Nonlinear optical phenomena in fluoride glass and hybrid fibres

• Main Author: Fischbach, Stefan
• Other Authors: Da Como, Enrico
• Published: University of Bath 2017
• Subjects: 621.36
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715304

This thesis investigates nonlinear optical phenomena in non-silica fibres, in a first part utilising a fluoride fibre, followed by the exploration of hybrid fibres with an organic single crystal inside a fibre capillary. The unique properties of 55ZrF4, 18BaF2, 6LaF3, 4AlF3, 17NaF (ZBLAN) glass allow the creation of optical fibres with a highly extended transmission window on the longer wavelength side. We investigated the properties of ZBLAN fibres in order to optimise supercontinuum (SC) generation in a ZBLAN fibre pumped by an optic parametric amplifier. To study applications of the ZBLAN SC we integrated the SC into a pump-probe setup, being used as a near-infrared broadband probe source. We have carried out proof-of-principle measurements on an organic copolymer thin-film, showing the possibility of utilising a ZBLAN SC, allowing to extend the usability of broadband sources to the nearand mid-infrared, while simplifying the usage of the setup. The second part of this thesis explores the possibilities of hybrid fibres by using a hollow-core silica capillary with an organic single-crystal inside. We have developed and optimised a method to grow an organic semiconducting crystal inside a hollow core capillary based on the Bridgman-technique. We could demonstrate the filling of the inner capillary for diameters down to 1 m and with different materials based on the anthracene structure, opening up possibilities for various hybrid fibres. The quality of the single-crystals was evaluated by micro-Raman and X-ray diffraction measurements. We could access nonlinear properties of the crystal by coupling light with an energy lower than the band-gap into the fibre. Stimulated by two-photon absorption photo-luminescence from the fibre core was observed for the hybrid fibre. The results obtained for the hybrid fibres gives rise to a vast amount of possibilities for different hybrid fibres with tailored optical properties of organic materials and their optimisation in the guiding of light.