Lecture Series Archive

Abstract - This talk presents novel approaches to realize nonreciprocal microwave and photonic devices without reliance on magneto-optic effects. First, I will discuss the possibilities enabled by timemodulation to implement a wide variety of low-loss nonreciprocal microwave components exhibiting fascinating functionalities, including (i) phased-array antennas that independently control their transmission/reception radiation patterns at the same operation frequency; (ii) gradient metasurfaces able to arbitrarily manipulate beams propagating in freespace; and (iii) bandpass filters and planar antennas. Then, I will describe new exciting opportunities offered by graphene and 2D materials to break and tame time-reversal symmetry at terahertz and infrared frequencies. In particular, I will focus on the spatio-temporal modulation of graphene’s conductivity to realize plasmonic isolators and how drift-currents can be exploited to construct ultrathin metasurfaces supporting plasmons completely immune to backscattering. I will finalize by discussing challenges and opportunities in the nascent field of magnetless nonreciprocity.

Dr. Sebastian Gomez-Diaz is an Assistant Professor in the Electrical and Computer Engineering Department of UC Davis, CA. He received his Ph.D. degree in EE (with honors) from the Technical University of Cartagena (UPCT, Spain) in 2011. From October 2011 to March 2014 he was a postdoctoral fellow at the École Polytechnique Fédéral de Lausanne (EPFL, Switzerland). Then, from May 2014 to August 2016, he continued his postdoctoral work in the Metamaterials and Plasmonic Research Laboratory of the University of Texas at Austin, TX. He has received several recognitions, including the NSF CAREER Award in 2018 and the Leopold Felsen Award for Excellence in Electrodynamics in 2017. His main research interests include multidisciplinary areas of electromagnetic wave propagation and radiation, metamaterials and metasurfaces, plasmonics, 2D materials, non-linear and nonreciprocal phenomena, and other emerging topics on applied electromagnetics and nanotechnology.

Abstract - The Advanced Light Source at Lawrence Berkeley National Laboratory: Beamline Science, Design, and Control The Advanced Light Source (ALS) is a national user facility designed to produce extremely bright X-Ray beams. Currently, there are over forty X-ray beamlines available at the ALS, all operating simultaneously but designed for different types of experiments in a wide range of fields, from discovery of new superconductors to characterizing protein structure. Chemists, physicists, and biologists from around the world apply for time at the ALS, and conduct experiments either onsite or remotely. The design and control of these beamlines requires a team of engineers and scientists, and typically is achieved through LabView and EPICS interfaces to motors, mirrors, and other specialized hardware. In this talk, I will cover the range of experiments conducted at the ALS, the types of software and hardware control used, and the exciting science that is enabled by the facility.

Dr. Corie Ralston has a bachelors in Physics and a doctorate in Biophysics. She completed a post-doctorate at Brookhaven National Laboratory in synchrotron techniques to study RNA structure, and is now at Lawrence Berkeley National Laboratory, where she started as a beamline scientist in 2002. Since 2012 she has been head of the Berkeley Center for Structural Biology, which runs five macromolecular crystallography X-Ray beamlines, and develops new synchrotron techniques at the Advanced Light Source.