Tunable Low Threshold Optical Tristability at Terahertz Frequencies via a Pair of Parallel Graphene Layers’ Configuration

Yunyang Ye,Jiao Tang,Hui Zhou,Shengyou Qian,Zhiwei Zheng,Minzhu Xie,Leyong Jiang

doi:10.1155/2018/5679759

Abstract

We investigate theoretically the optical tristability of transmission at a pair of parallel graphene layers system. We discuss the influence of the graphene sheets on the hysteretic response of the TE-polarized transmitted light. It is demonstrated that the optical tristability in this configuration can be realized due to the giant third-order nonlinear conductivity of graphene and appropriate structure parameters. The tristable behavior of the transmitted light can be controlled via suitably varying the Fermi energy of the graphene. Besides, the optical tristable behavior is strongly dependent on the relaxation time of the graphene and the dispersion characteristics of the surrounding dielectrics. Moreover, the threshold of the optical tristability can be reduced by appropriately increasing the number of graphene layers, making this simple structure a good candidate for dynamic tunable and low threshold optical tristable device in the terahertz (THz) frequencies.

Highlights

Optical bistability and multistability devices are widely used in the areas of optoelectronics such as optical memory, optical transistor, all-optical logic gate, and all-optical switching due to their ability of harnessing optical nonlinear characteristics [1,2,3,4]
The phenomenon of optical multistability of four-level cascade-type cold atoms [9], semiconductor quantum well nanostructure [10], and polaritonic materials doped with nanoparticles [11] have raised heated research
We consider a structure composed of dielectric slab and graphene; both sides of dielectric slab are covered by monolayer graphene, as shown in Figure 1, where z direction is perpendicular to the plane of the monolayer graphene and a plane wave of amplitude Ei is normally incident on the structure, giving rise to a reflected and a transmitted wave with amplitudes Er and Et

Summary

Introduction

Optical bistability and multistability devices are widely used in the areas of optoelectronics such as optical memory, optical transistor, all-optical logic gate, and all-optical switching due to their ability of harnessing optical nonlinear characteristics [1,2,3,4]. People proposed various ways and methods to realize the generation and control of optical bistability such as Fabry-Perot cavities [5], nonlinear prism coupler [6], subwavelength metallic gratings [7], and semiconductor quantum well systems [8]. The partial characteristic of graphene can give full play to its advantage in the field of optical multistability. Gu et al have realized ultralow power resonant optical bistability in graphene-silicon hybrid optoelectronic devices for the first time [20]. Yin et al proposed a single dielectric layer sandwiched between two nonlinear graphene layers to realize the controllable transition between optical bistability and multistability [23]. Graphene-based optical devices with intrinsic optical tristability allow us to explore the promise of using such elements as the building block of future integrated optics and digital all-optical circuitry

Theoretical Model and Method

Results and Discussions

Conclusions