Physics Commons^™

Time Domain Measurement Of The Nonlinear Refractive Index In Optical Fibers And Semiconductor Film, Hernando Garcia

Dissertations

A new technique to measure the nonlinear refractive index n₂ in optical fibers and semiconductor films has been developed. It is based on the time delay two-beam coupling of very intense picosecond laser pulses that have been self-phase modulated in the nonlinear optical medium. The two beams are coupled in a slow responding medium that is sensitive to time dependent phase distortions. We determine that the amount of phase distortion experienced by the pulse is proportional to the nonlinear refractive index of the medium, This time domain approach can also be applied to optical fiber amplifiers in the presence …

Modeling, Design And Fabrication Of Thin-Film Microcrystalline Silicon Solar Cells, Wei Chen

Dissertations

The modeling, design and fabrication of low-cost thin-film microcrystalline silicon(µcSi) solar cells is studied in this thesis. The cell, considered in this investigation, utilizes low-cost glass as the substrate and microcrystalline Si (µc-Si) as the active layer. A comprehensive refractive index (n) and extinction coefficient (k) model of silicon as function of doping, temperature and wavelength is developed to assist the optical design of the cell. In order to obtain acceptable short circuit current density (Jsc) from the cell, it is found that the thickness of the silicon thin film should be more than 10µm. To get the best light …

Experimental And Phenomenological Study Of Persistent Photoconductivity In Yba2cu3o6 Thin Films, Daniel-Dennis Mcalevy Bubb

Dissertations

Persistent Photoconductivity in YBa₂Cu₃O_6+x thin films is studied by means of infrared photoconductivity measurements after the films have been illuminated with visible light at low temperature. Experimentally, the effect is characterized by the samples' electrical response to infrared light, either causing the resistance to decrease or increase.

A cellular automata model is proposed in explanation of these results and is shown to be consistent with current experimental understanding of this unusual effect, both our results and those of others. The cellular automata model may have application to other unusual optical phenomena exhibited by YBa_{2 …}