Physics Journal Club Meeting Butterfly effect in high-power, ultrashort laser propagation Rostislav Grynko Department of Physics, Applied Physics and Astronomy, Binghamton University Modern pulsed-laser systems have dramatically reshaped our understanding of light and how it interacts with matter. Commercially available Ti:Sapphire laser pulses with durations of a few femtoseconds (10 -15 s) routinely deliver peak powers on the order of gigawatts and even higher. During propagation, a high power beam will exhibit highly-nonlinear behavior: without the aid of a lens, it will self-focus until it reaches an intensity for which any material can be ionized along its path, including air, giving rise to a column of plasma. This highintensity, self-guiding light structure is known as a filament, and it serves as an indispensable tool in many applications, among which include lightning control, new light sources, and laser-based weapon technology. In this presentation I will outline the physics of powerful laser beams in the context of filament formation. In particular, I will discuss a process known as multi-filamentation, whereby a laser beam breaks up into many parts. The phenomenon is highly stochastic, akin to the butterfly effect. Since their formation is unpredictable, multiple filaments pose a series of problems to laser-based technology, so it is highly desirable to develop a means by which the process can be controlled. In our experiments, we show that control and even complete elimination of multi-filamentation can be achieved under proper focusing conditions. We develop a highly versatile method to control beam breakup, and support our findings with a series of numerical simulations. The high degree of control over nonlinearities that our results provide is supplemented with a series of surprising physical insights which may be applicable to processes as seemingly unrelated as ocean waves. Gaussian beam Stochastic multiple filament formation Friday, September 25, 2015 S2 Bldg. Room 138 Pizza @ Noon Presentation @ 12:15 There will be a sign-in sheet for all attendees to sign.