Fabricating Metamaterials Using the Fiber Drawing Method

Abstract

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1 . They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2 . This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3 , negative refractive index materials 4 , and lenses that resolve objects below the diffraction limit 5 . However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano-and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size [6][7] . Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8 . We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10 , using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 °C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro-and nano-scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Hybrid antiresonant metamaterial waveguides for THz and IR

“…In fact, loss as low as 2.3 dB/km are achievable at wavelengths around 1 mm. We fabricated the metamaterial structure by using the fiber drawing technique [4]. We used PMMA as dielectric and Indium as metal.…”

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.…”

Hybrid Optical Fibers – An Innovative Platform for In‐Fiber Photonic Devices

“…[ 88 ] From a practical perspective, using direct drawing techniques for fabricating metamaterials [ 89 ] allows the production of large sample volumes required for real-world applications. The experimental work demonstrating iMMs is based on using polymers as the dielectric (PMMA, polycarbonate, cycloolefi n polymer (COP) Zeonex) and indium as the metal, [ 90 ] which satisfi es the compatibility criteria for co-drawing described in Section 2.1 (melting point of indium is 157 °C, drawing temperature 200 °C). Fiber-based iMM were fabricated by a multiple version of the stack-and-draw process of singlewire fi bers, leading to arrays of cm 2 areas containing more than 10 4 wires.…”