Generation of a Conjoint Surface Plasmon by an Infrared Nano‐Antenna Array

Abstract

Localized surface plasmons (LSP) excited by optical fields have many potential applications resulting from their ability in detecting ultra‐small, ambient refractive index change. Current methods using surface nano‐patterning by means of lithography have given rise to LSP of limited propagation and interaction lengths, meaning that practical applications remain challenging. This article describes a new all‐optical method of generating LSP by means of a carefully fabricated low‐dimensional nano‐structured material using a direct‐write photochemical lithography. It is shown that the resulting array of localized SPs combine or “Conjoin” to have an unprecedented large interaction length, via coupled evanescent fields, giving rise to superior spectral sensitivities; several orders of magnitude better than those quoted elsewhere and reaching 6 × 103 nm RIU−1 in the aqueous regime and 104 nm RIU−1 in the gaseous regime. Numerical modeling is performed that shows this design of plasmonic platform is capable of producing sensitivities of 105–106 nm RIU−1. It is believed the results achieved in this investigation show that a unique conjoint SP operational mode will significantly impact areas of interest, such as single molecular dynamics, drug delivery systems, etc.

A Review: Application and Implementation of Optic Fibre Sensors for Gas Detection

“…There is a substantial amount of published work using spectroscopic absorption relating to molecular transitions in near-and mid-infrared spectra, which is used in conjunction with a The third plasmonic fibre sensor is based on the strong coupling of adjacent LSP on neighbouring nano-antennae, or conjoined LSPs. These conjoined LSPs effectively create a conjoined surface plasmon [44] that arches over the array of nano-antennae; a typical array is shown in Figure 4e. This creates an evanescent field that is suspended above the majority of the nanostructured surface of the sensor, this can be seen from FEM modelling and the resultant associated E/H fields of the conjoined infrared surface plasmon are shown in Figure 4f.…”

“…Group 3-evanescent field sensors, including in-fiber Mach-Zehnders, exposed fibre cores, conically tapered fibres, and random-hole optical fibers [33][34][35][36][37][38]. Group 4-plasmonic sensors, including surface plasmon resonance, localised surface plasmons, and conjoined surface plasmon [39][40][41][42][43][44].…”