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Proceedings Paper

Pump-probe investigation of fs-LIOB in water by simultaneous spatial and temporal focusing
Author(s): Robert Kammel; Roland Ackermann; Andreas Tünnermann; Stefan Nolte
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Paper Abstract

Femtosecond lasers are a versatile tool to process transparent materials like glasses, polymers or ophthalmic tissue. However, when focusing pulses of several μJ into the material, the high intensity near the laser focus leads to undesired nonlinear side effects like self-focusing and filamentation, resulting in an increased length of the induced plasma or the fragmentation of the breakdown volume. To overcome this limitation, we studied the influence of simultaneous spatial and temporal focusing (SSTF) on the laser induced optical breakdown (LIOB) in water. For this purpose, the incoming laser pulse is spectrally separated by a grating stretcher setup and recompressed by the focusing optics. Due to the increased pulse duration outside of the laser focus, the nonlinear laser-material interaction is confined to the focal region. We investigated the formation of the plasma and the resulting disruption in water by shadow imaging. With conventional focusing (τ = 70 fs, NA = 0.1) self-focusing, filamentation and breakup of the disruption volume was observed for pulse energies > 2 μJ, leading to a breakdown length of ~ 800 μm at a pulse energy of 8 μJ. With SSTF the axial length of the breakdown is significantly reduced by a factor of ~ 2. Plasma formation and the resulting disruption stay within the focal region. No self-focusing could be observed for pulse energies up to 8 μJ. Therefore, SSTF appears to be a promising tool to induce photodisruptions in transparent materials even with low numerical aperture, e.g. for precise fs-laser surgery within the posterior segment of the eye.

Paper Details

Date Published: 15 March 2013
PDF: 7 pages
Proc. SPIE 8611, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIII, 86110A (15 March 2013); doi: 10.1117/12.2006169
Show Author Affiliations
Robert Kammel, Friedrich-Schiller-Univ. Jena (Germany)
Roland Ackermann, Friedrich-Schiller-Univ. Jena (Germany)
Andreas Tünnermann, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
Stefan Nolte, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)


Published in SPIE Proceedings Vol. 8611:
Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIII
Alexander Heisterkamp; Peter R. Herman; Michel Meunier; Stefan Nolte, Editor(s)

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