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Welding of transparent materials with ultrashort laser pulses

 
: Richter, Sören; Döring, Sven; Zimmermann, Felix; Lescieux, Ludovic; Eberhardt, Ramona; Nolte, Stefan; Tünnermann, Andreas

:

Bachmann, F.G. (Ed.) ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Laser-based Micro- and Nanopackaging and Assembly VI : San Francisco, California, USA, January 2012
Bellingham, WA: SPIE, 2012 (Proceedings of SPIE 8244)
ISBN: 978-0-8194-8887-9
Paper 824402
Conference "Laser-Based Micro- and Nanopackaging and Assembly" <6, 2012, San Francisco/Calif.>
English
Conference Paper
Fraunhofer IOF ()
welding; femtosecond laser materials processing; high repetition rate; fused silica

Abstract
The realization of stable bonds between different glasses has attracted a lot interest in recent years. However, conventional bonding techniques are often problematic due to required thermal annealing steps which may lead to induced stress, whereas glue and other adhesives tend to degrade over time. These problems can be overcome by using ultrashort laser pulses. When focussed at the interface, the laser energy is deposited locally in the focal volume due to nonlinear absorption processes. While even single pulses can lead to the formation of bonds between transparent glass substrates, the application of high repetition rates offers an additional degree of freedom. If the time between two pulses is shorter than the time required for heat diffusion out of the focal volume, heat accumulation of successive pulses leads to localized melting at the interface. The subsequent resolidification finally yields strong and robust bonds. Using optimized processing parameters, we achieved a breaking strength up 95% of the pristine bulk material. In this paper, we will detail the experimental background and the influence of the laser parameters on the achievable breaking strength.

: http://publica.fraunhofer.de/documents/N-195824.html