superficiales (luz acoplada a excitaciones dipolares en la materia). Estas ondas electromagnéticas superficiales exhiben un fuerte confinamiento espacial debido a su decaimiento evanescente, así como longitudes de onda que pueden ser …
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Frequency-resolved ultrafast dynamics of phonon polariton wavepackets in the ferroelectric crystals LiNbO₃ and LiTaO₃
… enables to study the selective excitation of phonon polaritons. These quasi-particles arise from the coupling of electro-magnetic waves and transverse optical lattice modes, the so-called phonons. The phonon polaritons were investigated in the optically non-linear, ferroelectric crystals …
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Development of phonon-polarization THz spectroscopy, and the investigation of relaxor ferroelectrics
This thesis develops phonon-polariton based THz spectroscopy and uses this technique to make the first THz frequency dielectric measurements of a relaxor ferroelectric crystal, in particular KTao0.982Nb0.018O3 (KTN 1.8). THz spectroscopy has emerged as an important probe for a wide variety of …
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Polaritonics : an intermediate regime between electronics and photonics
… the foundational work behind the field of polaritonics. Corresponding to a frequency range from roughly 100 gigahertz up to 10 terahertz, polaritonics bridges the gap between electronics and photonics. In this regime, signals are carried by an admixture of electromagnetic and lattice …
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Electrically-tunable near-field heat transfer with ferroelectric materials
… by orders of magnitude via the use of surface phonon polariton or plasmon polariton waves. This enhancement has potential applications in different devices, such as thermal emitters, thermal rectifiers, thermophotovoltaic and thermoelectric energy conversion systems. In this thesis, the author …
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Reststrahlen band optics for the advancement of far-infrared optical architecture
… probe the possible means of linking bulk optical phonon populations through interaction with surface modes to free space photons. This is a breakthrough that would enable the development of a new class of light sources operating in the far-infrared. Chapter 1 introduces the far-infrared wavelength …
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Energy transmission through and along thin films mediated by surface phonon-polaritons
Surface phonon-polaritons are hybrid electromagnetic modes that are the result of photons coupling to transverse optical phonons. Recently, these surface modes have received much renewed interest primarily due to the fact that micro-fabrication techniques can now routinely create structures at the …
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Harvesting photon energy : ultra-thin crystalline silicon solar cell & near-field thermoradiative cells
… Near-field radiative transfer, especially using phonon polariton material to couple out emitted photons from electron-hole recombination, is proposed to enhance energy conversion efficiency as well as the power density. We predict that the InSb thermoradiative cell can achieve the efficiency and …
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THz polaritonics : control, confinement, and strong light-matter interactions
On the terahertz (THz) polaritonics platform, ultrafast optical laser pulses are used to generate and detect THz phonon-polariton wavepackets with full spatiotemporal resolution while they are confined to a thin slab of lithium niobate (LN) or lithium tantalate (LT) that is roughly 30-100 pm thick. …
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Experimental investigations of the role of proximity approximation in near-field radiative transfer
… when they can support electromagnetic surface polaritons because of the high local density of states at the interface between the object and vacuum. When two objects of polar dielectric materials are close enough, the enhanced near-field radiation due to surface phonon polariton tunneling can …
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Manipulated Electrochemical Surface Reactions Induced By Oscillatory Electric Potentials on Metal Based Electrodes
… d-band center on the metallic surface, a photon-phonon interaction leading to the creation of a phonon-polariton, and/or the evolution of a complex three dimensional field with surface normal. When investigating a multilayered ceramic electrochemical catalytic membrane for automotive emission …
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Excitation, Interaction, and Scattering of Localized and Propagating Surface Polaritons
Surface polaritons, i.e., collective oscillations of the surface charges, strongly influence the optical response at the micro- and nanoscale and have to be accounted for in modern nanotechnology. Within this thesis, certain basic phenomena involving surface polaritons are investigated by means of …
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A Theoretical Study on the Effect of Curvature on Near-field Radiative Transfer
… polar dielectric materials which support surface phonon polaritons (SPPs). When two such bodies are brought in close proximity to each other, the enhanced near-field radiation due to tunneling of SPPs can exceed the classical black body limit by several orders of magnitude. This enhanced radiation …