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The past decade has witnessed a surge of interest in the theory and application of time-varying components in engineered photonic and electromagnetic structures. While time-varying photonic materials have been shown to enable novel and unique physical phenomena, many of these research efforts have been additionally motivated by the desire to overcome various performance limits related to, for instance, antenna radiation, absorption, and impedance matching. Given that many physical limits in electromagnetism/photonics are typically derived under the assumption of passivity and time-invariance, judicious time-varying designs may challenge and overcome these limitations. In this context, the most common design strategy involves employing a time-switched material, where one or more of the constitutive parameters undergo abrupt changes in time. Although this approach offers promising results, its implementation poses significant challenges. Specifically, complex synchronization mechanisms are necessary to accurately time the switching of the material parameters with respect to the arrival time of the pulse. Additionally, the switching event usually needs to take place when the pulse is entirely contained within the medium, leading to a potential constraint on the minimum thickness of the time-varying system. Here, we show that, instead of a time-switched material, certain periodically modulated time-Floquet systems can significantly enhance the absorption bandwidth and can even go beyond the conventional bounds of a thin absorber without prior knowledge of the arrival time of the pulse. Our findings may open a new route in the design of time-varying systems that are not bound by conventional performance limits and may facilitate their implementations.
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