Liquid filled waveguides and fibres

Thesis

Ever since the initial development of fibre Bragg gratings (FBGs) in 1977, their inherent sensitivity to both temperature and strain has become a significant challenge. This thesis seeks to address this enduring issue by developing novel FBG devices that would potentially solve this 47-year-old problem.

Through the exploration of a novel approach using liquid-filled waveguides and fibres, detailed insights into its implementation across design, fabrication, and experimental demonstration are provided. A thorough examination and comparison of various analysis and simulation techniques are undertaken to provide detailed guidelines for device designs. A distinctive technique of aberration correction was introduced to focus the laser beam into the optical fibres during fabrication. This enables the fabrication of micro-engineered FBG devices with fluid-filled microchannels within the evanescent fields. These devices provide extraordinary thermal sensitivities and the significant achievements in these devices effectively meet the requirements of various optical devices and optical fibre sensing applications. This research contributes to the field by offering a comprehensive solution to a longstanding problem in FBG sensor technology. Through a series of experiments and simulations, the feasibility and effectiveness of this approach are demonstrated. Furthermore, the thesis explores methods for reinforcing FBG devices for strain sensing, including recoating with polymers and custom fibre designs. These methods enhance the mechanical strength of FBG devices, improving their durability and reliability in sensing applications.

Overall, this thesis presents a significant advancement in FBG sensor technology, offering a comprehensive solution to the longstanding challenge of strain and temperature discrimination. The research conducted contributes to the understanding of FBG sensor technology and provides practical solutions that have the potential to impact a wide range of optical sensing applications.

Authors: Song, Z

• DOI: 10.5287/ora-zbyayxjzp
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: optical waveguides; microchannel fibers; temperature compensation; ultrasensitive sensors; temperature and strain discrimination; fiber Bragg gratings
• Subjects: Optical wave guides; Optical detectors; Micro-drilling; Fiber optics