Abstract
Inspired by spatially varying refractive index profiles within the lens in human eyes which can mitigate chromatic aberration and allow high-resolution imaging, we aim to develop a scalable approach for manufacturing high-precision three-dimensional (3-D) gradient refractive index (GRIN) nanocomposites based on multi-component bulk Ge-As-Pb-Se (GAP-Se) glass-ceramics for their use in infrared imaging systems. This work extends our efforts towards optimizing processing protocols for nominally single-phase parent bulk glasses where we specifically attempt to address prior challenges associated with nano/micro-scale liquid-liquid phase separation of the as-formed bulk material. Key findings of this work illustrate new understanding of the process beyond prior efforts. Firstly, this process illustrates improvements to the glass' homogeneity over prior lab-scale melt-quenched melts due to the physical dispersion of Pb within the glass matrix. Secondly, the laser induced Pb-rich amorphous phase by a near-bandgap 2 μm laser, upon subsequent heat treatment undergoes crystallization resulting in the formation of high-index PbSe containing nanocrystals, that results in effective refractive index modification. Thirdly, while the desired high index PbSe containing phases resulted from the protocols developed, other crystal phases that reduce spatial resolution and induce unacceptable levels of scatter loss remain. Despite this drawback, losses in the glass as a function of base material depth were sufficiently low to allow creation of axial modification of the irradiated glass for the first time. While measurement of effective refractive index is not possible with our experimental instrumentation, the axial variation in crystal fractions with laser dose has been demonstrated, suggesting a corresponding axial gradation in the bulk material's refractive index. The degree of crystallinity in the glass-ceramic yielding effective refractive index changes has been shown to be modulated by the laser dose, providing a route towards spatially tailorable index change and modification to the composite's dispersion.
Notes
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Graduation Date
2023
Semester
Summer
Advisor
Richardson, Kathleen
Degree
Master of Science (M.S.)
College
College of Optics and Photonics
Department
Optics and Photonics
Degree Program
Optics and Photonics
Identifier
CFE0009901; DP0028434
URL
https://purls.library.ucf.edu/go/DP0028434
Language
English
Release Date
February 2027
Length of Campus-only Access
3 years
Access Status
Masters Thesis (Campus-only Access)
STARS Citation
Zachariou, Anna, "Creation of Three-Dimensional Gradient Refractive Index Profiles in Bulk Ge-As-Pb-Se Glasses" (2023). Electronic Theses and Dissertations, 2020-2023. 1930.
https://stars.library.ucf.edu/etd2020/1930
Restricted to the UCF community until February 2027; it will then be open access.