Antiresonant hollow-core optical fibres

Abstract

Antiresonant fibres (ARFs) have a microstructure consisting of a hollow core surrounded by a cladding formed of thin webs of glass. Unlike conventional optical fibres which guide light in solid glass, light propagates through the hollow core of ARFs, allowing them to guide light without the limitations imposed by the optical properties of the glass that forms them. ARFs are therefore capable of guiding light with a lower latency, higher damage threshold, lower nonlinearity and lower transmission loss than conventional fibres. Great strides have been made over the past decade in improving the optical properties of ARFs. However, there is still not a comprehensive model describing their guidance, and only a fraction of the possible ARF microstructures have been explored. In order to continue improving ARFs, there must be a comprehensive understanding of how they guide light, and their fabrication must be developed further.

The research presented in this thesis describes the development of a new fabrication methodology, the use of simulations to explore the properties of novel ARFs, and the application of the fabrication method to fabricate the ARFs that were simulated. The fabrication of these fibres is described in detail, and the properties of the fibres which can be exploited in order to realise low loss guidance are discussed. It is demonstrated through simulation that hollow glass structures in the cladding of an ARF can reduce its loss, and elongating the cladding in the radial plane can reduce the loss further. Two novel ARFs are fabricated which exploit these features, and their fabrication and optical properties are described. A new one-dimensional model is presented and used to simulate the effect of incorporating ultra-thin additional azimuthal glass layers within ARF cladding resonators. It is shown that the additional glass layers impact the mode order of the fundamental-like core guided mode, which influences the leakage loss of light through the resonators.

Date of Award	24 May 2023
Original language	English
Awarding Institution	University of Bath
Supervisor	James Stone (Supervisor) & Tim Birks (Supervisor)