Current Search: ceramic crystal lasers (x)
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- Title
- Distribution of Laser Induced Heating in Multi-Component Chalcogenide Glass and its Associated Effects.
- Creator
-
Sisken, Laura, Richardson, Kathleen, Richardson, Martin, Shah, Lawrence, University of Central Florida
- Abstract / Description
-
Chalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a...
Show moreChalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a laser, or a combination of photo-thermal interactions. Solely employing laser-based heating has an advantage over a furnace, since one has the potential to be able to spatially modify the materials properties with much greater precision by moving either the beam or the sample.The main properties of ChG glasses investigated in this study were the light-induced and thermally-induced modification of the glass through visible microscopy, white light interferometry, and Raman spectroscopy. Additionally computational models were developed in order to aid in determining what temperature rise should be occurring under the conditions used in experiments.It was seen that ablation, photo-expansion, crystallization, and melting could occur for some of the irradiation conditions that were used. The above bandgap energy simulations appeared to overestimate the maximum temperature that should have been reached in the sample, while the below bandgap energy simulations appeared to underestimate the maximum temperature that should have been reached in the sample. Ultimately, this work produces the ground work to be able to predict and control dose, and therefore heating, to induce localized crystallization and phase change.
Show less - Date Issued
- 2014
- Identifier
- CFE0005261, ucf:50606
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005261
- Title
- OPTICAL AND PHYSICAL PROPERTIES OF CERAMIC CRYSTAL LASER MATERIALS.
- Creator
-
Simmons, Jed, Bass, Michael, University of Central Florida
- Abstract / Description
-
Historically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic...
Show moreHistorically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic crystal using an interferometric method. The interferometer employed a spatially filtered HeNe at 633 nm wavelength. Thermal expansion coefficients measured for the ceramic crystal samples were near the reported values for single crystal Nd:YAG. With a similar experimental setup as that for the thermal expansion measurements, dn/dT for ceramic crystal Nd:YAG was measured and found to be slightly higher than the reported value for single crystal. Depolarization loss due to thermal gradient induced stresses can limit laser performance. As a result this phenomenon was modeled for ceramic crystal materials and compared to single crystals for slab and rod shaped gain media. This was accomplished using COMSOL Multiphysics, and MATLAB. Results indicate a dependence of the depolarization loss on the grain size where the loss decreases with decreased grain size even to the point where lower loss may be expected in ceramic crystals than in single crystal samples when the grain sizes in the ceramic crystal are sufficiently small. Deformation-induced thermal lensing was modeled for a single crystal slab and its relevance to ceramic crystal is discussed. Data indicates the most notable cause of deformation-induced thermal lensing is a consequence of the deformation of the top and bottom surfaces. Also, the strength of the lensing along the thickness is greater than the width and greater than that due to other causes of lensing along the thickness of the slab. Emission spectra, absorption spectra, and fluorescence lifetime were measured for Nd:YAG ceramic crystal and Yb:Lu2O3 ceramic crystal. No apparent inhomogeneous broadening appears to exist in the Nd:YAG ceramic at low concentrations. Concentration and temperature dependence effects on emission spectra were measured and are presented. Laser action in a thin disk of Yb:Y2O3 ceramic crystal was achieved. Pumping was accomplished with a fiber coupled diode laser stack at 938 nm. A slope efficiency of 34% was achieved with maximum output energy of 28.8 mJ/pulse.
Show less - Date Issued
- 2007
- Identifier
- CFE0001764, ucf:47273
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001764