Manufacturing high purity chalcogenides

Abstract

Interest in infrared fibres has grown immensely as niche applications arise as a replacement for silica based optical fibres, whose properties limit its use in the mid infrared. Some of these applications include laser power delivery, chemical sensing and imaging. Of the many infrared transparent materials, the focus of this thesis in particular, will be on high purity chalcogenide glass. While great strides have been made in reducing optical losses of chalcogenides, further improvements are needed in both synthesis and fibre drawing techniques to attain its theoretically predicted potential.

In this thesis, glass making techniques including sealed ampoule, levitation, chemical vapour deposition and reactive atmosphere processing techniques are developed and evaluated for producing high purity chalcogenide glass. A state of the art reactive atmosphere processing system with high purity gas delivery of five gasses; argon, hydrogen sulphide, hydrogen, oxygen and chlorine is implemented. The system is automated using National Instrument hardware and Labview software which allows monitoring and data logging in real-time. This bespoke automated system to make chalcogenide has led to reduction in losses to less than 1dB per metre in the 3 to 5 µm region in bulk glass. Experiments and improvements to chemical vapour deposition facilities were done with the goals of scaling the method from thin film deposition to producing high purity bulk glass and fibre. Limits to this process have not been overcome and the challenges remaining are detailed within this thesis. However, new concepts have been developed for implementing a CVD to fibre fabrication process and initial results are presented.

The results of this thesis show significant improvement in glass synthesis facilities at the Optoelectronics Research Centre, greatly facilitating production of next generation ultra-low loss chalcogenide glass and fibre.

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ORCID for Daniel Hewak: orcid.org/0000-0002-2093-5773

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