Multiscale Measurement of Electron Dynamics in High-Speed, High-Quality, High-Aspect Ratio Femtosecond Laser Drilling: Russell Severance Springer Colloquium

Seminar | January 31 | 4-5 p.m. | 3110 Etcheverry Hall

 Department of Mechanical Engineering (ME)

Abstract: By spatially/temporally shaping femtosecond laser pulses, localized transient electron dynamics can be actively controlled during ultrafast laser-material interactions. Based on this mechanism, high-quality microholes with a diameter of 1.6 μm and an aspect ratio of 1000:1 are fabricated by a shaped single femtosecond laser pulse. It takes 42 min to fabricate 251,000 holes in a 1 cm × 1 cm area. The holes are very uniform in size and shape. A multiscale measurement system (from the femtosecond scale to microsecond scale) is proposed and developed for cross-time-scale electron dynamics during femtosecond laser drilling. It consists of a pump-probe shadowgraph imaging technique, laser-induced breakdown spectroscopy (LIBS), and an intensified charge-coupled device (ICCD) camera. We reveal the multiple time-scale fundamentals during femtosecond laser material interactions, including the femtosecond-scale propagation of a laser pulse, picosecond-scale generation/evolution of laser-induced plasma, nanosecond-scale plasma ejection/expansion, and microsecond-scale hole formation.

Biography: Dr. Lan Jiang, the Changjiang Distinguished Professor at the Beijing Institute of Technology, received the Second Award of National Natural Sciences (Central Government of China), Ho Leung Ho Lee Innovation Award, the First Award of Natural Sciences (Ministry of Education of China), the First Award of Innovation (Ministry of Education of China), and National Outstanding Young-Scientist Award (National Natural Science Foundation of China). Over the past twelve years, as the Principal Investigator, he has received 25 grants totaling RMB181 million (approximately $26 million including facilities). He was elected as the National Leading Researcher for S&T Innovations and the Leader of Innovation Group of Ministry of Education of China. Dr. Jiang serves as Chief Scientist of National Basic Research Program of China, Director of National Innovation Center for High-Precision Micro-Fabrication, and Dean of the School of Mechanical Engineering at the Beijing Institute of Technology. He is an ASME Fellow, OSA Fellow, and ISNM Fellow. Dr. Jiang has authored 247 journal papers and 60 patents. He has delivered 19 plenary/keynote presentations and 50 invited talks in mainstream international conferences.

 cgrigoro@berkeley.edu, 510-642-2525