Multi-physical modeling of laser nano- and micro-structuring of glasses

Laser nano- and microstructuring of glasses attracts constantly growing interest due to numerous applications mainly in such fields as optics, photonics, and nano-fluidics. Numerous experiments have demonstrated possibilities of laser-induced structuring both in volume and at the surface with reduced resolution. In addition, both well-controlled and spontaneously formed periodic self-organized structures were often obtained, while their origin remained unclear. In this study, we focus our attention on the laser-triggered material response that we investigate as a function of both laser parameters and material properties. For this, multi-physical approach is applied and a combined model is developed [1-2]. The model accounts for such effects as laser-induced modifications and mechanisms of glass decomposition in fused silica are numerically investigated. Cavitation is shown to be the primary mechanism responsible for void formation within the heat-affected zone. It is demonstrated, furthermore, that multi-pulse accumulation processes providing higher local temperatures/pressures lead to the rapid cavitation or nanopores formation, lying in the origin of self-organized nanogratings. Laser thresholds required for nanogratings formation/erasure are defined in agreement with the available experimental findings. Additionally, we consider weaker laser interaction regimes with porous materials containing ions and nanoparticles. In this case, nanoparticle distributions are shown to define to a large extend not only material absorption properties that can evolve both in time and space, but also material temperature. Again, a detailed 3D modeling allows us to elucidate the main driving mechanisms of the final structure formation and provide the optimization ways for this processing. [1] A. Rudenko, H. Ma, V. P. Veiko, J.Ph. Colombier, T. E. Itina (2017) On the role of nanopore formation and evolution in multi-pulse laser nanostructuring of glasses. Applied Physics A. 124: 63. https://doi.org/10.1007/s00339-017-1492-2 [2] A. Rudenko; J-Ph. Colombier, T.E. Itina (2017) Nanopore-mediated ultrashort laser-induced formation and erasure of volume nanogratings in glass, Phys. Chem. Chem.Phys., 2018 Feb 21;20(8):5887-5899. doi: 10.1039/c7cp07603g.. [3] M. Lancry, B. Poumellec, J. Canning, K. Cook, J.-C. Poulin, F. Brisset (2013) Ultrafast nanoporous silica formation driven by femtosecond laser irradiation, Laser & Photonics Review 7(6), 953–962.