Plasmonic nano bow-tie arrays with enhanced LSPR refractive index sensing

Abstract

In this work, the performance of the nano bow-tie arrays for biosensing applications has been investigated. Since the geometrical parameters of the device such as the bow-tie length and gap size have major effects on the system's optical response, a parametric study based on finite-difference time-domain (FDTD) method has been conducted. In order to enhance the sensitivity, two bow-tie shaped nanoparticles in the form of 2 × 1 and 2 × 2 arrays have been developed. In the case of TM polarisation, a sensitivity up to 923 nm/RIU with a figure of merit (FOM) of 5.5 has been obtained for 2 × 2 nano bow-tie array. Moreover, the performance of the proposed nanoparticles for TE polarisation has been evaluated and a FOM exceeding 15.9 has been achieved for single nano bow-tie. According to this study, the proposed nano bow-tie structures have a great potential for sensing and detection applications.