Title: Breaking Lorentz Reciprocity: From Physics to New Wireless Communication Paradigms
Negar Reiskarimian
Abstract: Lorentz reciprocity is a fundamental characteristic of the vast majority of electronic and photonic structures. However, breaking reciprocity enables the realization of non-reciprocal components, such as isolators and circulators, which are critical to electronic and optical communication systems, as well as new components and functionalities based on novel wave propagation modes. In this talk, I will present a novel approach to break Lorentz reciprocity based on linear periodically-time-varying (LPTV) circuits. We have demonstrated the world's first CMOS passive magnetic-free non-reciprocal circulator through spatio-temporal conductivity modulation. Since conductivity in semiconductors can be modulated over a much wider range than the more traditionally exploited permittivity, our structure is able to break reciprocity within a compact form factor with very low loss and high linearity. I will further discuss some of the fundamental limits of space-time modulated nonreciprocal structures, as well as new directions to build non-reciprocal components which can ideally be infinitesimal in size.
One of the emerging applications of non-reciprocity is within the next generation of wireless communication networks or “5G”. Enabling these technologies requires a re-evaluation and redesign of various layers of the communication system, from the PHY layer all the way up to the application layer. In the case of the PHY layer, conventional reciprocal antenna interfaces impose fundamental limitations on the radio front-end design. Here, I will present our recent efforts on designing full-duplex systems using integrated antenna interfaces to address these challenges.
Looking to the future, I am broadly interested in exploring novel fundamental physical concepts that have strong engineering applications. I wish to work in an interdisciplinary area between integrated circuit design and closely related fields such as applied physics, applied electromagnetics and nanophotonics, and to identify and investigate ideas and concepts that can best be implemented using the semiconductor platform. Finally, I will share with you some examples of the exciting research directions I would like to pursue with the aim of participating in building the next generation of technologies that augment human lives.
Bio: Negar Reiskarimian received the Bachelor’s and Master’s degrees in electrical engineering from Sharif University of Technology in Iran, and is currently a PhD candidate in Electrical Engineering at Columbia University. Her research broadly focuses on integrated circuits and systems and applied electromagnetics, with a current emphasis on novel non-reciprocal components for emerging wireless communication paradigms. She has published in top-tier IEEE IC-related journals and conferences, as well as broader-interest high-impact journals in the Nature family. Her research has been widely covered in the press, and featured in IEEE Spectrum, Gizmodo and EE Times among others. She is the recipient of numerous awards and fellowships, including Forbes “30 under 30”, Paul Baran Young Scholar, Qualcomm Innovation Fellowship and multiple IEEE societies awards and fellowships.