Electromagnetic behavior of plasmonic devices with nanoholes. Biosensing applications
ABSTRACT: Development of nanotechnology in the last decades has allowed the knowledge and experimental exploration of new physical phenomena to nanometric scale. Concretely, in nanophotonics field, the interaction of light with matter to such small scale has provided interesting applications in medi...
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| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2014 |
| País: | España |
| Institución: | Universidad de Cantabria (UC) |
| Repositorio: | UCrea Repositorio Abierto de la Universidad de Cantabria |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.unican.es:10902/5599 |
| Acceso en línea: | http://hdl.handle.net/10902/5599 |
| Access Level: | acceso abierto |
| Palabra clave: | Plasmonic Surface plasmons Extraordinary Optical Transmission Rayleigh anomaly Finite Element Method (FEM) COMSOL Plasmónica Plasmones superficiales Transmisión Óptica Extraordinaria Anomalía de Rayleigh Método de Elementos Finitos (FEM) |
| Sumario: | ABSTRACT: Development of nanotechnology in the last decades has allowed the knowledge and experimental exploration of new physical phenomena to nanometric scale. Concretely, in nanophotonics field, the interaction of light with matter to such small scale has provided interesting applications in medicine, physics, biology, materials… Paying attention to the development of biosensors, it is found as their sensitivity can increase by using nanohole arrays perforated in metallic thin films. This fact is based on Extraordinary Optical Transmission (EOT). Since its discovery by Ebbesen et al. in 1998 much effort has been realized with the objective of reaching high values of the sensitivity. When nanoholes, which are distributed periodically, are illuminated by wavelengths greater than the nanohole aperture and than the distance between them, in the transmission spectrum, different resonances are observed for some concrete wavelengths. These take place due to the interaction between surface plasmons at both dielectric-metal interfaces of the nanohole array. In this project, using as numerical method: Finite Element Method (FEM) implemented in the commercial software COMSOL, we have simulated different geometries. All of them are constituted by a thin metallic film where nanoholes are perforated, located on a dielectric substrate, in order to design a biosensor easy to manufacture and with a high sensitivity (high variation of the peaks in the transmission spectrum due to changes in the buffer optics constants). In all the simulated biosensors, nanohole array was perforated in a gold thin film, the diameter of nanoapertures was 180nm and the period (distance between two consecutive nanoholes) was 500nm. The thickness of the thin film was changed along the project. During the project we paid special attention to a concrete configuration, which consists of a Fabry-Perot nanocavity set under the nanohole array, due to the high sensitivity to changes in the buffer refractive index that this nanostructure presents, when buffer is introduced inside the nanocavity. The sensitivity for the different nanostructures considered was obtained through the peaks spectral shift observed in the ransmission/reflection spectra as a function of the changes in the buffer refractive index, Δλ/Δn. |
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