Wire Array Infrared Metamaterial Fibres: Fabrication and Applications

Abstract

Metamaterials are artificial composite materials that exhibit exotic properties due to their components and sub-wavelength structure. During the past decades, several new materials have emerged from this research field with exciting new optical properties and applications. However, the fabrication of certain meta-structures remains a challenge, particularly with low cost and in large volumes. Fibre drawing is an attractive alternative to overcome such problems, but currently fabrication constraints restrict the size of the metal/dielectric drawn structures, limiting their operation to THz frequencies. In this context, this thesis concerns the fabrication, characterization, and use of new soft-glass based wire array metamaterials fibres for applications in the infrared. Numerical modelling of wire array structures is presented to understand which material combinations and structural parameters are more appropriate for infrared metamaterial fibres. The co-drawing process used is described, focusing on the adaptations used to minimize fluctuation of the structure due to fluid dynamics. Metamaterial fibres with uniform structures containing wire diameter and spacing on the order of few hundreds of nm are produced, which are compatible with operation at mid-infrared frequencies. The fabrication of metamaterial fibre tapers with steep transitions, generating hyperlenses, is also demonstrated. Far field imaging is attempted and the challenges regarding subdiffraction imaging are discussed. Feasible alternatives for future far field super-resolution imaging are proposed based on our numerical modelling and the typical structural transitions fabricated. Since the operational range of our hyperlenses is not limited to the infrared, subdiffraction focusing of 1/176 of the operational wavelength is reported at THz frequencies, achieved by combining a polymer hyperlens with our new infrared hyperlens.