Near-field surface plasmons on quasicrystal metasurfaces.

Quanlong Yang,Weili Zhang,Yanfeng Li,Sergey S Kruk,Jianqiang Gu,Xueqian Zhang,Yongmin Liu,Shaoxian Li,Ranjan Singh,Jiaguang Han,Quan Xu

doi:10.1038/s41598-016-0027-y

Abstract

Excitation and manipulation of surface plasmons (SPs) are essential in developing cutting-edge plasmonic devices for medical diagnostics, biochemical spectroscopy and communications. The most common approach involves designing an array of periodic slits or grating apertures that enables coupling of the incident light to the SP modes. In recent years, plasmonic resonances, including extraordinary optical transmission through periodic arrays, quasicrystals and random aperture arrays, have been investigated in the free space. However, most of the studies have been limited to the far field detection of the transmission resonance. Here, we perform near-field measurements of the SPs on quasicrystal metasurfaces. We discover that the reciprocal vector determines the propagation modes of the SPs in the quasicrystal lattice which can be well explained by the quasi-momentum conservation rule. Our findings demonstrate vast potential in developing plasmonic metasurfaces with unique device functionalities that are controlled by the propagation modes of the SPs in quasicrystals.

Highlights

Surface plasmons (SPs) in periodic subwavelength aperture arrays have been widely investigated because of their potential applications in near-field imaging[1,2,3,4,5], sensing[6] and extraordinary optical transmission (EOT)[7,8,9]
For a quasicrystal metasurfaces (QCMs) with rotational symmetry, the reciprocal vectors (Gi) in the Fourier space have a direct relationship with the wave vector of the allowed SPs10
The wave vector ksp depends on the distributions of the slit arrays, and SPs excited from the QCMs could propagate in the directions that correspond to all the involved reciprocal vectors Gi

Summary

Introduction

Surface plasmons (SPs) in periodic subwavelength aperture arrays have been widely investigated because of their potential applications in near-field imaging[1,2,3,4,5], sensing[6] and extraordinary optical transmission (EOT)[7,8,9]. Our findings clearly reveal the role and impact of the structural periodicity on SP propagation properties supported by metasurfaces, opening a new avenue to manipulate SPs. For a QCM with rotational symmetry, the reciprocal vectors (Gi) in the Fourier space have a direct relationship with the wave vector of the allowed SPs10. The wave vector ksp depends on the distributions of the slit arrays, and SPs excited from the QCMs could propagate in the directions that correspond to all the involved reciprocal vectors Gi. To confirm the preceding prediction based on the quasi-momentum conservation rule, we calculated and examined the propagation of the SPs on metallic QCM that possess 8-fold and 10-fold rotational symmetry. It is found that the propagation modes of the SPs on 8-fold QCM exhibit an identical rule of reciprocal vectors This prediction can be applied to QCMs with different order rotational symmetry. The unique properties of QCMs offer a new degree of freedom for excitation, control and propagation of SPs

Methods

Results

Conclusion