Control of Material Transport Through Pulse Shape Manipulation-A Development Toward Designer Pulses

• Published in: IEEE journal of selected topics in quantum electronics 2014-09, Vol.20 (5), p.51-63
• Main Authors: Pangovski, Krste, Sparkes, Martin, Cockburn, Andrew, O'Neill, William, Peh Siong Teh, Dejiao Lin, Richardson, David
• Format: Article
• Language: English
• Subjects: Envelopes; Heating; Holographic interferometry; holographic recording; Holography; Imaging; Laser ablation; Laser beams; laser materials-processing applications; Lasers; Materials; Materials selection; Mathematical models; Optical surface waves; Pulse shape; pulsed lasers; silicon; Silicon substrates; Surface treatment; Temporal logic; Transport
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2014.2302441

The variety of laser systems available to industrial laser users is growing and the choice of the correct laser for a material target application is often based on an empirical assessment. Industrial master oscillator power amplifier systems with tuneable temporal pulse shapes have now entered the market, providing enormous pulse parameter flexibility in an already crowded parameter space. In this paper, an approach is developed to design interaction parameters based on observations of material responses. Energy and material transport mechanisms are studied using pulsed digital holography, post process analysis techniques and finite-difference modelling to understand the key response mechanisms for a variety of temporal pulse envelopes incident on a silicon 〈1|1|1〉 substrate. The temporal envelope is shown to be the primary control parameter of the source term that determines the subsequent material response and the resulting surface morphology. A double peak energy-bridged temporal pulse shape designed through direct application of holographic imaging data is shown to substantially improve surface quality.