Electrical Phase Control Based on Graphene Surface Plasmon Polaritons in Mid-infrared.

Yindi Wang,Shulong Wang,Haifeng Zhang,Hongxia Liu,Ming Cai,Yanbin Qiao

doi:10.3390/nano10030576

Yindi Wang, Shulong Wang + Show 4 more

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https://doi.org/10.3390/nano10030576

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Abstract

Phase modulation of light is the core of many optoelectronic applications, such as electro-optic switch, sensors and modulators. Graphene Surface plasmon polaritons (SPPs) exhibit unique properties in phase modulation including dynamic tunability, a small driving voltage and small device size. In this paper, the novel phase modulation capability of graphene SPPs in mid-infrared are confirmed through theory and simulation. The results show that graphene SPPs can realize continuous tuning of the phase shift at multiple wavelengths in mid-infrared, covering the phase range from 0° to 360°. Based on these results, a sandwich waveguide structure of dielectric–graphene–dielectric with a device length of 800 nm is proposed, which shows up to 381° phase modulation range at an operating wavelength of 6.55 µm, given a 1 V driving voltage. In addition, the structure size is much shorter than the wavelength in mid-infrared and can realize sub-wavelength operation. This work paves the way to develop graphene-based tunable devices for mid-infrared wave-front control.

Highlights

Surface plasmon polaritons (SPPs), the electromagnetic waves coupled to charge excitations on the surface of metal, are widely applied in sub-wavelength-scale optical processing [1]
Because of the breakthrough of the diffraction limit and the ultra-compact mode confinement, SPPs have become the cornerstones of various applications, including optical metamaterials, ultra-sensitive optical biosensors [2,3,4] and quantum information processing [5]
SPPs based on metals have been widely used, because most studies on SPPs focus on precious metals represented by silver and gold [4,6,7,8,9]

Summary

Introduction

Surface plasmon polaritons (SPPs), the electromagnetic waves coupled to charge excitations on the surface of metal, are widely applied in sub-wavelength-scale optical processing [1]. Previous research on graphene has proven that this material is a zero-gap semiconductor and its chemical potential can be tuned dynamically [15], which can be doped to high values of carrier concentrations either electrically or chemically. These unique properties make graphene a potential material for tunable optical devices such as modulators, polarizers, sensors, etc.

Results

Conclusion