Sensitivity increasing in plasmonic optical sensor with (Au-SiO2) aperture arrays on a Bragg fiber endface

Abstract

Abstract In this paper, we theoretically demonstrate a sensitivity increasing in the plasmonic optical sensor (POS) with (Au-SiO2) aperture arrays on a core-cladding (C-C) cylindrical Bragg fiber endface based on the extraordinary optical transmission (EOT) property. Numerical investigations show that the design of C-C Bragg fiber significantly affects the sensitivity enhancement due to Fresnel reflection compared with C-C fiber by using a mode analysis approach. The essential parameters including the thickness of Au and SiO2, the refractive index (RI) as well as its width of a torus in the fiber cladding and the gap between two adjacent tori, which affect the EOT, are discussed and optimized. A high average sensitivity of 284 ± 5 nm/RIU of the POS in the sensing range 1.30–1.42 with high linearity is achieved for the peak wavelength interrogation. It is demonstrated that a significant sensitivity increases in the proposed POS (the thickness is 100 nm, the RI is 1.5, the width is 20 nm and the gap is 50 nm) up to 219 arbitrary units (∼337%), which is clearly observed more than that of C-C fiber. The averaged figure of merit (FOM) of the proposed POS is calculated to be 5.2 RIU−1. Our findings hold potential applications in designing and optimizing a high-performance POS.