title: Nanofabrication of tailored surface structures in dielectrics using temporally shaped femtosecond-laser pulses.
abstract: We have investigated the use of tightly focused, temporally shaped femtosecond (fs)-laser pulses for producing nanostructures in two dielectric materials (sapphire and phosphate glass) with different characteristics in their response to pulsed laser radiation. For this purpose, laser pulses shaped by third-order dispersion (TOD) were used to generate temporally asymmetric excitation pulses, leading to the single-step production of subwavelength ablative and subablative surface structures. When compared to previous works on the interaction of tightly focused TOD-shaped pulses with fused silica, we show here that this approach leads to very different nanostructure morphologies, namely, clean nanopits without debris surrounding the crater in sapphire and well-outlined nanobumps and nanovolcanoes in phosphate glass. Although in sapphire the debris-free processing is associated with the much lower viscosity of the melt compared to fused silica, nanobump formation in phosphate glass is caused by material network expansion (swelling) upon resolidification below the ablation threshold. The formation of nanovolcanoes is a consequence of the combined effect of material network expansion and ablation occurring in the periphery and central part of the irradiated region, respectively. It is shown that the induced morphologies can be efficiently controlled by modulating the TOD coefficient of the temporally shaped pulses.
authors.forename: Javier
authors.initials: J
authors.lastname: Hernandez-Rueda
authors.affiliation: §Institut für Physik, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Götte
authors.forename: Jan
authors.initials: J
authors.lastname: Siegel
authors.forename: Michelina
authors.initials: M
authors.lastname: Soccio
authors.affiliation: §Institut für Physik, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Zielinski
authors.affiliation: §Institut für Physik, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.
authors.forename: Cristian
authors.initials: C
authors.lastname: Sarpe
authors.affiliation: §Institut für Physik, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.|∥Carl von Ossietzky Universität Oldenburg, Institut für Physik, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wollenhaupt
authors.forename: Tiberio A
authors.initials: TA
authors.lastname: Ezquerra
authors.affiliation: §Institut für Physik, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Baumert
authors.forename: Javier
authors.initials: J
authors.lastname: Solis
keywords: dielectrics; femtosecond lasers; nanofabrication; phosphate glass; sapphire; temporal pulse shaping