Abstract
At the end of the XX century, a new phenomenon was discovered by Ebbesen, the extraordinary optical transmission. He reported that metallic arrays composed of nano holes, also called nanoantennas, can support resonant optical transmissions responsible by the amplification and concentration of electromagnetic radiation. Classical diffraction theories do not predict this extraordinary phenomenon. This article shows the timeline of theories that try to model the interaction between light and metal planes with slits, holes, grooves or apertures. The comparison between theories is done. Furthermore, as the optical response of these nanoantennas is dependent on the complex dielectric function, there is a high probability of successfully using these structures as sensors. This article aimed to verify how the structure parameters (periodicity, hole diameter, nanoantenna thickness and substrate thickness) can influence the optical response in order to tune the spectrum. Using a Finite Element Tool, several 3D simulations aim to conclude about the parameters influence on air–gold–quartz and air–aluminum–quartz structures, being the nanoantenna made with gold and aluminum. Moreover, all the simulations allow us to verify a resonant spectral response and the existence of great values of amplification near the metal surface. This is a clear evidence of a energy exchange due to the generation and propagation of surface plasmon polaritons. Based on the spectra taken from the parameter analysis, a specific structure was chosen to test two different sensors. A temperature sensor and a tissue detection sensor were tested and the simulations are presented. It is concluded that a nanostructure based on a nanoantenna can be used as a sensor for several applications.
Highlights
The interaction between electromagnetic waves, for instance light, and matter was always a topic that aroused interest to the scientific community [1,2,3,4]
The resonant behavior characteristic from extraordinary optical transmission (EOT) is affected by the complex dielectric function, which depends on the incident wavelength
This article will show the resonant behavior of the EOT, as well as the capability of amplify and concentrate electromagnetic radiation, for a metallic nanoantenna at frequencies on the visible and near-infrared spectral regions
Summary
The interaction between electromagnetic waves, for instance light, and matter was always a topic that aroused interest to the scientific community [1,2,3,4]. Because some phenomena were discovered recently, as the extraordinary optical transmission (EOT) and based on them it has been possible to develop new devices [1,2,5,6]. The complex dielectric function is often presented as a fitting of the Drude–Lorentz model, for each material [1,2,7,8]. The variation of the complex dielectric function with physical or chemical events can be useful to develop a sensor. This kind of sensors can be designed for many application in different fields such as medicine, chemistry, defense, communications, energy or environment [1,2,6]. This article aimed to analyze the parameter influence, but it presents simulations from two different sensor applications
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