Computer simulation, fabrication and characterization of inverse frustum nanosphere metal arrays for fiber-based plasmonic sensors

In recent years, a number of metal nanostructures have attracted huge attention from scientists and researchers for its plasmonic property and surface enhanced Raman scattering effect. They have been utilized to monitor molecule adsorption, antibody-antigen reorganization event, and to enhance scattering for identification of molecules even in very low concentration. They both have also been exploited for real time biosensing.;In this thesis, we are investigating a new plasmonic structure, inverse frustum nanosphere gold arrays, and exploring its optical fiber-based sensing application. The nanostructure was fabricated by electro-deposition of gold into pre-assembled templates, which are made of monodispered colloidal polystyrene nanospheres in a hexagonal close packing structure. The structure is further modified by introducing circular bottom hole to each hemispherical void for optical fiber-based probe application. Its plasmonic sensing behavior is demonstrated. The effect of structure parameters, such as gold film thickness and bottom hole diameter on LSPR is symmetrically studied in both experiments and simulations. The advantage of this structure against lithographically patterned cylindrical hole arrays is displayed and its potential application as molecule adsorption monitor is predicted and tested.