Using Time-Varying Systems to Challenge Fundamental Limitations in Electromagnetics

Abstract

Time-varying components provide an exceptional opportunity to explore novel means for building efficient electromagnetic devices. While such explorations date back to more than half a century ago, recent years have experienced a renewed and increased interest into the design of dynamic electromagnetic systems. This resurgence has been partly fueled by the desire to surpass the performance of conventional devices, and to enable systems that can challenge various well-established physical bounds, such as the Bode-Fano limit, the Chu limit, etc. Here, we overview this emerging research area and provide a concise and systematic summary of the most relevant applications for which the relevant physical bounds can be overcome through time-varying elements. Besides leading to devices with superior performances, such research endeavors open new possibilities and might offer insight towards future all-electromagnetic/optical technologies.

Metasurface-Based Realization of Photonic Time Crystals

“…Time, as an additional degree of freedom, has significantly extended the potential of artificial electromagnetic materials [1][2][3]. In the past few years, numerous new physical effects have been discovered based on time modulation of material properties, such as magnetless nonreciprocity [4,5], effective magnetic field for photons [6,7], synthetic dimensions [8][9][10][11], electromagnetic devices beyond physical bounds [12,13], among many others [1]. One of the major developments in this direction is the concept of photonic time crystals (PhTCs) [14,15].…”