Colloquium: Howard Milchberg

    Thursday, November 17, 2016 - 3:30pm - 5:00pm
    Meinel 307

    Spatio-temporal Optical Vortices


    When an optical pulse propagating through a nonlinear medium exceeds a certain threshold power, it can focus itself and collapse, in theory, to a singularity. In practice, several physical mechanisms mitigate or arrest the catastrophic collapse and the pulse continues propagation as a filamentary structure. This scenario has played out in many nonlinear optics systems over decades: among them are air filamentation, relativistic self-focusing in plasmas, laser-material processing, and nonlinear generation of broadband light. Recently, we showed that self-focusing collapse and collapse arrest is universally accompanied by the generation of robust topological structures: spatio-temporal optical vortices (STOVs).  In contrast to the conventional orbital angular momentum vortices in Laguerre-Gaussian beams, STOVs have electromagnetic phase circulation in a spatio-temporal plane that propagates with the pulse and directs the global pulse energy flow.  I will describe our experiments, simulations and calculations leading to our discovery of STOVs , and discuss future possible applications.

    Speaker Bio(s): 

    Howard Milchberg received his undergraduate degree in Engineering Physics from McMaster University. He held a National Science and Engineering Research Council of Canada Fellowship at Princeton University, where he completed his Ph.D. in Astrophysical Sciences in 1985. His dissertation was on one of the first two soft x-ray lasers experimentally demonstrated. Milchberg then joined AT&T Bell Laboratories as a postdoc, where he performed among the first experiments in high intensity femtosecond laser-plasma interactions. In 1988 Milchberg joined the University of Maryland, where he received a NSF Presidential Young Investigator Award. He is a Professor in Departments of Physics and Electrical and Computer Engineering. Milchberg is a Distinguished Scholar-Teacher at Maryland and a recipient of the Senior Faculty Outstanding Research Award from the Clark School of Engineering. He is a Fellow of the APS and the OSA. In 2005, he was awarded the APS Division of Plasma Physics (DPP) Award for Excellence in Plasma Physics Research. Three of his graduate students, most recently in 2012, have won the APS-DPP Marshall Rosenbluth Award for their dissertation research.