Optically Active Plasmonic Metasurfaces based on the Hybridization of In-Plane Coupling and Out-of-Plane Coupling

Dong Wu,Liu Yang,Zenghui Xu,Zhongyuan Yu,Li Yu,Yumin Liu,Han Ye,Rui Ma,Lei Chen,Chang Liu

doi:10.1186/s11671-018-2564-8

Dong Wu, Liu Yang + Show 8 more

Open Access

https://doi.org/10.1186/s11671-018-2564-8

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Abstract

Plasmonic metasurfaces have attracted much attention in recent years owing to many promising prospects of applications such as polarization switching, local electric field enhancement (FE), near-perfect absorption, sensing, slow-light devices, and nanoantennas. However, many problems in these applications, like only gigahertz switching speeds of electro-optical switches, low-quality factor (Q) of plasmonic resonances, and relatively low figure of merit (FOM) of sensing, severely limit the further development of plasmonic metasurface. Besides, working as nanoantennas, it is also challenging to realize both local electric FE exceeding 100 and near-perfect absorption above 99%. Here, using finite element method and finite difference time domain methods respectively, we firstly report a novel optically tunable plasmonic metasurface based on the hybridization of in-plane near-field coupling and out-of-plane near-field coupling, which provides a good solution to these serious and urgent problems. A physical phenomenon of electromagnetically induced transparency is obtained by the destructive interference between two plasmon modes. At the same time, ultrasharp perfect absorption peaks with ultra-high Q-factor (221.43) is achieved around 1550 nm, which can lead to an ultra-high FOM (214.29) in sensing application. Particularly, by using indium-doped CdO, this metasurface is also firstly demonstrated to be a femtosecond optical reflective polarizer in near-infrared region, possessing an ultra-high polarization extinction ratio. Meanwhile, operating as nanoantennas, this metasurface achieves simultaneously strong local electric FE(|Eloc|/|E0| > 100) and a near-perfect absorption above 99.9% for the first time, which will benefit a wide range of applications including photocatalytic water splitting and surface-enhanced infrared absorption.

Highlights

Plasmonic metasurfaces, as two-dimensional versions of metamaterials, have a wide range of promising phenomena and applications including polarization switching [1], beam rotator [2], Fano resonance [3–7], nanoantennas [8–10], negative refractive index [11, 12], near-perfect absorbers [13–15], and invisibility cloaking
Except for the polarization switching reported by Yang et al [1], most traditional polarizationselective devices, such as waveplates and polarizers based on electro-optical effects, are either static or operating with only gigahertz switching speeds, which are limited by the required electronics [45, 46]
For the phenomena or applications of end of the article induced transparency (EIT) effect, Fano resonance, and plasmonic nanoantennas based on a plasmonic metasurface, most of previously reported works usually suffer from these serious and urgent problems: (i) the broadening of plasmonic resonances owing to large optical losses in metals [5]; (ii) unadjustable operating wavelength of EIT effect or Fano resonances [35]; (iii) the challenge of achieving strong local electric field enhancements (|Eloc|/ |E0| > 100) and near-perfect absorption (> 99%) simultaneously [8]; (iv) generally, only gigahertz switching speeds of polarization-selective devices operating in visible or near infrared (NIR) region [1]

Summary

Introduction

As two-dimensional versions of metamaterials, have a wide range of promising phenomena and applications including polarization switching [1], beam rotator [2], Fano resonance [3–7], nanoantennas [8–10], negative refractive index [11, 12], near-perfect absorbers [13–15], and invisibility cloaking. Dayal et al demonstrated a whispering-gallerymode-based metallic metasurfaces realizing high Q (reaching 79) plasmonic Fano resonances at NIR frequencies [5] This reported Fano resonance can only be achieved at a specific wavelength, which is another common problem seriously restricting the further developments and applications of the Fano resonance or EIT phenomena. For the phenomena or applications of EIT effect, Fano resonance, and plasmonic nanoantennas based on a plasmonic metasurface, most of previously reported works usually suffer from these serious and urgent problems: (i) the broadening of plasmonic resonances owing to large optical losses in metals [5]; (ii) unadjustable operating wavelength of EIT effect or Fano resonances [35]; (iii) the challenge of achieving strong local electric field enhancements (|Eloc|/ |E0| > 100) and near-perfect absorption (> 99%) simultaneously [8]; (iv) generally, only gigahertz switching speeds of polarization-selective devices operating in visible or NIR region [1]

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