  Here we propose a new computational approach to light-to-matter interactions
in silicon nanopillars, which simulates heat generation and propagation
dynamics occurring in continuous wave laser processing over a wide temporal
range (from 1 fs to about 25 hours). We show that visible light can be
exploited to selectively crystallize internal region of the pillars, which is
not possible by conventional treatments. A detailed study on lattice
crystallization and reconstruction dynamics reveals that local heating drives
the formation of secondary antennas embedded into the pillars, highlighting the
importance of taking into account the spatial and temporal evolution of the
optical properties of the material under irradiation. This approach can be
easily extended to many types of nanostructured materials and interfaces,
offering a unique computational tool for many applications involving
optothermal processes.
