El Sayed, Ali (2019). Optical and spectral characteristics of Yb-doped, Al and P co-doped silica fibers prepared by the sol-gel based granulated silica method. (Dissertation, Institut für Angewandte Physik, Philosophisch-naturwissenschaftliche Fakultät)
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Text (Dissertation)
PhD-Dissertation_El-Sayed.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (18MB) |
Combining the sol-gel method for fiber material production with the granulated silica method for preform assembly results in a robust method that offers a high degree of freedom regarding both the composition and the geometry of the produced fiber. Using this method several Yb-doped silica fibers/glasses have been prepared with varying Al/P and Al/Yb concentration ratios. In this work, the spectral and optical properties of the prepared samples were studied in correlation with their Al and P content. The optical analysis have been carried out on fibers by measuring the elemental distribution of the dopants, the refractive index profiles, fluorescence lifetimes, and laser slope efficiencies. On the other hand, a spectral analysis has been carried out on polished glass disks by recording their absorption and emission characteristics from the UV to the NIR range, in order to reveal the impact of Al and P content on the redox state of Yb ions, on the cooperative process of Yb ion pairs, and on the NIR fluorescence characteristics. All observations in this work point towards significant influence of the Al/P concentration ratio and their absolute content concentration with respect to Yb, on the overall characteristics of an Yb-doped fiber/glass. Among the several prepared samples, favorable laser glass has been achieved with the compositions that feature slight excess in P concentration with respect to Al concentration due to the remarkable role of P in diminishing the formation of Yb2+ ions and enhancing the Yb distribution in the silica network. These results have enabled the optimization of the Al and P content concentration in our Yb-doped silica fibers, leading to a fiber that features a laser slope efficiency of 67% at around 1030 nm.
Item Type: |
Thesis (Dissertation) |
|---|---|
Division/Institute: |
08 Faculty of Science > Institute of Applied Physics |
UniBE Contributor: |
El Sayed, Ali |
Subjects: |
500 Science 500 Science > 530 Physics 600 Technology > 620 Engineering |
Language: |
English |
Submitter: |
Valerio Romano |
Date Deposited: |
11 Sep 2020 14:16 |
Last Modified: |
05 Dec 2022 15:40 |
BORIS DOI: |
10.7892/boris.146476 |
URI: |
https://boris.unibe.ch/id/eprint/146476 |
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