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 159 for “"Physics, Optics"”.
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Coherent optical nonlinearities in semiconductor microstructures
This dissertation presents investigations of fundamental optical nonlinearities in semi-conductor microstructures. Two distinct effects are studied. In the first part the excitonic optical Stark effect in InGaAs and GaAs multiple quantum-well structures is investigated by means of pump-probe …
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Stabilization of an FM active harmonic mode-locked fiber laser at high repetition rates
A new and simple approach was optimized for stabilizing a harmonic active mode-locked fiber laser at 40GHz. A computer tunes the modulation frequency in a 500kHz band near 40GHz to follow variations in the optical cavity length. A second approach based on a Proportional-Integral ( PI) controller …
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Theory and fabrication of colloidal-crystal Bragg filters
A theory, based on material parameters, is developed for colloidal-crystal Bragg filters. The coupling constant, for coupled-wave equations, is derived to produce filter spectra. The spectra are modified by convolving with a Gaussian function to represent crystal defects. Scattering losses are …
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Optical engineering of parallel optical data storage
Volume holographic data storage uses the superposition of image holograms in a suitable medium to pursue large storage capacity and high readout rates. The holographic method of structuring the medium with data, and subsequent readout of those data structures, relies on an optical system with two …
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Laser diode-to-singlemode fiber butt-coupling and extremely-short-external-cavity laser diodes: Analysis, realization and applications
The butt-coupling of a Fabry-Perot semiconductor laser diode and a singlemode optical fiber was realized and characterized in the near field. A novel butt-coupling model was developed and found very effective in describing all physical phenomena that occur when the butt-coupling parameters are …
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Explanation and prediction of curious experimental phenomena in lasers and nonlinear optics
Experimental data often contains curious and unexplained results. In the course of experimental investigations of Raman shifting and the Co:MgF₂ laser, results were obtained which would not have been expected from the typical theoretical picture. In the case of Raman shifting, the forward Stokes …
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The Microphysical and Radiative Properties of Tropical Cirrus From the 2006 Tropical Warm Pool International Cloud Experiment (twp-Ice)
The impacts of variations in small ice crystal shapes and concentrations on bulk scattering properties of tropical cirrus are quantified. The calculated mean asymmetry parameter g¯ for the fresh anvil (i.e., 2 Feb) is larger than that for cirrus bands of varying ages (i.e., 27 and 29 Jan.) for …
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Tissue Blood Flow and Oxygen Consumption Measured With Near -Infrared Frequency -Domain Spectroscopy
This research gives a solid background towards a ready-to-use instrument that can continuously, in real-time, measure blood parameters and especially blood oxygenation. This is a very important information in emergency medicine, for persons under intensive care, or undergoing surgery, organ …
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Fluorescence Imaging With One Nanometer Accuracy: Determination of How Processive Motors Walk
"Cargo transportation within a cell is accomplished by processive molecular motors. Motor proteins haul the cargo and transport it over long distances by taking hundreds of consecutive steps without dissociating from the cytoskeleton. Myosin V, myosin VI, and kinesin are well known processive …
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Quantitative Multispectral Biosensing and Imaging Using Plasmonic Crystals
… of the crystals, and to provide insight into the physics underlying the complex optical response of these novel plasmonic structures.
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Optical Metamaterials: Design, Characterization and Applications
"I also demonstrate progress made in ""superlensing"", a phenomenon associated with plasmonic metamaterials, leading to subdiffraction resolution with optical imaging. Fabricating a smooth silver superlens (0.6nm root mean square roughness) with 15nm thickness, I demonstrate 30nm imaging resolution …
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A Dual-Pump CARS System for the Simultaneous Detection of Nitrogen and Methane
Single-laser-shot CARS spectra of nitrogen and methane were obtained from the cylinder of a firing DING engine. Histograms of the integrated intensity ratio from these measurements show a broad distribution of methane concentrations.
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Investigation of Degenerate Four -Wave Mixing and Polarization Spectroscopy for Quantitative Measurements in Combustion Environments
The application of DFWM and PS for quantitative concentration measurements was investigated experimentally by measuring lineshapes and signal intensities in well-characterized hydrogen/air flames. Resonances in the A2Sigma +-X2pi (0,0) band of hydroxyl (OH) were probed with both perturbative and …
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Fabrication Techniques and Modeling for Unusual Optical Systems: Near Field Phase Shift Lithography and Plasmonic Sensors
A second dissertation topic involved exploring the field of nano-plasmonics, with a strong emphasis on sensing applications. Until recently, the development of this field has suffered from difficulties and high cost associated to the production of high quality samples. Soft lithographic techniques, …
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Synthesis and Characterization of Functional Mesostructures Using Colloidal Crystal Templating
Functional 3-D periodic mesostructures were synthesized via colloidal crystal templating, and their chemical, physical, and optical properties were characterized. By forming colloidal crystals through self-organization, infiltrating the interstitial space with functional materials, and removing the …
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Proximity Field Nanopatterning, Its Optics and Applications
New techniques for three dimensional (3D) nanopatterning have been an active field of research to comply demanding complex structures and nanoscale sizes of proposed ideas and potential applications; conventional photolithography and other nanopatterning methods are useful for some of them, still, …
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Numerical Simulation of Vertical Cavity Surface Emitting Lasers
… simulation of VCSEL devices. The fundamental physics of VCSELs are no different from the physics of other semiconductor lasers; however, the approximation of a closed boundary imposed on the optical modes by Minilase is no longer acceptable. Therefore, the extension of Minilase primarily …
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A Comprehensive Study of Hybrid Vertical -Cavity Surface -Emitting Lasers
The high frequency modulation response for hybrid VCSELs is measured and compared to the theoretical response of the VCSEL derived through small signal analysis, with good agreement. For the two single mode structure wafers measured, the VCSELs with the implant aperture located farther away from …
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Vertical -Cavity Surface -Emitting Lasers Operating in Photonic Crystal Waveguide Defect Modes
Single mode operation in vertical cavity surface-emitting lasers is important for sensing and communications applications. A comprehensive study of the use of a periodic array of etched circular holes in the top distributed Bragg reflector of a vertical cavity surface-emitting laser to achieve …
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Slow Light Based on Quantum Effects in Quantum Wells and Quantum Dots
This is a detailed study of slow light based on quantum effects in semiconductor nanostructures. We propose to implement an optical buffer using semiconductor quantum dots and quantum wells based on coherent population oscillation and spin related electromagnetically induced transparency. We …
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