Modelling of nanoantenna-based optical sensors for high-sensitivity high-resolution infrared spectroscopy of chemical compounds

In this paper we investigate how to increase the functionalities of optical sensors based on metal nanoantennas (NA) arranged in 2D-arrays as sensitive spectroscopic tools for the identification of molecular species by using the Surface Enhanced InfraRed Absorption (SEIRA) technique. We will discuss the influence of the NA geometrical parameters (length, width and thickness) and 2D-array periodicity on the local electric field enhancement and 2D-array spectral response. Software based on the finite element method (FEM) is used to accurately simulate the NA 2D-array reflectivity response as a function of the wavelength of the probing light. In particular, by evaluating the optical response of rod and cross NA 2D-arrays we studied the influence of the NA geometrical parameters on the SEIRA response.