In this work we show that the insertion of a dielectric layer in Au/Co/Au magnetoplasmonic nanodisks fabricated by hole
mask colloidal lithography makes it possible to obtain systems that simultaneously exhibit large magneto-optical (MO)
activity and low optical extinction. The physical mechanism underlying this effect is the internal EM field redistribution,
in such a way to concentrate it in the MO active layer (Co) and, at the same time, reduce it in the non MO active
elements. We have performed a systematic study of the optical and MO response upon the variation of the Co layer
thickness within the nanodisk, finding an increase of the MO response with the increment of thickness, accompanied
with a blue shift and broadening of the peaks associated with the plasmon excitations.
Surface plasmon based photonic devices are promising candidates for highly integrated optics. An important effort in the
development of these devices is dedicated to the design of systems allowing the two dimensional control of surface
plasmon (SPP) propagation. Recently, it has been shown that Bragg mirrors consisting of gratings of metallic lines or
indentations on a metallic surface are very efficient tools to perform this task. Alternatively, using structured dielectric
layers on top of the metallic layer to build SPP optical elements based on the effective refractive index contrast has been
lately demonstrated. This kind of elements relies on the same principles as conventional optical elements. Here we
analyze the ability of gratings of dielectric ridges deposited on a metallic layer to act as dielectric SPP Bragg mirrors.
The dispersion relation of these systems shows the presence of a gap whose position can be approximately predicted by
the same relation as for standard optical Bragg mirrors. The properties of these dielectric based SPP Bragg mirrors have
been examined as a function of several structural grating parameters. The obtained results have been experimentally
confirmed by means of Fourier plane leakage radiation microscopy.