English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/61718
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL | DATACITE
Exportar a otros formatos:


Dynamics of plasma formation, relaxation, and topography modification induced by femtosecond laser pulses in crystalline and amorphous dielectrics

AuthorsPuerto, D. CSIC ORCID; Siegel, Jan CSIC ORCID ; Gawelda, W.; Galván Sosa, M.; Ehrentraut, L.; Bonse, J. CSIC ORCID; Solís Céspedes, Javier CSIC ORCID
Issue Date2010
PublisherOptical Society of America
CitationJournal of the Optical Society of America B: Optical Physics 27: 1065- 1076 (2010)
AbstractWe have studied plasma formation and relaxation dynamics along with the corresponding topography modifications in fused silica and sapphire induced by single femtosecond laser pulses (800 nm and 120 fs). These materials, representative of high bandgap amorphous and crystalline dielectrics, respectively, require nonlinear mechanisms to absorb the laser light. The study employed a femtosecond time-resolved microscopy technique that allows obtaining reflectivity and transmission images of the material surface at well-defined temporal delays after the arrival of the pump pulse which excites the dielectric material. The transient evolution of the free-electron plasma formed can be followed by combining the time-resolved optical data with a Drude model to estimate transient electron densities and skin depths. The temporal evolution of the optical properties is very similar in both materials within the first few hundred picoseconds, including the formation of a high reflectivity ring at about 7 ps. In contrast, at longer delays (100 ps-20 ns) the behavior of both materials differs significantly, revealing a longer lasting ablation process in sapphire. Moreover, transient images of sapphire show a concentric ring pattern surrounding the ablation crater, which is not observed in fused silica. We attribute this phenomenon to optical diffraction at a transient elevation of the ejected molten material at the crater border. On the other hand, the final topography of the ablation crater is radically different for each material. While in fused silica a relatively smooth crater with two distinct regimes is observed, sapphire shows much steeper crater walls, surrounded by a weak depression along with cracks in the material surface. These differences are explained in terms of the most relevant thermal and mechanical properties of the material. Despite these differences the maximum crater depth is comparable in both material at the highest fluences used (16 J/cm2). The evolution of the crater depth as a function of fluence can be described taking into account the individual bandgap of each material. © 2010 Optical Society of America.
Identifiersdoi: 10.1364/JOSAB.27.001065
issn: 0740-3224
Appears in Collections:(CFMAC-IO) Artículos
Files in This Item:
File Description SizeFormat 
Puerto.pdf827,73 kBAdobe PDFThumbnail
Show full item record
Review this work

Related articles:

WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.