Design and performance analysis of PCF based plasmonic biosensor with optimized asymmetric slotted airhole

Abstract

Nowadays, sensors are being miniaturized due to the high demand for lightweight, small size, portable, compact structure, highly efficient, real-time, and cost-effective devices for sensing applications. Photonic crystal fiber (PCF) fulfills the demand mentioned above, providing an excellent guiding property and design freedom. Surface plasmon resonance (SPR) refers to the coupling of the surface plasmon wave and electromagnetic wave in between the metal-dielectric interface. It offers a highly sensitive, efficient, label-free, and real-time sensing technique. So, the combination of the PCF with SPR technology fulfills the all requirements of biosensors. To introduce the widely known SPR phenomenon, deposition of metals is compulsory. The sensing performance of a biosensor is highly dependent on the suitable selection of plasmonic material.

In this dissertation, a novel PCF-SPR biosensor is numerically characterized with high sensing performance for bio-analyte sensing particularly in the analyte refractive index (RI) ranging from 1.29 to 1.42. The proposed PCF-SPR sensor consists of a solid silica core and adjacent rectangular air holes in the cladding region. The entire outer surface of the proposed sensor is covered by a thin gold film to introduce the widely known SPR phenomenon. Sensing methodology is appropriately addressed and each of the designed parameters of the sensor structure is tuned sufficiently to find out the desired sensing performance. Finite element method (FEM) based mode solver software (COMSOL Multiphysics version 5.3a) is used with the help of Matlab interface to investigate the performance of the proposed sensor. Considering RI changes at the outer surface, appealing sensing performance such as maximum wavelength sensitivity of 2,16,000 nm/RIU and maximum amplitude sensitivity of 1138.52 RIU-1 is attained. In addition, the proposed sensor possesses a resolution of 4.63×10-7 RIU, linearity of 0.9861, a figure of merit of 1981.651 RIU-1, and detection accuracy of 0.019802 nm-1. However, the promising sensing characteristics of the proposed sensor indicate its potential to be effectively used for the perfect detection of the biochemical and organic samples in biochemical industries.