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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.

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Magnification in metamaterial hyperlenses has been demonstrated using curved geometries or tapered devices, at frequencies ranging from the microwave to the ultraviolet spectrum. One of the main issues of such hyperlenses is the difficulty in manufacturing. In this letter, we numerically and experimentally study a wire medium prism as an imaging device at THz frequencies. We characterize the transmission of the image of two sub-wavelength apertures, observing that our device is capable of resolving the apertures and producing a two-fold magnified image at the output. The hyperlens shows strong frequency dependent artefacts, a priori limiting the use of the device for broad-band imaging. We identify the main source of image aberration as the reflections supported by the wire medium and also show that even the weaker reflections severely affect the imaging quality. In order to correct for the reflections, we devise a filtering technique equivalent to spatially variable time gating so that ultra-broad band imaging is achieved.

An octagonal photonic crystal fiber (PCF) with an elliptical shape in the center core is numerically investigated for residual dispersion compensation in the wavelength range 1460-1675 nm. The designed fiber exhibits flattened negative dispersion over the S + C + L + U wavelength bands and an average dispersion of -465.5 ps/(nm·km) with an absolute dispersion variation of 10.5 ps/(nm·km). In addition, the proposed PCF shows a high birefringence of 2.68×10(-2) at the operating wavelength 1550 nm, which meets the requirement of high birefringence. Moreover, the variation of two air holes in the first ring up to 5% ensures an average dispersion of -491.5 ps/(nm·km) with a dispersion variation of 13 ps/(nm·km), and birefringence reaches up to 3×10(-2). Furthermore, to evaluate the sensitivity of the fiber dispersion properties, ±5% variation in the optimum parameters is studied.

We report a novel hollow-core asymmetric conjoined-tube anti-resonant (HC-ACTAR) fiber for efficient and low-loss THz wave guidance. The cladding tubes of the proposed HC-ACTAR fiber is formed by conjoining a half circle and a half elliptical tube and is placed in the radial direction. We observe that the proposed fiber is superior in terms of achieving low-loss and low dispersion in a wide range of frequencies than the previously reported designs. We show that our proposed HC-ACTAR fiber ensures lowest loss of 0.034 dB/m at 1 THz and marinates a low-loss window of 0.5 THz. Moreover, the proposed fiber has promising optical properties in the THz regime such as low bending loss, broadband flattened dispersion, and effective single-mode guidance, which are essential for efficient THz wave guidance.