Efficient end-fire coupling of surface plasmons in a metal waveguide

Abstract

We present a semi-analytical study exploring the end-fire coupling of an incident beam into a surface plasmon mode propagating on a metal-dielectric interface. An energy-conserving projection method is used to solve for the resultant reflected and transmitted fields for a given incident beam, thereby determining the efficiency of the surface plasmon coupling. The coupling efficiency is found to be periodic with waveguide width due to the presence of a transversely propagating surface plasmon. Optimisation of the incident beam parameters, such as beam width, position and wavelength leads to numerically observed maximum efficiencies of approximately 80% when the beam width roughly matches the width of the surface plasmon.

Efficient butt-coupling of surface plasmons on a silver-air interface

“…Only the fundamental results of the projection method are given here as detailed derivations are similar to those published earlier. 9 The projections of each Region II mode onto the set of Region I modes, and vice versa, are stored in the J and K matrices where the pq th element of each are…”

Large-Scale Inverse Design of a Planar On-Chip Mode Sorter

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“…field [18]. In the past few decades, experimental and theoretical investigations(for an intuitive explanation of dealing with plasmonic loss for waveguide application, see [19]) report stable propagation of linear and nonlinear SPWs employing ultra-low loss metallic-type layers such as single-crystal [20] and mono-crystal [21] metallic film, structured Fano metamaterials [22], semiconductor metamaterials [23] and superconducting metamaterials [24].…”