Significantly enhanced sensitivity using a gold aperture arrays-dielectric hybrid structure in optical fiber sensor

Abstract

In this paper, we propose a novel gold aperture arrays-dielectric hybrid structure in optical fiber sensor (OFS) based on the extraordinary optical transmission (EOT) property to explore the possibility of increasing its sensitivity. Numerical investigations show that the match between effective indices of the fundamental core mode and surface plasmon polariton (SPP) mode of gold aperture arrays-dielectric interface affects the sensitivity enhancement by using mode analysis approach. The essential parameters of the hybrid structure including the gold film thickness and dielectric refractive index (RI) as well as its thickness, which affect the EOT, are discussed and optimized. An average sensitivity of 180 ± 7 nm/RIU in the sensing range 1.30–1.45 with high linearity is obtained. It is demonstrated that a significant sensitivity enhancement with a dielectric layer (its RI is 1.90 and its thickness is 50 nm) up to 105 arbitrary units (∼140%) is clearly observed more than that without a dielectric layer. The averaged figure of merit (FOM) of the proposed OFS is calculated to be 12.5 RIU−1. Our findings indicate that this proposed hybrid structure may offer great potential in designing and optimizing a high-performance OFS.