Ultra-short laser processing of optical materials: can random inhomogeneities, nanoholes or nanoparticles be seeds of periodic volume nanostructutres ?
Résumé
Ultrashort lasers are used for a wide range of micro- and nanomachining applications of different materials. The most promising of them include the formation of 3D nanostructures inside glasses, surface and volume periodic nanostructrures and ultra-short laser interactions with composites and metamaterials. For further development of these applications, detailed 3D numerical models are required combining both simulation of light propagation effects and the following laser-induced material excitation and modification. Some of these processes occur simultaneously (i. e., propagation and ionization), whereas other are much longer (thermal-mechanical effects) and can be taken into account separately. In this paper, several potential applications of bulk laser-induced plasmas ranging from Bessel beam-induced long laser channel formation to laser-induced volume nanograting formation are analyzed.
It is demonstrated that light propagation dynamics considerably affects femtosecond laser treatment of transparent materials. In particular, volume nanograting formation induced by femtosecond laser irradiation of fused silica with the presence of randomly distributed nanometric defects, such as holes or nanoparticles, is investigated numerically [1-3]. The created nanoplasmas are shown to elongate perpendicular to the laser polarization direction with a period significantly smaller than the incident irradiation wavelength. The characteristics of these nanoplanes are found to depend strongly on the concentration of the initial defects and on the irradiation wavelength in a good agreement with several experimental observations.
References
[1] A. Rudenko, J-Ph. Colombier, T. E. Itina, From random inhomogeneities to periodic nanostructures induced in bulk silica by ultrashort laser, Phys. Rev. B, (2016) in press.
[2] A. Rudenko, J-Ph. Colombier, T. E. Itina, Femtosecond laser irradiation of dielectric materials containing randomly-arranged nanoparticles, SPIE LASE 2016, accepted (2016).
[3] A. Rudenko, J-Ph. Colombier, T. E. Itina, Femtosecond laser irradiation of fused silica with a nanometric inhomogeneity, PIERS Proceedings, 1652 - 1656, July 6-9, Prague, (2015).