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

Language

English

Release Date

February 2027

Length of Campus-only Access

3 years

Access Status

Masters Thesis (Campus-only Access)

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Restricted to the UCF community until February 2027; it will then be open access.

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