The role of leaky plasmon waves in the directive beaming of light through a subwavelength aperture

D R Jackson,R Qiang,A A Oliner,F Capolino,J Chen

doi:10.1364/oe.16.021271

D R Jackson, R Qiang + Show 3 more

Open Access

https://doi.org/10.1364/oe.16.021271

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Abstract

We show that the enhanced directivity phenomenon for light passing through a subwavelength aperture in a silver film with corrugations on the exit face, is due to a leaky wave that decays exponentially from the aperture. We show quantitatively that the field along the interface of the silver film is dominated by the leaky wave, and that the radiation of the leaky wave, supported by the periodic structure, yields the directive beam. The leaky wave propagation and attenuation constants parameterize the physical radiation mechanism, and provide important design information for optimizing the structure. Maximum directivity occurs when the phase and attenuation constants are approximately equal.

Highlights

We show that the enhanced directivity phenomenon for light passing through a subwavelength aperture in a silver film with corrugations on the exit face, is due to a leaky wave that decays exponentially from the aperture
We show quantitatively that the field along the interface of the silver film is dominated by the leaky wave, and that the radiation of the leaky wave, supported by the periodic structure, yields the directive beam
We investigate here the fundamental physical phenomenon responsible for the directive beaming of light through a single subwavelength slit in a silver film, when the slit is surrounded by an optimized periodic structure [1,2,3,4]

Summary

Introduction

We investigate here the fundamental physical phenomenon responsible for the directive beaming of light through a single subwavelength slit in a silver film, when the slit is surrounded by an optimized periodic structure [1,2,3,4]. The term “leaky wave” has been used before as a general description of radiation effects on corrugated silver film structures at optical frequencies [2], it is clear that in this previous work there was no direct connection between an exponentially-decaying guided mode with a complex wavenumber and the directive beaming effect. This is established here for the first time, and the usefulness of the leaky-wave point of view is clearly demonstrated in optimizing the structure and predicting the radiation efficiency of the structure

Background and Discussion of Leaky Waves

Analysis

Results

Field at the Interface

Far-Field Radiation Pattern

Summary and Conclusions