March 9, 2011 Wednesday 15:30
Selçuk Aktürk, Istanbul Technical University
Applications of Laser-induced Plasma Channels: From Terahertz to Lightning Protection

Abstract: Thanks to their extremely short durations, femtosecond laser pulses can reach unprecedented levels of peak powers and intensities. If the laser power is above a critical threshold, the beam self-focusing can overcome diffraction, resulting in beam size getting smaller by propagation. The correspondingly increasing intensity then reaches levels sufficient to ionize the propagation medium. At this point, a defocusing plasma is formed and the beam propagates in a balanced manner over a long “light filament”. Plasma channels in air formed through filamentation have several important applications. The conductivity of filament can be exploited to trigger and guide lightning, for example. By controlling the longitudinal position of the filament and analyzing the backscattered light from plasma, a LIDAR configuration can also be formed and composition in a distant target can be analyzed. Finally, the oscillations in the plasma channel also give rise to Cherenkov-type emission of secondary Terahertz radiation.

Biography: Asst.. Prof. Selçuk Aktürk received his BS degree in Physics from Bilkent University in 2001, and his PhD degree in Physics from Georgia Institute of Technology in 2005. He pursued post-doctoral studies at Swamp Optics LLC in USA and Ecole Polytecnique in France. He has been a faculty member in Istanbul technical University, Department of Physics since April 2009. He performs research in the area of Optics and Photonics, particularly in fields of ultrafast optics, laser-matter interactions, nonlinear optics and laser micromachining.