Development of fibre optic measurement for specialty optical fibres

• Main Author: Ter, Nigel Guohong
• Other Authors: School of Electrical and Electronic Engineering
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
• Online Access: http://hdl.handle.net/10356/61497
• Institution: Nanyang Technological University

In recent years, high-power fibre lasers have been replacing other types of lasers in a number of metal processing processes such as welding, cutting, cleaning, marking and embossing. With increasing demand on the enhancement of these new fibre lasers, the development of new specialty fibres has become a hot topic. Yet, methods of measuring these specialty optical fibres remain largely uncharted. In this Final Year Project, various methods of characterizing optical fibres, namely Encircled Flux, Beam Profile, Insertion Loss, Optical Path Length and Effective Refractive Index Difference, were explored, and their suitability discussed. In addition, different techniques such as measuring coupling efficiency against lateral offset as well as using a single photodetector to measure the Optical Path Length were also examined. It was discovered that Insertion Loss due to different connector types is minimal and different light sources yielded different results, whereas to measure Optical Path Length, the single-photodetector single-channel method was heavily dependent on the capabilities of the oscilloscopes used. Finally, knowledge gleaned from these procedures was applied to the investigation of a few-mode specialty fibre with as yet unknown characteristics. Parts of the results have been incorporated into two papers accepted by the 2014 NEWRAD conference. In summary, this project hopes to help define new standards while developing measurements for specialty optical fibres.