Munch, JesperMonro, Tanya MaryBoyd, Keiron2014-10-162014-10-162013http://hdl.handle.net/2440/86275This thesis presents an investigation into the direct CO₂ laser post processing of optical fibres, with a specific emphasis on soft glass compositions. It presents novel techniques for the fabrication of soft glass optical fibre based devices, novel techniques for the direct measurement of glass melt properties and the optical characterization of all fabricated devices, including a novel technique for measuring the evolution of ultra-short pulses along sub-wavelength tapered optical fibre. New photonic devices fabricated from soft glass optical fibres are of scientific interest due to the high non-linearity and high refractive index. However for the increased understanding and controlled fabrication of such devices, measured values of the physical properties of the glass melts are required, and for many new materials this information is either unavailable or must be obtained for the exact conditions that the devices are produced. This thesis presents new methods for the measurement of surface tension and viscosity at the same conditions as the fabrication of the optical devices presented, through the use of a scanning CO₂ laser. It also reports previously unpublished surface tension values for several glass compositions and investigates the effect the glass making environment had on the resulting surface tensions. Novel fabrication techniques for new soft glass optical devices are also presented, including the pressurised tapering of Bismuth MOF using an elliptical CO₂ laser beam control the rate of microstructure collapse or expansion such as to produce a photonic crystal device whereby the zero dispersion wavelength varies as a function of displacement along the taper length. The direct CO₂ laser tapering of silica and soft glass optical fibres to sub-wavelength diameters is also presented as well as the production of new high Q factor optical microsphere’s resonators of diameters <10μm, fabricated from Er-Yb co-doped tellurite glass, and attached to tapers situated near the un-tapered optical fibre for mechanical stability.optical fibre; femtosecond; nanowire; taper; supercontinuum; surface tension; CO₂ laserThesis20141010094805