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Periodic nanostructure arrays forming electric dipoles or quadrupoles were fabricated with a Focused Gallium Ion Beam on a gold thin film deposited onto an Er3+-doped tellurite glass. The nanostructures were vertically illuminated with an Argon Ion laser (488 nm). The Er3+luminescence spectrum was then measured in the far-field. The observed luminescence is elucidated considering the following effects: (i) excitation of the Er3+ions by means of the localized surface plasmon resonance from the electric dipole/quadrupole nanostructures, that produce an improvement of the local field, resulting in an enhanced luminescence, and (ii) the Er3+luminescence spectrum depends on the albedo of the system (electric dipole/quadrupole arrays), for which its resonant properties is strongly affected. In this way, the emission of the Er3+is achieved through the metallic nanostructures. Additional contributions for the observed emission spectrum regarding the influence of physical and geometrical parameters, period of the electric multipole and lattice symmetry have been investigated. The variation of these parameters resulted in a significantly improvement of luminescence spectra.

Plasmonic lenses consisting of convex/concave concentric rings with different periods were milled with a Focused Gallium Ion Beam on a gold thin film deposited onto an Er3+-doped tellurite glass. The plasmonic lenses were vertically illuminated with an Argon Ion laser (488 nm) highly focused by means of a 20x objective lens. The focusing mechanism of the plasmonic lenses is explained by using a simple coherent interference model of surface plasmon-polariton generation on the circular grating as a result of the incident field. Particularly, this beam focusing structure has a modulated groove depth (concave/convex). As a result, phase modulation can be accomplished by the groove depth profile, similarly to a nano-slit array with different thicknesses. This focusing allows a high confinement of SPPs which excited the Er3+ions of the substrate. The luminescence spectrum of Er3+ions was then measured in the far-field, where we could verify the excitation yield of the plasmonic lens on the Er3+ions. We analyze the influence of physical and geometrical parameters on the emission spectra, such as the periodicity and depth profile of the rings. The variation of these parameters resulted in considerable changes of the luminescence spectra.

We report the 3D simulation of a disk-shaped, Moiré-type plasmonic cavity inside a photonic crystal cavity. The simulation consider normal incidence of light over the sample to be analized with a confocal microscope in reflection mode. The plasmonic cavity is made of gold, 250 nm of thickness, whose surface is modulated by a sinusoidal function. The photonic crystal cavity is made in silicon nitride film (150 nm of thickness) over a SiO2 film (500 nm) on a silicon substrate, the overall structure being Si/SiO2/SiN/Au. The simulation results show a three-fold enhancement of the electric field intensity for the plasmonic cavity within the photonic cavity, in comparison with that for the plasmonic cavity without the photonic crystal cavity. The result indicates that the electric field intensities of the photonic crystal cavity modes add to the scattered field of the plasmonic cavity, thus enhancing the electric field just above the plasmonic cavity. A preliminary test of the structure was done with a 300 nm gold film over a silicon substrate, made by focus ion beam (FIB) milling, to show fluorescence enhancement of porphiryn molecules. The structure can be elaborated to serve either as fluorescence enhancement of molecules or as Surface-enhancement Raman scattering (SERS) sensor.

Multilayered Ag/Au/Ag/Au and Au/Ag/Au/Ag films with 200 nm of thickness (50 nm for each layer) were evaporated onto BK7 glass substrates. Sequences of slits (around 60-600 nm of width) were milled with a focused gallium ion beam in the films. We have undertaken a series of high-resolution measurements of the optical transmission through the slits. The transmission measurement setup consists of 488.0 nm (for the Ag/Au/Ag/Au film) and 632.8 nm (for the Au/Ag/Au/Ag sample) wavelength light beams from Ar ion and HeNe lasers, respectively, aligned to the optical axis of a microscope. The beam is focused onto the sample surface by a microscope objective in TM polarization (magnetic Hfield component parallel to the long axis of the slits). As well, theoretical estimates investigating the slits optical transmission were performed. The origin of the slits transmission is mainly attributed to plasmonic surface excitations. Based on the present results, it was possible to observe that (1) the transmission increases linearly with increasing slit width, and (2) the transmission of the multilayered structures is augmented in comparison with a single perforated metal film of equal thickness, for a fixed slit width. A very good correspondence between theory and experiment was observed.