Using Time-Varying Systems to Challenge Fundamental Limitations in Electromagnetics: Overview and summary of applications

Time-varying systems open intriguing opportunities to explore novel approaches in the design of 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 performance bounds, such as the Bode–Fano limit, the Chu limit, and others. Here, we give an overview of this emerging research area and provide a concise and systematic summary of the most relevant applications for which the relevant performance bounds can be overcome through time-varying elements. In addition to enabling devices with superior performance metrics, such research endeavors may open entirely new opportunities and offer insight towards future electromagnetic and optical technologies.