Abstract-Experimental demonstration of a magnifying prism hyperlens at THz frequencies

 Md. Samiul Habib,  Alessio Stefani,  Atakaramians, Simon C. Fleming, Alexander Argyros, Boris T. Kuhlmey

http://ieeexplore.ieee.org/document/8107865/references

We experimentally demonstrate a magnifying wire medium (WM) prism hyperlens at THz frequencies. The different lengths of wire in the prism have different resonance frequencies, so that there is no frequency at which a good image is possible. We show that using spatially varying time gating or frequency convolution the resonant response can be removed and experimentally demonstrate sub-diffraction magnified imaging of a sub-wavelength double aperture.

Abstract-Tunable metamaterials fabricated by fiber drawing

Simon Fleming, Alessio Stefani, Xiaoli Tang, Alexander Argyros, Daniel Kemsley, James Cordi, and Richard Lwin

https://www.osapublishing.org/josab/abstract.cfm?uri=josab-34-7-D81

We demonstrate a practical scalable approach to the fabrication of tunable metamaterials. Designed for terahertz (THz) wavelengths, the metamaterial is comprised of polyurethane filled with an array of indium wires using the well-established fiber drawing technique. Modification of the dimensions of the metamaterial provides tunability; by compressing the metamaterial we demonstrated a 50% plasma frequency shift using THz time-domain spectroscopy. Releasing the compression allowed the metamaterial to return to its original dimensions and plasma frequency, demonstrating dynamic reversible tunability.

© 2017 Optical Society of America

Abstract-Elliptical metallic hollow fiber inner-coated with non-uniform dielectric layer

Xiaoli Tang, Zhuzheng Yu, Xuecou Tu, Jian Chen, Alexander Argyros, Boris T. Kuhlmey, and Yiwei Shi
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-17-22587

We report on the fabrication and characterization of an elliptical hollow fiber inner coated with a silver layer and a dielectric layer for polarization maintaining and low loss transmission of terahertz (THz) radiation. The primary purpose of adding the dielectric layer is to prevent the silver layer from oxidation. The thickness of the dielectric layer is non-uniform owing to the surface tension of the coating, which was initially applied as a liquid. Transmission loss and polarization maintenance are experimentally characterized. Effects of the dielectric layer on transmission properties are analyzed by comparing the fiber to Ag-only fiber. Results show that a dielectric layer with thickness less than λ/10 can effectively decreases the power distributed on the metal surface and thus can practically reduce loss resulting from roughness of the silver layer. Bending effects on transmission loss and polarization maintenance are also investigated.

© 2015 Optical Society of America

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Abstract-Metamaterial fibres for subdiffraction imaging and focusing at terahertz frequencies over optically long distances

• Alessandro Tuniz,
• Korbinian J. Kaltenecker,
• Bernd M. Fischer,
• Markus Walther,
• Simon C. Fleming,
• Alexander Argyros
• & Boris T. Kuhlmey

• http://www.nature.com/ncomms/2013/131028/ncomms3706/full/ncomms3706.html

Using conventional materials, the resolution of focusing and imaging devices is limited by diffraction to about half the wavelength of light, as high spatial frequencies do not propagate in isotropic materials. Wire array metamaterials, because of their extreme anisotropy, can beat this limit; however, focusing with these has only been demonstrated up to microwave frequencies and using propagation over a few wavelengths only. Here we show that the principle can be scaled to frequencies orders of magnitudes higher and to considerably longer propagation lengths. We demonstrate imaging through straight and tapered wire arrays operating in the terahertz spectrum, with unprecedented propagation of near field information over hundreds of wavelengths and focusing down to 1/28 of the wavelength with a net increase in power density. Applications could include in vivo terahertz-endoscopes with resolution compatible with imaging individual cells.