Fiber-Drawn Metamaterial for THz Waveguiding and Imaging

Abstract

In this paper we review the work of our group in fabricating metamaterials for terahertz (THz) applications by fiber drawing. We discuss the fabrication technique and the structures that can be obtained before focusing on two particular applications of terahertz metamaterials, i.e. waveguiding and sub-diffraction imaging. We show the experimental demonstration of THz radiation guidance through hollow core waveguides with metamaterial cladding, where substantial improvements were realised compared to conventional hollow core waveguides, such as reduction of size, greater flexibility, increased single mode operating regime and guiding due to magnetic and electric resonances. We also report recent and new experimental work on near-and far-field THz imaging using wire array metamaterials that are capable of resolving features as small as λ/28.

Terahertz orbital angular momentum modes with flexible twisted hollow core antiresonant fiber

“…A variety of types of hollow waveguides have been studied for THz, which may be separated into metallic, dielectric and hybrid waveguides (including metamaterial waveguides). 3,4,5,6,7,8,9 Metallic hollow waveguides can have subwavelength cross-section and have relatively low loss. Those characteristics arguably make them the current best option for THz waveguides.…”

“…Metamaterial hollow waveguides offer the potential for control of the radiation, 5 can be subwavelength 6 and potentially low loss. 7 However, both complexity of fabrication and the relative lack of research in this field leaves doubts about their real potential. Dielectric THz hollow waveguides are the scaled version of their more successful optical counterpart and have been investigated in the form of Kagome structures, 10,11 simple capillaries, 12 antiresonant structures, 13 and several other variations.…”

Tunable metamaterials fabricated by fiber drawing

“…The holes in the preform are filled with a metal with a sufficiently low melting temperature that it is molten at the polymer drawing temperature. The structure is then drawn such that the polymer is still highly viscous and the liquid metal takes the form of the holes which reduce in diameter during drawing [11][12]. Figure 1 shows a schematic of a typical wire array metamaterial considered here.…”

“…Whilst fabrication of such structures of dissimilar materials on sub-wavelength scales is challenging, there have been numerous demonstrations [7], although few are scalable [8][9][10]. We have successfully fabricated metamaterials in volume by combining two scalable and well-established techniques: fiber drawing and the Taylor wire process [10][11][12].…”

Thermal poling of multi-wire array optical fiber

“…As fibers can accommodate more holes and thus, more electrodes, it is interesting to explore how far this thermal poling can be extended from just two anodes, and the extent to which an induced SON can be distributed through the volume of the glass. Such fibers are available due to recent advances in using fiber drawing for fabricating metamaterials with arrays of tens to hundreds of metal wires [10][11][12][13]. Poling these structures and inducing a SON may enable tunable metamaterials [14] with potential applications in sub-diffraction imaging and waveguide devices.…”