Plasmonic Nanoantennas to Exploit Extraordinary Optical Transmission in Biosensing

In this research work, a plasmonic structure with a metallic nanoantenna is designed to work as a biosensor to monitor refractive index variation between 1.30, 1.33 and 1.35. The main goal is to compare the optical device response considering two different metals (gold and silver) and to analyse the hypothesis of designing biosensors based on the Extraordinary Optical Transmission effect, and due to the propagation of Surface Plasmon Polaritons. An oriented-object program is developed in Python to implement a novel model based on generalised Fresnel Coefficients and wave-particle dualism. This novel model brings geometrical intuition to complex electromagnetic problems and taking advantage of that, sensors are designed at nano-scale and femtoseconds orders. The obtained results allow us to conclude about the proposed goals. Even though a higher peak intensity is obtained with the silver structure, it is very selective and not sensitive. The gold structure, within this analyte’s refractive index range, presents sensitivities around 30%/RIU. The structure is able to respond to the stimulus between 6-7 fs. Thus, it is concluded that Extraordinary Optical Transmission is a novel degree of freedom to design nanosensors.