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The most common approach in standard nanoplasmonics for the analysis of the resonant behavior of light interaction with these nanostructures has been the application of the local-response approximation (LRA), using – depending on the structure complexity and relation between a characteristic dimension and the interacting wavelength – either (quasi)analytic or numerical approaches. Recently, however, as the characteristic dimensions of such structures have scaled down, it has turned out that more complex models based on the nonlocal response (NOR), or even quantum interaction are required for explaining novel effects, e.g. blue spectral shifts, etc. This fact has lately started a rapid increase of interest in developing appropriate nonlocal models. In particular, in our studies, we have concentrated on understanding the interaction and developing a simple model capable of predicting the longitudinal nonlocal response based on the linearized hydrodynamic model, generalizing the standard Abajo’s nonlocal model. Our model is applicable to simple structures, such as a spherical nanoparticle. Within our model, we have also shown and compared several alternatives within the approach, with respect to inclusion of the current “damping”. As the most promising approach, we have found the approach incorporating both radiative and viscosive damping. Here, we have considered the Landau damping, too. We have demonstrated the applicability of our extended model on comparing the extinction cross section predictions of both gold and silver spherical nanoparticles. Using this model, we have systematically studied the relevant components of the electric fields and electric current densities, with respect to nanoparticles immersed in dielectric surrounding media (such as air or water). In parallel, we have also looked at the multilayer system with a general combination of local and nonlocal layers, in terms of overall transmission and reflective properties. Our results of the analysis will be also shown. Next, as an alternative (and more general) approach, based on our previous rich experience with Fourier modal methods, we have considered and developed the extension of the rigorous coupled wave analysis technique capable of treating nonlocal response numerically, for more general structures. Also, moving to even smaller characteristic dimensions of studied nanostructures, we have also adopted within our numerical techniques the Quantum corrected model, to estimate the corrections on spectral cross-section dependences, due to quantum electron tunneling effects.
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