Manipulating the plasmon-induced transparency in terahertz metamaterials

Zhongyang Li,Jianqiang Gu,Yingfang Ma,Jiaguang Han,Weili Zhang,Ran Huang,Ranjan Singh,Zhen Tian

doi:10.1364/oe.19.008912

Abstract

Coupling between superradiant and subradiant mode resonators in a metamaterial unit cell plays an important role in observing the sharp transparency peak due to destructive interference between the resonators. This effect is enhanced as the resonators are brought closer to each other in a conventional planar arrangement. We present a novel coupling scheme of planar terahertz metamaterial to tune the plasmon-induced transparency peak by physically varying the distance between the superradiant and the subradiant resonators in such a way that the transparency peak begins to disappear as the coupled resonators are brought closer than a critical separation distance. The effect is attributed to the disappearance of the resonant behavior of the subradiant resonator in a closely coupled regime. The simple planar design presented here demonstrates a scheme to manipulate the electromagnetically induced transparency-like behavior in terahertz metamaterials and this could lead to the development of unique slow light devices for terahertz applications.

Highlights

Electromagnetic induced transparency (EIT) is an appealing physical phenomenon where the otherwise opaque medium becomes transparent for a probe laser if modified by a coupling laser beam [1]
These works have theoretically and experimentally demonstrated that the plasmon-induced transparency (PIT) effect can be realized in metamaterials via destructive interference between the superradiant and subradiant plasmonic modes or by breaking the symmetry of metamaterial system at microwave, terahertz, and optical frequencies [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]
We present a new type of PIT design in the terahertz regime with a systematic study of how the PIT spectral response can be controlled by changing the spatial configurations of “metamaterial molecules”

Summary

Introduction

Electromagnetic induced transparency (EIT) is an appealing physical phenomenon where the otherwise opaque medium becomes transparent for a probe laser if modified by a coupling laser beam [1]. We experimentally and numerically demonstrate that the relative distance between two nearby constituent elements in the metamaterial structure plays a critical role in modifying the PIT spectral response in such a way that the transparency peak begins to disappears when the resonators are brought closer than a certain critical distance This is in sharp contrast to the previously observed PIT effects in which the close distance between the superradiant and subradiant resonators led to enhanced transparency [5,6]

Measured results and numerical analysis

Conclusion