Long Range Surface Plasmons in Multilayer Structures

TL;DR

This paper introduces a novel design strategy for asymmetric multilayer structures supporting long range surface plasmons, achieving extended propagation lengths and enhanced biosensing capabilities.

Contribution

It presents a Fresnel coefficient pole analysis method for designing LRSP-supporting structures with minimized losses and provides semi-analytic sensing parameters for biosensing applications.

Findings

Propagation lengths up to 2mm for LRSPs.

Reduced electric field intensity in metal layers.

Achieved surface sensing parameter G = 1.28(1/nm).

Abstract

We present a new strategy, based on a Fresnel coefficient pole analysis, for designing an asymmetric multilayer structure that supports long range surface plasmons (LRSP). We find that the electric field intensity in the metal layer of a multilayer LRSP structure can be even slightly smaller than in the metal layer of the corresponding symmetric LRSP structure, minimizing absorption losses and resulting in LRSP propagation lengths up to 2mm. With a view towards biosensing applications, we also present semi-analytic expressions for a standard surface sensing parameter in arbitrary planar resonant structures, and in particular show that for an asymmetric structure consisting of a gold film deposited on a multilayer of SiO2 and TiO2 a surface sensing parameter G = 1.28(1/nm) can be achieved.