Nonreciprocal manipulation of electromagnetic waves

Dr. Sebastian Gomez-Diaz
Assistant Professor ECE Department, UC Davis, Davis, CA

Cerent Engineering Science Complex, Salazar Hall 2009A
4:00 PM

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.