Spatial and temporal laser pulse design for material processing on ultrafast scales

Abstract

International audienceThe spatio-temporal design of ultrafast laser excitation can have a determinant influence on the physical and engineering aspects of laser-matter interactions,with the potential of upgrading laser processing effects. Energy relaxation channels can be synergetically stimulated as the energy delivery rate is synchronized with the material response on ps timescales. Experimental and theoretical loops based on the temporal design of laser irradiation and rapid monitoring of irradiation effects are, therefore, able to predict and determine ideal optimal laser pulse forms for specific ablation objectives.We illustrate this with examples on manipulating the thermodynamic relaxation pathways impacting the ablation products and nanostructuring of bulk and surfaces using longer pulse envelopes. Some of the potential control factors will be pointed out. At the same time the spatial character can dramatically influence the development of laser interaction. We discuss spatial beam engineering examples such as parallel and non-diffractive approaches designed for highthroughput, high-accuracy processing events

Fs‐Laser Processing of Glass: Plasma Dynamics and Spectroscopy

“…In this sense, special attention has been paid on the investigation of the dynamics of laser‐generated plasmas in glass using different kinds of experimental layouts at the surface and in bulk, as well as theoretical models based on simple and multiple rate equations. Recently, the manipulation of the temporal and spatial laser shape (pulse shaping techniques) has been exploited for enhancing the laser energy coupling in glasses with the goal of optimizing the final optical, topographical, morphological, or structural modification …”

Effects of aberrations in spatiotemporal focusing of ultrashort laser pulses

“…There are extensive subsequent investigations using SSTF in imaging, such as adjusting group velocity dispersion for refocusing [7], imaging of biological samples [8], the creation of novel excitation patterns for biological photoactivation [9,10], as well as theoretical treatment [11]. Concurrently SSTF has also been implemented in laser fabrication, where demonstrations include the generation of hollow microfluidic channels [12], control of the pulse front tilt (PFT) for directional laser writing [13,14], 3D lithographic microfabrication [15], patterned excitation [16], and longer pulse envelope fabrication [17].…”

Control of Ultrafast Laser Nanostructuring of Glasses using Temporal and Spatial Pulse Design

“…Different relaxation times are observed for the various photoinscription regimes, witnessing specific electronic relaxation paths ranging from rapid defect trapping in type I to slower decay triggering thermomechanical transitions in type II domains. As the type II nanoscale spontaneous arrangement is intermediated by electronic excitation, we equally propose a method of real time control and optimization of nanogratings formation in bulk fused silica under the action of ultrashort laser pulse with programmable variable envelopes [3,6]. Varying the pulse temporal envelope, a certain tunability of nanogratings period can be achieved ( Fig.…”