Characterisation of hollow-core photonic bandgap fibres and other multimode fibres for optical communications

Abstract

Progress in multimode fibre technology has opened diverse opportunities in science and technology, one of which is pushing data capacities beyond the fundamental limits of conventional single-mode fibre, so as to avert network gridlock precipitated by exponentially growing global traffic demands. Hollow-core photonic bandgap fibres (HC-PBGFs), where light propagates in air rather than glass, have been considered as a potential candidate for high-capacity telecommunications applications, while offering superior performance over solid-core fibres in terms of low loss, low latency, and ultralow nonlinearity.

This thesis presents research conducted as part of the efforts of the EU FP7 project MODE-GAP to pioneer developments in HC-PBGF and related space-division multiplexing technologies. This work is involved with the characterisation of primarily HC-PBGFs and also solid-core multimode fibres, recently and respectively fabricated through the facilities of the Optoelectronics Research Centre and other project partners. A time-of-flight method is applied to make extensive measurements on these fibres to study their modal properties, including mode coupling and differential modal delay, in order to assess their capabilities for single-mode as well as mode-division multiplexed data transmission. In support of the fibre design process, this work has aided the full characterisation of the first ever fabricated 37-cell HC-PBGFs and enabled subsequent mode-division multiplexing trials at a record capacity of 73.7 Tbit/s. Characterisation of multi-kilometre record-length HC-PBGFs is also performed, and has supported the demonstration of these fibres in metro network environments.

To further understand the modal processes and facilitate fibre improvement, a simulation environment is constructed based on a power coupling propagation model. This has enhanced interpretations of experimental time-of-flight data, as well as validated a proposed theory relating mode coupling and loss in HC-PBGFs.

Finally, an experimental technique is introduced to inspect longitudinal defects in solid- and hollow-core fibres, by applying time-of-flight principles.

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Identifiers

ORCID for Nicholas Heng Loong Wong: orcid.org/0000-0002-1743-3959

ORCID for David Richardson: orcid.org/0000-0002-7751-1058

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