Metal-dielectric layered structure supporting surface plasmons: Numerical modelling by the method of single expression

Surface plasmons' (SPs) excitation in Kretschmann-type structure, where a thin metallic layer upon the dielectric prism substituted by a metal-dielectric layered (MDL) structure, is analysed via numerical simulation. Four possible alternations in MDL structure at fixed metallic and dielectric layers' thickness are considered and favorable structure is indicated. It is revealed, that MDL structures support SPs when the sum of metallic layers' thickness is about the thickness of a single metallic layer in conventional Kretschmann structure.

1. Introduction

Surface plasmons are specific electromagnetic (EM) waves propagating along the metal-dielectric interface evanescently diminishing in the perpendicular direction to this interface [1]–[4]. Wavelength-scale field confinement in the vicinity of metal-dielectric interface possess unique features of SPs in sensing [5]–[8] and waveguiding [9]–[13]. Optical field confinement at the metal-dielectric interface is accompanied by strong enhancement of electric and magnetic field components having their maximum values at the interface. Surely this phenomenon is advantageous for SPs application in sensing, mainly in Kretschmann configuration [5]–[8]. Location of analyte in region of high field intensity ensures efficient detection of analytes' permittivity change, what is one of the goals in optical sensing.