Biosensor Based on Photonic Crystal Fibre with Mode Coupling of a Dual-Core

Abstract

In recent years, photonic biosensors have attracted increasing attention due to the enormous range of applications in many fields to which they may be put, including medical diagnostics, environment monitoring, organic chemical detection, temperature sensing, and work with magnetic fields. In this work, photonic crystal fibre (PCF) was utilised as a biosensor using a Finite Element Method (FEM). Several important optical sensor properties such as the field distribution profiles, the real part of the effective refractive index and the relative sensitivity of the proposed PCF structure are affected by mode coupling between the fundamental mode and the second order super mode of the inner and outer cores, respectively. These properties were thus those studied by applying FEM. The proposed biosensor can thus be used for bio-sensing, as the holes in the PCF are filled with analytes. Relatively high sensitivity can thus be obtained using appropriate design by selecting design parameters such as the radius of holes in the cladding region and pitch distance, or distance between the centres of neighbouring holes, appropriately. The results from this work show that the electric field distribution is affected by mode coupling between the outer and inner modes; the effects of mode coupling of the PCF on the relative sensitivity were also determined.