International audienceHydrodynamics simulations and irradiation experiments were performed to correlate ultrashort intensity envelopes of the laser fields and thermodynamical states reached by the emerging plasma phase in ablation regimes. We discuss the efficiency of energy coupling as a function of different intensity envelopes and the resulting temperature, density and ionization states since the energy delivery rate is an essential factor that predetermines the material thermodynamic evolution. Subsequently, we examine the plasma composition in calculating the proportion of neutral/ion species typical of LIBS signals and comparing it with neutral/ion ratios given by experimental results. Moreover, the calculations allow to investigate the efficiency of nanoparticles generation from materials subjected to different heating rates. These can be related to hydrodynamic ejection of nanosized liquid layers upon the action of mechanic waves. With support from numerical simulations of the hydrodynamic advance of the excited matter, experiments revealed that mastering intensity envelopes of ultrashort laser pulse leads to further control on the ablation products. Emerging plasma phase in a hot state generates specific spectral emission patterns that can serve as indicators for its controlled formation and kinetic evolution

An overview of the vast array of the laser material processing techniques is presented as they apply to fabricating structures in the micro and nanometer scale length domains. The overview covers developments from the past 20 years, and encompasses demonstrated processes where the use of the inherent properties of lasers has led to increased fidelity in the processing of materials. These demonstrated processes often use inventive approaches that rely on derivative aspects of established primary principals that govern laser/material interaction phenomena. By using these nuances in concert with the unique properties of lasers, a high level of finesse has been demonstrated in materials processing. The overview highlights by the use of selective examples those processes or techniques that appear to show scalability to the industrial environment.Keywords: laser processing, overview, micro/nanofabrication, IntroductionLasers have been used in materials processing for over 50 years, though in the early days, work was more focused on mitigating laser damage in materials as opposed to the processing of materials. However, the application of lasers to controllably alter materials was recognized early and as an industry, laser processing applications now lead world wide laser sales. The calendar 2005 totals for laser process tooling is near $6.0B USD 1 . Consequently, laser materials processing can no longer be considered a niche industry as there appears to be an increasing demand to apply laser processing solutions to manufacturing for specific value added segments. Commensurate with these industry trends is the fact that the number of conferences devoted to laser material processing continues to grow. This is a normative signal that industry is currently more amenable to applying laser based solutions into the manufacturing process. There are many factors that have contributed to this change in view over the course of the past 2 decades, the primary one being the advance of laser technology with a commensurate increase in system reliability. Figure 1 shows a graph that depicts the number of world wide publications per year that mention laser material processing in the title or the abstract. The data spans nearly 40 years. The results represent a lower value to the total number of publications because there could be publications that discuss laser material processing research or development but fail to mention it in the title or abstract. The data is from an assembled series of databases that includes not only journal articles but also government sponsored research articles from the USA, Japan (e.g. MITI), Germany (e.g. BMFT), France (e.g. CNRS), Canada (e.g. NRC), UK (e.g. Department of Industry) and others. This data supports the conclusion that laser material processing is an established field that could support nearly 400 publications per year.In this paper we explore a small segment of the overall laser material processing industry, namely the use and application of lasers in micro and nanofabrication. By their ver...

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