FLASH Projet

The first axis focuses on modeling electronic photoexcitation using Density Functional Theory (DFT). This approach enables the description of electronic structure dynamics under ultrashort pulses. A Maxwell-Bloch-type approach incorporating this excited band structure will be used to calculate transition dipole moments specific to each material. The ultrafast, nonlinear material
responses thus obtained will then provide optical coupling data for the other axes of the project. The other two axes will be highly complementary: the second targets the anisotropic growth of photoinduced nanopores in a multi-pulse regime (Type II – intermediate intensity), while the third addresses the influence of transiently formed (Type III, high intensity) or preexisting microporosities to achieve a multi-scale understanding of effects related to heterogeneities

Axis 2 explores the inhomogeneous energy deposition in dielectric materials at the nanoscale, focusing on nanoporosity effects. Laser absorption generates thermal gradients that alter the structure and local optical indices. Using space- and time-resolved electromagnetic simulations, the absorbed energy distributions will serve as a basis for evaluating structural effects, polymorphic phase transitions, and nanoscale structuring. This axis examines organized nanometric patterns (birefringence and polymorphism) with potential applications in nanoscale information storage.

Axis 3 concentrates on laser-matter interaction at higher intensity, analyzing the dynamic responses induced by the high pressures generated in the focal area where micropores appear. Coupled models of propagative optics and fluid dynamics will be used to study thermomechanical relaxation phenomena, revealing the response of structured materials under extreme constraints. By integrating effects at different scales, this axis aims to simulate the propagation, diffusion, and attenuation of shock waves based on pore density, size, and geometry. This approach will improve the understanding of deformation mechanisms in porous structures, their effects on material relaxation dynamics, and ultimately assess the mechanical strength of pre-structured materials.