Development of novel mid-infrared optical fibres

Abstract

The last decades have seen a steady progress in what mid-Infrared (mid-IR) technology can offer to medical, industrial, sensing, environmental and military applications. Remote thermal imaging and fibrerised mid-IR laser delivery are two applications for which special optical fibres that are flexible, sufficiently low loss and robust would be needed. Despite considerable work in the area, no such a solution exists yet that meets all the requirements. In this thesis, the design, fabrication and characterisation of a fibre bundle for thermal imaging, as well as hollow core antiresonant fibres for mid-IR laser delivery are described. The final fabricated bundle is compact in outer diameter, flexible and allows thermal imaging with good resolution of objects as cold as a human body. Modelling work has also been performed to optimise the structure of the bundle for operation at longer wavelengths where cheap microbolometric thermal cameras work and where cold objects have their maximum infrared emission. The second part of this thesis presents the design and fabrication of tellurite and chalcogenide hollow core antiresonant fibres aimed for the delivery of CO and CO2 lasers radiation (5.4 and 10.6 µm), respectively. Several tellurite fibres with losses lower than 10 dB/m in the mid-IR spectral range, and a few preliminary chalcogenide prototypes have been obtained in the project. Modelling studies conclude the work and illustrate how to decrease the optical losses of both tellurite and chalcogenide hollow core antiresonant fibres.

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Identifiers

ORCID for Andrea Ventura: orcid.org/0000-0002-8658-761X

ORCID for Francesco Poletti: orcid.org/0000-0002-1000-3083

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