Performance enhancement of a copper-based optical fiber SPR sensor by the addition of an oxide layer

Abstract

This article is dedicated to the numerical study of a fiber optic sensor based on surface plasmon resonance (SPR). This fiber is covered with a copper film protected by a layer of Indium Tin Oxide (ITO), to make the sensor suitable for chemical and biological applications with high sensitivity and high resolution. In this work, we studied the capabilities of different metals used in fiber optic sensors. We considered four metals; silver (Ag), copper (Cu), aluminium (Al), and gold (Au). As a result of a numerical simulation, the transmission characteristics of the SPR sensor are presented. We have found that Cu is the best candidate despite its poor stability in aqueous media. To overcome this problem, a protective layer of indium tin oxide ITO has been deposited on the copper layer. We also performed another comparison between three configurations (Cu + ITO, Ag + ITO, Au + ITO) of the sensor to confirm the choice of copper and to highlight the use of this metal. This comparison was done through the evaluation of the sensitivity and the signal-to-noise (SNR). It has been found that the best performances were obtained with a sensor based on Cu + ITO.