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Time-Varying Non-Hermitian Metamaterials: Probing and Challenging the Fundamental Limits of Electromagnetics and Photonics

ECE Seminar

Location: EER 1.518
Zeki Hayran
Department of Electrical and Computer Engineering at Cornell University

Time-varying systems present unique opportunities for developing advanced electromagnetic and photonic devices. While research in this area originated more than fifty years ago, it is only in recent years that there has been a significant surge of research interest and momentum towards developing time-varying electromagnetic systems for various applications. This resurgence is driven partly by the realization that such systems may outperform traditional devices and overcome established performance limitations, such as the Bode–Fano limit for impedance matching, the Rozanov limit for electromagnetic absorption, the Chu-Harrington limit for small antennas, the delay-bandwidth limit, and various constraints due to reciprocity. In this talk, I will discuss our recent research efforts exploring both the potential and limitations of this emerging field. I will show how time-varying systems, combined with concepts from metamaterials and non-Hermitian physics, can unveil unique phenomena and achieve unique capabilities surpassing those of time-invariant systems. Furthermore, I will show how the unique properties of the temporal dimension, particularly in terms of causality and energy conservation, introduce distinct challenges and physical limitations specific to time-varying systems, despite the often-invoked space-time duality in wave physics.


Zeki Hayran is currently a PhD candidate in the Department of Electrical and Computer Engineering at Cornell University, supervised by Assoc. Prof. Francesco Monticone. His research focuses on metamaterials, time-varying photonics, and non-Hermitian optics. He is the recipient of multiple awards, including the Fulbright FellowshipIEEE Photonics Society Graduate Student FellowshipSPIE Optics and Photonics Fellowship, and the Milton Chang Travel Award. Hayran has authored over 18 papers published in peer-reviewed journals including OpticaACS Photonics, and Nature Communications. He has also contributed to over 25 conference proceedings and delivered over 20 conference presentations, three of which were invited talks.