Directional excitation of surface plasmon using multi-mode interference in an aperture

M Z Alam,M Sheik-Bahae,Z Yang,M Mojahedi,J S Aitchison

doi:10.1038/s41598-020-78594-7

M Z Alam, M Sheik-Bahae + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-78594-7

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Abstract

Plasmonics is a promising technology that can find many applications in nanophotonics and biosensing. Local excitation of surface plasmons with high directionality is required for many of these applications. We demonstrate that by controlling the interference of light in a metal slot with the adjustment of the angle of incidence, it is possible to achieve highly directional surface plasmon excitation. Our numerical analysis of the structure showing a strong directionality of excited surface plasmon is confirmed by near field scanning measurements. The proposed structure can be useful for many applications including excitation of plasmonic waveguides, nanolithography, and optical sensing. To illustrate its usefulness, we experimentally demonstrate that it can be used for highly directional excitation of a dielectric loaded plasmonic waveguide. We also propose a simple structure for surface plasmon interference lithography capable of providing high image contrast using this scheme.

Highlights

Plasmonics is a promising technology that can find many applications in nanophotonics and biosensing
We have proposed and experimentally demonstrated that oblique backside illumination can be a simple method for achieving unidirectional Surface plasmon (SP) excitation
We show that light can be coupled to a dielectric loaded plasmon waveguide with high directionality by using this simple geometry

Summary

Introduction

Plasmonics is a promising technology that can find many applications in nanophotonics and biosensing. We demonstrate that by controlling the interference of light in a metal slot with the adjustment of the angle of incidence, it is possible to achieve highly directional surface plasmon excitation. As can be seen from the figures, the interactions of the modes can result in highly directional power flow in the half space above the metal surface. An illustration of this principle for unidirectional SP excitation can be found in18. The simplicity of our proposal can be useful for many nanophotonic applications

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