Material processing by temporally shaped ultrashort pulses


Contact Person(s):
Dr. Panagiotis Loukakos


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Pulse Shaping based on a Spatial Light Modulator is employed in combination with ultrashort laser pulses for control and optimization of processing on solid state surfaces. First results on metals show the need to exploit temporal windows where electronic and lattice interactions are more prominent. Current work continues on metal oxides and semiconductor surfaces.

Research Topics
Ultrafast Condensed Phase Dynamics

Abstract

 

Ablation and processing of a material have been traditionally realized by using single bursts of energy delivered by laser pulses. Initially ns lasers have been employed but later on femtosecond (fs) laser-assisted ablation has proven to be more beneficial in terms of increased precision due to the reduction of heating effects.

              Lately, novel techniques allowing the manipulation of the temporal shape of fs laser pulses are being incorporated in the interaction of lasers with matter. The interest here is twofold: Firstly, to investigate the possibility of controlling the processing of a surface by intervening on the characteristic temporal windows where primary fundamental processes take place (fast electronic and lattice interactions). Secondly, to allow self-learning algorithms to direct the processing towards a certain path by reading and analysing the feedback from an observable parameter of the on-going experiment. 
Our first experiments [1] are based on Laser-Induced Forward Transfer of metallic thin films. We have used metals with varying electron-lattice coupling strength in order to investigate the influence of this property on this particular ablation-based processing method and furthermore in order to test the possibility to control the morphological properties of the transferred thin films. As a first step towards full pulse shaping we have employed trains of double pulses with a pulse separations ranging from 0 to 10 ps. The results show a dependence of the size and the morphology of the transferred films as the pulse separation spans time windows that are characteristic of fast electron-electron and electron-lattice interaction processes.
Current experiments involve examination of similar processes on LIFT on metal-oxides [2] where the material structure has significant qualitative differences (wide band gap) and the carrier dynamics and the primary interactions are different than in metals. In these experiments we have been able to control the size of the LIFTed films by as much as 50% by varying the temporal distance between the twin pulses that compose the shaped fs laser pulse (double pulse sequence). Also, the investigations are extended to surface processing of metallic and semiconductor surfaces [3]. Thereby, the effect of the temporal shape of the energy deposition on the morphology of the processed surface is under investigation.



Publications

  • Laser Induced Forward Transfer of metal oxides using femtosecond double pulses
    E.L. Papadopoulou, E. Axente, E. Magoulakis, C. Fotakis, P.A. Loukakos, Applied Surface Science, 257, 508, 2010

  • Laser Induced Forward Transfer of metals by temporally shaped femtosecond laser pulses
    A. Klini, P.A. Loukakos, D. Gray, A. Manousaki and C. Fotakis, Optics Express, 16, 11300, 2008

Project Members
Dr. Panagiotis Loukakos
Prof. Costas Fotakis
Dr. David Gray
Dr. Argyri Klini



Last Updated:  5/3/2013
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