## 4 Performance and Framework
Along the photoexcitation path, the maximum power occurs around the metal- fused silica interface, enhancing and localizing the light coupling to the nanocomposite material. Even if the non-diffractive behavior is still present, it is less observable, as the beam is strongly attenuated by metal absorption. Moreover, the arrangement of the higher region of light absorption follows the randomly distributed composition of the metallic sphere. This indicates that contrary to dielectric-void interfaces, the dielectric-metal region fosters local  
Figure 7: (**a**) Computational domain including clusters of spherical nanovoids, randomly located inside the fused silica bulk. (**b**) Power history of the pulsed Bessel beam propagating inside the nanoporous block. (**c**) History of the photo-ionized electrons density in the complete domain. effects, preventing any collective response of the medium. This statement may differ if the particles are judiciously defined in terms of concentration and size in order to enhance resonance effects as plasmonic modes. In Figure 9, we observe a pattern in the electron photoionized history. In particular, Figure 9a depicts a weak structure of parallel planes, which is more intense in some regions. Figure 9b shows a stronger pattern. The present results, sketched by Figure 9a, reveal that ultrashort laser pulse interacting with distributed performed scattering nanovoids induces local field enhancement that results in enhanced nonlinear absorption and localized optical breakdown. At the void-SiO\({}_{2}\) interface, the multiphotonic ionization process transforms the material into a thin layer of absorbing plasma with metallic-like properties. The light coupling initiates the growth of nanoplates of enhanced energy deposition, perpendicular to laser propagation direction, but parallel to the polarization. This kind of arranged structure exhibiting a periodicity approximately the wavelength of light in fused silica was commonly experimentally reported in conditions of tightly focused and high repetition rate [32; 33]. They directly emerge from the spatial coherence of the waves scattered from the inhomogeneous material in the plane perpendicular to the beam propagation direction. Note the relatively used large nanovoids associated to the grid resolution do not allow to discriminate nanogratings of higher frequency perpendicular to the electric field. For propagation inside laser-induced nanoporous media, the fused silica glass remains underdense, below the critical plasma concentration, and the standing wave effect remains weak. However, the other simulation conditions, portrayed in Figure 9b), clearly indicate that for metallic nanoparticles, local field enhancement occurs near the metal-dielectric interface [34]. Upon electron-matrix energy coupling and void deformation, the light pattern may result in elongated nanostructures [35]. This shows that nanoplasmonic behavior dominates and opens the route for advanced applications as embedded micro-reflectors for a stronger near-field interaction regime. Figure 8: (**a**) Power history of the pulsed Bessel beam propagating inside the fused silica block in which we place a cluster of spherical metal particles. (**b**) History of the photo-ionized electrons density in the complete domain. Propagation and scattering through sphere inclusions with different optical properties demonstrate that the current algorithms are stable and can model efficiently nonlinear media with sharp dielectric interfaces among them. Moreover, nonlinear metal-dielectric interface investigations are far reaching for technology-based photonics. For instance, in a wider frequency spectrum, resonators, metasurfaces with designed cavities, metal-dielectric waveguides or even coating optical fibers are composed of metal-dielectric interfaces that may involve simultaneously nonlinear mechanisms of different nature.