Metallic nanostructures supporting Localized Surface Plasmon Resonances (LSPR) are characterized by their unique ability to control and manipulate light at the nanoscale. Noble metal nanostructures, such as gold nanostructures, are demonstrating to exhibit magneto-optic activity in the presence of modulated magnetic field of low intensity in transversal configuration (T-MOKE). Validation of experimental findings was achieved by numerical simulations based on Finite Element Method (FEM) techniques. The developed numerical models allowed studying the combination of the T-MOKE effect with the localized surface plasmon resonance of metal nanoparticles. Numerical optical and magneto-optical spectra provided a deep insight on the physical aspects behind the magneto-optical activity of metal nanostructures strictly related to direction of oscillations electrical dipoles generated in resonance conditions. Additionally the MO signal was characterized as a transducing signal for refractive index sensing in liquid conditions. The outcome is an increase in the limit of detection of magneto optical transducer with respect to traditional plasmonic sensors. A new strategy for magneto-plasmonic sensing based on the use of glass supported -Au nanostructures based on their MO properties has put forward.

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The sensing performance comparisons presented in this work were carried out by exploiting a suitable magneto-plasmonic sensor in both the traditional surface plasmon resonance configuration and the innovative magneto-optic surface plasmon resonance one. The particular multilayer transducer was functionalized with TiO2 Brookite nanorods layers deposited by matrix assisted pulsed laser evaporation, and its sensing capabilities were monitored in a controlled atmosphere towards different concentrations of volatile organic compounds mixed in dry air.

Unconventional lithography (such as nanosphere lithography (NSL) and colloidal lithography (CL)) is an attractive alternative to sequential and very expensive conventional lithography for the low-cost fabrication of large-area nano-optical devices. Among these, nanohole (NH) arrays are widely studied in nanoplasmonics as transducers for sensing applications. In this work, both NSL and CL are implemented to fabricate two-dimensional distributions of gold NHs. In the case of NSL, highly ordered arrays of gold NHs distributed in a hexagonal lattice onto glass substrates were fabricated by a simple and reproducible approach based on the self-assembling of close-packed 500 nm diameter polystyrene particles at an air/water interface. After the transfer onto a solid substrate, the colloidal masks were processed to reduce the colloidal size in a controllable way. In parallel, CL was implemented with short-range ordered gold NH arrays onto glass substrates that were fabricated by electrostatically-driven self-assembly of negatively charged colloids onto a polydiallyldimethylammonium (PDDA) monolayer. These distributions were optimized as a function of the colloidal adsorption time. For both approaches, controllable and reproducible procedures are presented and discussed. The optical responses of the NH structures are related to the short-range ordering level, and their good performances as refractive index transducers are demonstrated.

Tailoring the optical response of metal nanoparticles by controlling their morphology is a key topic in the field of nano-optics. Here, a simple approach for the fabrication of tunable plasmonic nanostructures by nanosphere lithography is presented.