Additional modes in a waveguide system of zero-index-metamaterials with defects

Abstract

Zero-index-metamaterials (ZIM) have drawn much attention due to their intriguing properties and novel applications. Particularly, in a parallel plated ZIM waveguide system with defects, total reflection or transmission of wave can be achieved by adjusting the properties of defects. This effect has been explored extensively in different types of ZIM (e.g., epsilon-near-zero metamaterials, matched impedance ZIM, or anisotropic ZIM). Almost all previous literatures showed that only monopole modes are excited inside the defects if they are in circular cylinder shapes. However, the underlying physics for excited modes inside defects is wrongly ignored. In this work, we uncover that additional modes could be excited by theoretical analysis, which is important as it will correct the current common perception. For the case of matched impedance zero-index metamaterials (MIZIM), the additional dipole modes can be excited inside the defects when total transmission occurs. Moreover, we also observe the same results in Dirac-cone-like photonic crystals which have been demonstrated theoretically and experimentally to function as MIZIM. For another case of epsilon-near-zero metamaterials (ENZ), we find that additional higher order modes (e.g., tri-pole) can be excited inside the defects when total transmission happens. Numerical simulations are performed to verify our finding regarding the additional modes.

Applications of gradient index metamaterials in waveguides

“…It is noted that, by introducing ZIMs with defects 13 14 15 into a waveguide, tunable transmission effect also could be realized. Such tunable transmission effect depends on the resonances 16 of cavity modes, which is very sensitive to the material parameters of defects. Moreover, if tiny material loss of ZIMs is taken into consideration, transmission will be lowered.…”

“…After that, metamaterials have drawn extensive attention and more applications are proposed such as electromagnetic concentrators 7 8 , field rotators 9 10 and so forth. More recently, as a special kind of metamaterials, zero index metamaterials (ZIMs) are also used to manipulate the propagation of light, e.g., realizing bending waveguide 11 12 , controlling total transmission or reflection 13 14 15 16 in a waveguide, achieving asymmetric transmission 17 and inducing inhomogeneous field via cavity modes 18 . Moreover, controlling the propagation of light is also realized by metasurfaces 19 20 21 , which could be regarded to change the conventional laws of reflection and refraction.…”

Simple examples of perfectly invisible and trapped modes in waveguides

“…However, one can speak of backscattering invisibility. The latter problem has been investigated numerically (|R| small) for example in [34,16] for water wave problems and in [1,13,31,32,18], with strategies based on the use of new "zero-index" and "epsilon near zero" metamaterials, in electromagnetism (see [17] for an application to acoustics).…”

Team organization may help swarms of flies to become invisible in closed waveguides

“…In this setting, examples of invisible obstacles, obtained via numerical simulations, can be found in literature. We refer the reader to [22] for a water waves problem and to [1,21,47,48,25] for strategies using new "zero-index" and "epsilon near zero" metamaterials in electromagnetism (see also [23] for an application to acoustics). The technique that we propose in this article differs from the ones presented in the above mentioned works because it is exact in the sense that it is a rigorous proof of existence of invisible obstacles.…”