Realization of a Single-Layer Terahertz Magnetic Mirror

Qigejian Wang,Shahraam Afshar V,Shaghik Atakaramians,Heike Ebendorff-Heidepriem

doi:10.1109/access.2020.3045446

Qigejian Wang, Shahraam Afshar V + Show 2 more

Open Access

https://doi.org/10.1109/access.2020.3045446

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Abstract

We experimentally demonstrate a single-layer terahertz dielectric metasurface. The metasurface consists of an array of sub-wavelength fibers. It is shown that this single-layer terahertz metasurface has high transmission window and can also behave like a terahertz magnetic or electric mirror due to the excitation of resonances in the fibers. It is also observed that changing the excitation angle ( $\phi >5^{\circ })$ leads to appearance of new resonances, which narrows and widens the transmission window for s- and p- polarizations, respectively. By exploring the variation of resonances due to excitation of single, double or array of fibers, we have demonstrated that the individual element resonances can interact and lead to high transmission when the fibers are arranged in an array. The proposed single-layer metasurface that can operate both in transmission and reflection mode, opens new opportunities to develop single-layer terahertz devices for wavefront engineering.

Highlights

M ETASURFACES are planar metamaterials, usually composed of periodic, quasi-periodic or random units of sub-wavelength structures [1], [2]
The concept of the structure is based on our previous work, where we demonstrated that Mie or Whispering Gallery Mode (WGM) resonances can be excited in a sub-wavelength fiber with a relatively medium refractive index using point source excitation, leading to an enhanced magnetic response in THz frequency range [26]–[28], [48]
We notice that there are oscillations in the experimental results, which are due to etalon effect from the lenses (4-mm thick TPX lenses) and diffraction caused by the iris [54]

Summary

INTRODUCTION

M ETASURFACES are planar metamaterials, usually composed of periodic, quasi-periodic or random units of sub-wavelength structures [1], [2]. For the first time to the best of our knowledge, extraordinary electromagnetic properties of this single-layer structure at THz range; i.e. dielectric electric- or magnetic-mirror characteristics, near-unity transmission or reflection, and wide transmission window due to overlap of resonances. The concept of the structure is based on our previous work, where we demonstrated that Mie or WGM resonances can be excited in a sub-wavelength fiber with a relatively medium refractive index using point source excitation, leading to an enhanced magnetic response in THz frequency range [26]–[28], [48]. For single/ double/ triple fiber(s) simulations we have defined two ports as transmitter and receiver with the same size as the diameter of the iris we use for measurements

RESULTS AND DISCUSSION

INDIVIDUAL AND COLLECTIVE RESONANCES

CONCLUSIONS AND OUTLOOK