Surface wave manipulation by plasmonic metasurface based on mode resonance

Baoshan Guo

doi:10.1038/s41598-021-82948-0

Abstract

We proposed a method to manipulate the surface waves with a deep subwavelength metasurface by applying resonators with interfering mode resonance. The simulation results demonstrate that a single deep subwavelength obstructed groove can effectively control the propagation of surface terahertz (THz) waves by a small step increase (< 1/20 λ) of the depth or a slight change of refractive index (Δn = 0.1). The surface waves transmitted and reflected by the single groove can be controlled periodically by increasing the groove depth or refractive index with a high efficiency owing to the mode resonance between surface spoof plasmonics modes and groove cavity modes. The generated circle resonance mode provides a new idea for the development of THz devices. Importantly, the transmitted or reflected intensity of the surface wave is also enhanced by the Mode resonance. It is a simple and effective method to operate surface THz waves and manufacture more compact integrated optical devices in deep subwavelength scale.

Highlights

When Δd = 36 μm, the resonance between the surface spoof plasmonics mode and groove cavity mode forms a new circle resonance mode as shown in Fig. 4e, which is the physical reason of the deep subwavelength single grey groove can manipulate the surface wave
It has been demonstrated that the propagation characteristics of surface waves can be efficiently controlled by a single deep subwavelength groove with only 4 μm depth changing (< 1/20 λ) or refractive index changing of 0.1
We can use a few or more special grooves of different depth or refractive index located at different positions to manipulate the EM waves of different frequencies by the mode resonance between the plasmonic mode and groove cavity mode

Summary

Introduction

The depth and refractive index of the filling media of the single grey groove are the main parameters to control the propagation of surface waves. According to the FDTD simulation results (Fig. 2), the surface wave intensities before (reflection) and after (transmission) the single groove are all changed periodically with the increase of groove depth (Δd) or refractive index (Δn).

Results

Conclusion