Femtosecond laser surface processing (FLSP) involves the interaction of ultra-short laser pulses with metallic surfaces, and when rastered under the focused laser beam, produces self-organized surfaces often imitating the micro/nanoscale surfaces features found in nature. The fundamentals of the formation of self-organized structures at the micron and nanoscale will be discussed. The self-organized structures highly depend on the laser fluence and the shot number associated with the raster scanning process. The surface features alter the wetting properties of the surface and can result in either super-hydrophilic or superhydrophobic surfaces. Superhydrophilic metallic surfaces can result in metallic surfaces that are super-wicking. Results will be presented where these surfaces are used to enhance the heat transfer in pool boiling experiments and reduce the drag in annual fluid flows. Experiments will be discussed on the functionalization of Cu and the formation of new phases of Cu. Results indicate that at the ultra-short laser pulses can change the phase of Cu from the normal face center cubic structure to body center cubic structure. Results of the modeling work comparing experimental work and theoretical calculations will be presented on the formation of laser induced periodic structures formed at low fluence values.
Dennis R. Alexander received the Ph.D. degree in Nuclear Engineering/Physics from Kansas State University. He joined the faculty at University of Nebraska as an Assistant Professor of Mechanical Engineering in 1975 where he taught mechanical engineering courses as well as nuclear engineering courses. He worked at Los Alamos Scientific Laboratory and AMOCO research center. He was promoted to full professor of mechanical engineering and received a Kingery Chaired Professorship. He founded the Center for Electro-Optics and Functionalized Surfaces (CEFS) and is currently the director. He joined the Electrical Engineering and Computer Engineering Department in 1993 and has spent the last 21 years in this department developing the ultra-fast femtosecond laser interaction with matter research program at the University of Nebraska. His research interests span over a broad range of areas, including electromagnetics, femtosecond pump-probe measurement of electron dynamics, laser induced breakdown spectroscopy, and the light matter interactions at extreme intensities where the relativistic magnetic force term becomes important. He has been the author or the co-author of 200 journal papers, 225 conference papers, 2 book chapters and 12 patents. He has received numerous teaching awards during his career.