When dealing with optics, the increasing level of understanding of a given problem relies on a good description of the behavior of the light in that optical system. In general, a numerical model should be devised, based on experimental evidences, in order to account for the specific problem under study. Approximations, such as ignoring polarisation effects and simplified descriptions of the light interacting with matter do provide important insights, but in general must be replaced by a fully electromagnetic description by means of the Maxwell’s equations. The Super-RENS effect, within this context, should be also studied in such rigorous manner. In other words, it is necessary to devise a numerical model for the Super-RENS effect, based on experimental evidences, that accounts for the problem. In this thesis, we are mainly interest in investigating the Super-RENS focused spot. Specifically, we study theoretically and experimentally the focused spot obtained by using a so called scatterer-type Super-RENS sample. Specifically, we study theoretically and experimentally the focused spot generated by a scatterer type of Super-RENS effect. Furthermore, we extend the numerical model to account for different types of Super-RENS materials. The tools used for the Super-RENS study, either experimental and theoretical, are also applied to investigate an immersed focused spot generated by micro-sized solid immersion lenses. In summary, we start with a discussion on the Super-RENS effect, directly applied to the readout of optical discs, applying a scalar diffraction theory. This theory is presented together with a simplified model for the Super-RENS effect. The readout of the Super-RENS focused spots is presented and the results are compared with available published data. An explanation for the possible cause for readout beyond the diffraction limit is also given. The limitations inherent to the scalar approximation compelled us to develop a more sophisticated model for the Super-RENS effect. This model is based on the fully vectorial description of the light interacting with matter. The predictions of the rigorous model are compared with the scalar results. To validate the numerical model, we compare its predictions with an experimental counterpart. We directly measured the super resolved focused spot in the near field regime as it leaves an active Super-RENS stack layer, and present the results along with a detailed explanation of the experimental setup used to obtain them. An extraordinary agreement is found between measurements and simulations. Because of that, the rigorous threshold model is used to study the near-field properties of the Super-RENS spot in detail. Aside for Indium antimonide (InSb), this is done for the aperture type of super resolution material as well. The readout problem is again studied, but this time using the rigorously computed Super-RENS spot as input for the scalar readout algorithm. Finally, we show a different approach to take advantage of the scatterer being generated in the active layer in order to achieve super resolved spots at high numerical apertures. To broaden the scope of the thesis, we use the tools developed throughout the initial chapters to study several other applications of interest, mainly regarding solid immersion lens. An introduction to the solid immersion technique is given. A rigorous numerical model is presented to simulate the light interacting with tiny SILs and the immersed spot is experimentally measured in the near-field regime using the measuring techniques described in the experimental section. A deeper study on the immersion effect is presented for a variety of polarized beams, including the “doughnut spot” generated by focusing an azimuthally polarized laser beam onto a 2?m-SIL. Furthermore, we present a study on the misalignment tolerance of the 2?m-SIL immersing doughnut and two-half-lobe spots. Finally, we propose an alternative method for generating a doughnut-like focused spot that does not rely on changing the laser polarization. We also include five appendices to complement the description of the methods used in this thesis. The possible mechanisms that lead to the non-linear behaviour of the InSb, when exposed to high intensity laser light, are briefly discussed based on the available literature. An analytical model for the scalar super-resolution effect is presented. The Super-RENS focused spots generated at small numerical apertures are experimentally investigated to further test the threshold model. An analytical method to obtain the focused spot for high numerical aperture lenses is provided in detail. Finally, an introduction to the Finite Element Method (FEM) programming, useful to understand the basic concepts of a FEM program, is given. In conclusion, we have discussed a set of advanced techniques to accurately describe the electromagnetic field in the Super-RENS effect. From the discussion of these techniques, a thorough fundamental understanding of the problem is obtained. Moreover, the experimental approach adopted serves to study not only this particular problem, but also many other advanced near-field problems. Hence, this work establishes the basic background for numerical and experimental characterization of advanced optical systems in the near-field regime.