Showing posts with label Alessio Stefani. Show all posts
Showing posts with label Alessio Stefani. Show all posts

Sunday, February 11, 2018

Abstract-Enhanced terahertz magnetic dipole response by subwavelength fiber


Shaghik Atakaramians,  Ilya V. Shadrivov, Andrey E. Miroshnichenko,   Alessio Stefani, Heike Ebendorff-Heidepriem, Tanya M. Monro, Shahraam Afshar,

http://aip.scitation.org/doi/10.1063/1.5010348

Dielectric sub-wavelength particles have opened up a new platform for realization of magnetic light. Recently, we have demonstrated that a dipole emitter by a sub-wavelength fiber leads to an enhanced magnetic response. Here, we experimentally demonstrate an enhanced magnetic dipole source in the terahertz frequency range. By placing the fiber next to the hole in a metal screen, we find that the radiation power can be enhanced more than one order of magnitude. The enhancement is due to the excitation of the Mie-type resonances in the fiber. We demonstrate that such a system is equivalent to a double-fiber system excited by a magnetic source. This coupled magnetic dipole and optical fiber system can be considered a unit cell of metasurfaces for manipulation of terahertz radiation and is a proof-of-concept of a possibility to achieve enhanced radiation of a dipole source in proximity of a sub-wavelength fiber. It can also be scaled down to optical frequencies opening up promising avenues for developing integrated nanophotonic devices such as nanoantennas or lasers on fibers.

Saturday, December 30, 2017

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.

Friday, June 23, 2017

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