Resonancia de plasmones de superficie en sistemas films metálicos.

Abstract

The measurement of optical reflectivity allows to me characterizing surface plasmon resonances in flat or nanostructured metallic systems. In this work I have done a study of the resonance of propagating surface plasmons in metallic film systems wascarried out. Au y Ag, in which I have used the optical configuration of Kretschmann. Where noble metals are used for convenience (Au or Ag), due to the resonance of these plasmons is in the visible region of the electromagnetic spectrum, which facilitates these resonance processes. Analytical expressions of the theoretical models proposed in the literature were analyzed, including the Lorentz y Drude models. Therefore, from these models, the classical solution for the movement of the electron in a material was approached, from which the dielectric function is obtained, which allows inferring the optical behavior of the metal in terms of normal and anomalous dispersion (resonance). It is good to say that it has also been demonstrated in the Fresnel equations for optical reflectivity and they were simulated by implementing the codes in the Matlab program. It is very important to consider that from these simulations it has been possible to verify that the resonance of propagating surface plasmons depends on several parameters such as: the wavelength and polarization of the incident light, the angle of incidence, the refractive index of the dielectric medium that interacts with metal and the thickness of metal film. The sensitivity of the Kretschmann optical configuration to variations in the refractive index of the dielectric medium in contact with the metal was studied, denoting that the minimum variations in the refractive index are sufficient to generate angular shift of the plasmonic resonance peak. This angular shift made it possible to establish the operating principle of an optical sensor considering variations in the refractive index of aqueous solutions and gaseous.