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 40 for “"Optical Control"”.
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Optical Control over Nuclear Spins
… opportunities in the applications of optical approaches. In condensed matter physics/materials science, optical approaches provide great flexibility in characterizing material properties, driving excitations, and even triggering phase transitions in materials. Meanwhile, light-matter …
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Quantum spins in semiconductor nanostructures: Hyperfine interactions and optical control
… contributions, including protocols for the control of the spin and a scheme for the generation of entangled photon states from coupled quantum dots, will be presented. We then look at the interaction between the electron and the surrounding nuclear spins and describe how its interplay with …
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Optical control of polariton condensation and dipolaritons in coupled quantum wells
… on simulation of polariton condensates. The optical setup and the microcavity sample are presented thereafter, including holographic laser shaping with a spatial light modulator (SLM), which allows exciting the microcavity with arbitrarily shaped pump geometries. Experimental results comprise …
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Optical Control and Spectroscopic Studies of Collisional Population Transfer in Molecular Electronic States
… characters of the \textit{gateway} levels can be controlled by manipulating the coupling laser \textit{E} field amplitude. We observe experimentally the collisional population transfer between electronic states $G^1\Pi_g (v=12, J=21, f)$ and $1^3\Sigma _g^-(v=1, N=21, f)$ of $^7$Li$_2$. We obtain …
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Microwave and optical control of sub-diffraction spin qubits in diamond at cryogenic temperatures
Efficient entanglement of negative nitrogen vacancy (NV) centers in diamond will bring us significantly closer to realizing a large scale quantum network, including the design and development of quantum computers. A central requirement for generating large-scale entanglement is a system that can be …
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Defects and Ionic Transport at Reduced Temperatures -- Electric Field and Optical Control on Nanoscopic Spatial Scales
The ability to study and control oxygen ion transport in metal oxide systems at reduced temperatures (<400°C) is key to the design of new generations of energy conversion/storage, memory and functional device applications, but has remained a significant challenge in the field of Solid-State Ionics. …
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Optical control and probe of ferromagnetic and ferroic orders in films, heterostructures, and perovskite-based material systems
… organic-inorganic perovskites. Low-power all-optical memory offers a unique opportunity to achieve ultra-fast magnetic switching in which the switching dynamics are not thermally mediated and occur on the order of the laser pulse. However, it is challenging to achieve a low-power optically …
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Probing the Ultrafast Dynamics of Higher-Lying Excited States of Molecular Switches with Femtosecond Stimulated Raman Spectroscopy
… states have shown to play a critical role in the optical control of reaction dynamics and product yield of many photoactive molecular systems. However, due to their short lifetimes and high density of states, the initial dynamics and molecular motions within the upper states is less understood. In …
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Design, implementation and control of a sparse aperture imaging satellite
… The MIT Adaptive Reconnaissance Golay- 3 Optical Satellite (ARGOS) project exploits wide-angle Fizeau interferometer technology with an emphasis on modularity in the optics and spacecraft subsystems. Unique design procedures encompassing the nature of coherent wavefront sensing, control …
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Staged attitude-metrology pointing control and parametric integrated modeling for space-based optical systems
… The first technology is precision pointing control technology, which can provide fine optical control operating in conjunction with coarse formation flying attitude control in order to meet the stringent optical requirements. This will potentially enable a long baseline Formation Flying …
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Design and shape control of lightweight mirrors for dynamic performance and athermalization
… segmented or sparse apertures and active optical control. Many of these technologies have no flight heritage, so determining what combinations of technologies will create favorable designs requires detailed modeling and analysis. This thesis examines the design of a lightweight mirror for …
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Controlling and Understanding Atomic-Scale Dynamics within Plasmonic Nanogaps
… confine light to nanoscale volumes and enhance optical fields by orders of magnitude. This enhancement allows a few hundred molecules placed in this gap, such as biphenyl-4-thiol, to be probed by techniques like surface-enhanced Raman spectroscopy (SERS). In addition, the enhanced fields induce …
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Quantum State Singlet-Triplet Character Control in 7Li2
We have demonstrated a means of quantum control by all-optical control of valence electron spin polarization in the lithium dimer. The energy levels of interest are two closely spaced rovibrational levels (the G1Πg (12, 21f) and 13Sg- (1, 21f) states separated by 720 MHz). In the absence of any …
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Characterization and connectorization of optoelectronic neural probes
… systems. Furthermore, recent advances in optical neural stimulation methods would benefit from seamless integration of optical waveguides into neural probes. In this thesis, we describe electronic and optical characterization of polymer-based probes produced through thermal drawing …
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Two-dimensional ultrafast pulse shaping and its application to coherent control and spectroscopy
… and explores their application to coherent control of propagating lattice excitations and degenerate four-wave mixing spectroscopy. Pulse shaping in two dimensions is achieved by manipulating the spectral components of ultrashort laser pulses within many horizontal slices of the pulse. Each …
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Integrated modeling of optical performance for the Terrestrial Planet Finder structurally connected interferometer
… tools known as DOCS (Disturbances Optics Controls Structures) that provides a MATLAB environment for managing integrated models and performing analysis and design optimization. DOCS provides a framework for identifying critical subsystem design parameters and efficiently computing system …
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Collective charged particle dynamics in relativistically transparent laser-plasma interactions
… transparency is an important step towards optical control of charged particle dynamics in laser driven dense plasma sources and in its potential applications; including ion and radiation source development.The experimental and numerical investigations exploring the onset and the …
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Exciton-polaritons in thermal equilibrium : from Bose-Einstein condensation to exciton-polaritonics
Coherent control has been at the heart of the study of physical chemistry. Great advancement has been achieved in the past few decades in coherent control of classical systems by using spatially and temporally shaped electromagnetic waves. In this dissertation, we extend the concept of coherent …
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Fast star tracker centroid algorithm for high performance CubeSat with air bearing validation
… of arcseconds. ExoplanetSat uses dual stage control to achieve the pointing requirement. Reaction wheels provide coarse satellite attitude control while a high bandwidth piezoelectric stage performs fine optical stabilization. The optical sensor provides star images from which a centroiding …
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Customizing Multifunctional Bidirectional Neural Interfaces through Fiber Drawing
… polymer waveguides for concurrent electrical and optical neuromodulation. To address this challenge, three fabrication approaches based on fiber drawing were introduced. Each method delivered multifunctional probes featuring a low-loss transparent waveguide for optical stimulation, low-impedance …
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