Dual-Spectral Plasmon-Induced Transparent Terahertz Metamaterial with Independently Tunable Amplitude and Frequency

Tong Wu,Chen Chen,Yang Gao,Jing Han,Yachen Gao,Yabin Shao,Yang Jia,Guan Wang

doi:10.3390/nano11112876

Tong Wu, Chen Chen + Show 6 more

Open Access

https://doi.org/10.3390/nano11112876

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Abstract

A bifunctional tunable metamaterial composed of pattern metal structure, graphene, and strontium titanate (STO) film is proposed and studied numerically and theoretically. The dual plasmon-induced transparency (PIT) window is obtained by coupling the bright state cut wire (CW) and two pairs of dark state dual symmetric semiring resonators (DSSRs) with different parameters. Correspondingly, slow light effect can also be realized. When shifting independently, the Fermi level of the graphene strips, the amplitudes of the two PIT transparency windows and slow light effect can be tuned, respectively. In addition, when independently tuning the temperature of the metamaterial, the frequency of the dual PIT windows and slow light effect can be tuned. The physical mechanism of the dual-PIT was analyzed theoretically by using a three-harmonic oscillator model. The results show that the regulation function of the PIT peak results from the change of the oscillation damping at the dark state DSSRs by tuning conductivity of graphene. Our design presents a new structure to realize the bifunctional optical switch and slow light.

Highlights

In order to investigate the mechanism of double plasmon-induced transparency (PIT) transparency windows, we conducted the simulation for four arrays, composed of cut wire (CW) arrays, upper double symmetric semiring resonators (UDSSRs), bottom double symmetric semiring resonators (BDSSRs) and a combined array of them
When the CW, UDSSRs and BDSSRs are combined into a unit cell, under x-polarized electric field excitation, two PIT windows arise because of the destructive interference caused by the coupling of the two resonance of 12 modes and localized surface plasmon resonance (LSPR) mode
The frequency function double PIT windows andsimulation group delay can be realized by olayer graphene strips and strontium titanate (STO) selection film into

Summary

Introduction

Induced transparency (EIT) is an effect resulting from quantum destructive interference. It can generate a narrow-band transparent window when light propagates through an originally opaque medium [1,2]. Compared with the traditional EIT effect, plasmon-induced transparency (PIT) effect overcomes these harsh conditions [3]. Many researchers have focused on various metamaterial structures to achieve PIT, which is the analog of EIT effect [4,5,6,7,8]. At a PIT peak region, strong dispersion can occur, causing slow light effect which can be used in optical information processing [13,14,15,16]

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