Hänzi, Pascal (2024). Laser-assisted Fabrication of Specialty Optical Fibers and Applications in Nonlinear Optics, Light Amplification, and Sensing. (Thesis). Universität Bern, Bern
|
Text
24haenzi_p.pdf - Thesis Available under License Creative Commons: Attribution (CC-BY 4.0). Download (99MB) | Preview |
Abstract
The demand for specialty optical fibers is ever growing. Requirements range from engineered dispersion to managed nonlinearity to optimized gain profiles. Conventional chemical vapor deposition (CVD) techniques are optimized for kilometer-scale fiber production and are relatively inflexible and cost ineffective for rapid fiber prototyping. A fast turnover rate from design to product is essential for unique doping compositions, such as high amounts of individual rare earths, a mixture of several, or more temperature sensitive dopants such as nanoparticles. To overcome these limitations, a novel preform fabrication technique based on CO2 laser vitrification has been developed. The result is two different approaches to doping silica fibers, powder-in-tube laser vitrification (PLV) and liquid-layer laser vitrification (3LV). The PLV enabled the successful incorporation of nanodiamond particles into silica fibers. Measurements show a highly dispersive nonlinearity, while the chromatic dispersion remains largely unchanged, demonstrating the potential for independent nonlinearity and dispersion engineering. 3LV was found to be effective in producing homogeneously doped rare earth fibers, resulting in highly ytterbium-doped fibers with performance comparable to commercial fibers, validating the capability of the new method to produce high quality doped glass material. Leveraging the flexibility of both methods, multiple rare earth doped fibers were developed that exhibit fluorescence emission over a full octave. In addition, the fabrication of an alumina core fiber with a high rare earth concentration was investigated with the possibility of short amplifiers, high thermal loads, and mid-IR operation in mind. Similar fibers doped with terbium were fabricated and tested for Faraday rotation, useful in magnetic field and current sensing applications. Finally, noise sources in supercontinuum (SC) generation are investigated, leading to the development of a hybrid dispersion fiber that utilizes anomalous dispersion for initial pulse compression and all-normal dispersion for nonlinear pulse broadening. The generated SC exhibits ultra-low noise while spanning more than a full frequency octave. This approach is easily adaptable and can potentially improve the performance and noise characteristics of other photonic systems such as optical frequency combs (OFCs).
| Item Type: | Thesis |
|---|---|
| Dissertation Type: | Cumulative |
| Date of Defense: | 26 September 2024 |
| Subjects: | 500 Science > 530 Physics 600 Technology > 620 Engineering |
| Institute / Center: | 08 Faculty of Science > Institute of Applied Physics |
| Depositing User: | Hammer Igor |
| Date Deposited: | 12 Dec 2024 07:16 |
| Last Modified: | 12 Dec 2024 07:16 |
| URI: | https://boristheses.unibe.ch/id/eprint/5675 |
Actions (login required)
 |
View Item |