Enhanced spatial near-infrared modulation of graphene-loaded perfect absorbers using plasmonic nanoslits.

Yijun Cai,Longfang Ye,Qing Huo Liu,Jinfeng Zhu,Jianyang Zhou,Timothy Lin,Zhiping Cai

doi:10.1364/oe.23.032318

Yijun Cai, Longfang Ye + Show 5 more

Open Access

https://doi.org/10.1364/oe.23.032318

Copy DOI

Abstract

Modulating spatial near-infrared light for ultra-compact electro-optic devices is a critical issue in optical communication and imaging applications. To date, spatial near-infrared modulators based on graphene have been reported, but they showed limited modulation effects due to the relatively weak light-graphene interaction. In combination with graphene and metallic nanoslits, we design a kind of ultrathin near-infrared perfect absorber with enhanced spatial modulation effects and independence on a wide range of incident angles. The modulated spectral shift of central wavelength is up to 258.2 nm in the near-infrared range, which is more promising in applications than state-of-the-art devices. The modulation enhancement is attributed to the plasmonic nanoslit mode, in which the optical electric field is highly concentrated in the deep subwavelength scale and the light-graphene interaction is significantly strengthened. The physical insight is deeply revealed by a combination of equivalent circuit and electromagnetic field analysis. The design principles are not only crucial for spatial near-infrared modulators, but also provide a key guide for developing active near-infrared patch nanoantennas based on graphene.

Highlights

Plasmonic perfect absorbers (PPAs) have attracted a surge of research interest due to their extensive applications from ultraviolet to terahertz frequencies, including sensors [1], thermal imaging [2], light trapping [3], and photovoltaics [4,5]
In order to significantly enhance the capacity of electrical tuning for plasmonic perfect absorbers (PPAs) in the near-infrared range, we propose loading graphene in the dielectric layer of an MDM plasmonic absorber in combination with a guided gap-plasmon mode and a plasmonic nanoslit mode
The modulation efficiency predicted in the simulated nanostructure is much higher than some state-of-the-art devices based on hybrid graphene-plasmonic nanostructures [29, 30], and this indicates that the proposed nanostructure is more competitive for developing applications of active spatial near-infrared modulators

Summary

Introduction

Plasmonic perfect absorbers (PPAs) have attracted a surge of research interest due to their extensive applications from ultraviolet to terahertz frequencies, including sensors [1], thermal imaging [2], light trapping [3], and photovoltaics [4,5]. Strong electrical tunability of electromagnetic response in PPAs using graphene has so far not been reported at the range of near-infrared light, which is dramatically significant for many technological applications, including detection, biosensing, and telecommunication [15,16,17,18]. This is because in the near-infrared range intrinsic graphene generally acts as a lossy dielectric material with frequency-independent absorption and exhibits relatively weak lightmatter interaction without the support of surface plasmon polaritons (SPPs) [19]

Methods

Results

Conclusion