<title>Temporal pulse manipulation and adaptive optimization in ultrafast laser processing of materials</title>

Abstract

Ultrafast lasers have become reliable tools for material processing on reduced scales, with extended options for process control and optimization. The additional possibility to shape the temporal envelope of ultrashort laser pulses by Fourier synthesis of spectral components enables completely new opportunities for optimal processing of materials. The concept of optimizing laser interactions is based on the possibility to regulate the energy delivery rate and to achieve control of laser-induced phenomena. An experimental demonstration of the technique showing the possibility to design excitation sequences tailored with respect to the material response will be described, laying the groundwork for adaptive optimization in materials structuring. We present recent results related to the implementation of self-learning loops based on temporal shaping of the ultrafast laser pulses to control laser-induced phenomena for practical applications. Besides the fundamental interest, it will be shown that under particular excitation conditions involving modulated excitation, the energy flow can be controlled and the material response can be guided to improve processing results. Examples will be given illuminating the possibility to optimize the kinetic properties of ions emitted from laser-irradiated semiconductor samples, uisng excitation sequences synchronized with the phase-transformation characteristic times, unfolding also interesting perspectives for "intelligent" processing of materials.