Omnidirectional negative refraction with wide bandwidth introduced by magnetic coupling in a tri-rod structure

Abstract

A tri-rod structure, which can be seen as a combination of nanorod pairs reported by Shalaev [Opt. Lett. 30, 3356 (2005)], is proposed to realize negative refractions at infrared frequencies. In this system, a magnetic coupling effect is found between the two nanopairs and it results in two magnetic resonance modes: one mode at 146.6 THz and the other mode at 154.1 THz. The retrieved effective indices from scattering (S) parameters show that this coupling effect plays an important role in improving the negative property of the metamaterial. It can help to realize omnidirectional negative refractions and broaden the bandwidth of negative refraction. Metamaterials composed from tri-rod elements are used to simulate the negative-refraction behaviors of the electromagnetic wave with different propagation directions, providing direct evidence for the retrieved results. © 2007 The American Physical Society.