This thesis presents the design, fabrication, and analysis of a board level free space interconnect system based on holographic optical elements. The interconnect scheme is implemented in a prototype with four fully interconnected transceiver modules. The design and fabrication procedure for the holographic optical elements is presented in detail. The impact of the electro-optical and electronic components on the system is analyzed and the performance of the integrated system is presented. Alternate components for future development such as diffractive binary lens arrays are discussed.

A decrease in the size and weight of the objective lens in an optical data storage system (ODS) would improve performance. Limits on reducing the lens size were investigated. Size reduction is limited by aberrations introduced by the disk cover plate that protects the recording medium from dust and scratches. Size reduction is also limited by off-axis aberrations introduced by beam tilt required to maintain a field of view similar to conventional ODS objectives. It was shown that a Fresnel microlens on a thin spherical shell is acomatic for all field angles. A technique used to fabricate such a lens was demonstrated. The resulting lens was presented.

Far infrared transmission properties of metallic and insulating granular free standing $\rm YBa\sb2Cu\sb3O\sb{x}$ thin films were measured. Since no substrate was present, we were able to cover a 10-650 cm$\sp{-1}$ frequency range, wider than in any previous transmission measurements on these materials. The films, prepared by a novel technique, were 0.1-1 $\mu$m thick and about 100 mm$\sp2$ in area. This is compared to the 1 mm$\sp2$ area of free standing films made by previous methods. The metallic films showed the superconducting transition below 85 K. All of the films had the stoichiometric composition and the expected polycrystalline lines in the x-ray spectra. / The transmission spectra of the metallic films were measured both in the normal and the superconducting states. These films behaved as a mixture of conducting and insulating small grains in the vicinity of the percolation threshold. The data were modeled by the two-dimensional effective-medium approximation. The calculated frequency-dependent absorption coefficients and the effective conductivities agreed with some previous theoretical studies. This experiment is the first investigation of percolative phenomena in an insulator-high-T$\sb{\rm c}$-superconductor mixture. / We also measured the reflectance spectra of modified Heusler alloys, UNiSn and ThNiSn, at temperatures 10-300 K in the frequency range 10-700 cm$\sp{-1},$ and at room temperature in the range 10-44800 cm$\sp{-1}.$ These are the first measurements on these materials in this frequency range. The reflectance spectra are consistent with the semiconducting behavior of ThNiSn, and the observed metal-semiconducting transition in the UNiSn system at 43 K. Below 42 K UNiSn orders antiferromagnetically, while the isostructural ThNiSn shows no such ordering. Two phonon lines, observed in the UNiSn spectra, split below 42 K, indicating a lattice change. A single phonon line was present in ThNiSn spectra at all temperatures. The dielectric functions and conductivities were calculated from the reflectance spectra using the Kramers-Kronig analysis. Below 42 K we observed an antiferromagnetic mode at 20 cm$\sp{-1}$ in the UNiSn sample. / Source: Dissertation Abstracts International, Volume: 53-07, Section: B, page: 3567. / Major Professor: Hon-Kie Ng. / Thesis (Ph.D.)--The Florida State University, 1992.

<p>Worldwide there are significant efforts to build networks that can distribute photonic entanglement, first with applications in communication, with a long-term vision of constructing fully connected quantum processing networks (QPN). We have constructed a network of atom-light interfaces, providing a scalable QPN platform by creating connected room-temperature qubit memories using dark-state polaritons (DSPs). Furthermore, we combined ideas from two leading elements of quantum information namely collective enhancement effects of atomic ensembles and Cavity-QED to create a unique network element that can add quantum processing abilities to this network. We built a dual connection node consisting of two moderate finesse Fabry-Perot cavities. The cavities are configured to form a cross-cavity layout and coupled to a cold atomic ensemble. The physical regime of interest is the non-limiting case between (i) low N with high cooperativity and (ii) free-space-high-N ensembles. Lastly, we have explored how to use light-matter interfaces to implement an analog simulator of relativistic quantum particles following Dirac and Jackiw-Rebbi model Hamiltonians. Combining this development with the cross-cavity node provides a pathway towards quantum simulation of more complex phenomena involving interacting many quantum relativistic particles.

The primary aim of this study is to understand the general features of thermal impact of carbon dioxide laser with tissue. Because of high water content in tissue one expects that the thermal parameters of water are close to those of tissue. Accordingly, measurements of crater dimensions and temperature distribution in irradiated tissue are compared with values calculated from a theoretical 'water' model of tissue. The thermal parameters of water are found to be similar to those of tissue Few studies of basic carbon dioxide laser interaction with crater effects included have been carried out in the past. In this work crater volume, depth, diameters with different laser power, exposure time have been measured. Temperature history at different positions around crater have been measured and compared with calculated values. We find they are in qualitative agreement. The result may be understood within the framework of energy conservation and heat conduction The measurements are compared with the results of computer modeling of the process. The model cotreats the effect of convection heat loss on surface, the heat conduction percentage, and determines which variables (laser power, exposure time, and spot size) most strongly contribute to the temperature history, maximum temperature, and other features of interest / acase@tulane.edu

non disponible

Cette thèse s'articule autour de la question suivante : comment la complexité d‟un milieu peut elle être exploitée pour contrôler la propagation d‟ondes ultrasonores ? Dans une première partie, les performances d‟une nouvelle technique de focalisation (focalisation par contrôle de front d‟ondes) sont comparées expérimentalement et théoriquement à celles de la focalisation par retournement temporel dans des milieux multidiffuseurs. Il est alors mis en évidence qu‟à condition d‟optimiser à la fois la phase et l‟amplitude de l‟onde nous pouvons réaliser parfaitement un filtre adapté avec une simple mesure de l‟énergie au point focal. Dans une seconde partie, le régime de localisation transverse est exploité pour guider une onde tout en limitant sa dispersion temporelle. Le long d‟une collection de diffuseurs cylindriques distribués aléatoirement dans le plan transverse, un faisceau ultrasonore est confiné sur un diamètre inférieur au diamètre de l‟échantillon. La dernière partie est consacrée à la conception et à l‟étude de la propagation ultrasonore dans des milieux contrôlés constitués de bulles d‟air. Il est montré que les propriétés de ces milieux empruntent à la fois aux métamatériaux et aux cristaux phononiques. Ces nouveaux matériaux sont conçus de manière à obtenir des bandes interdites qui exploitent à la fois les résonances des bulles (" gap d‟hybridation ") et leur répartition périodique (" gap de Bragg "). Au-delà de leurs applications possibles au filtrage acoustique, ces résultats sont intéressants pour clarifier les rôles respectifs de l‟hybridation des résonances et des effets de réseau dans les propriétés des matériaux contenant des diffuseurs résonants.

Voir conclusion générale en fin de pdf (3 pages).

Voir conclusion et travaux futurs p. 167 du pdf

Voir éventuellement l'introduction en page 2 du pdf