Tunable Cherenkov radiation based on a van der Waals semiconductor α-MoO₃ and graphene hybrid

In this Letter, we explore the Cherenkov radiation properties of α-phase molybdenum trioxide (α-MoO₃). We demonstrate that the asymmetric, forward, and reverse Cherenkov radiation can simultaneously exist by rotating the α-MoO₃ slab at the same working frequency and structure. In addition, thanks to the tunable functionalities of graphene, the conversion of forward and reverse Cherenkov radiation can be actualized by altering the Fermi level of graphene. These dynamically adjustable features provide a novel, to the best of our knowledge, and intuitive way for tunable Cherenkov radiation in the mid-infrared range, which opens up new opportunities in designing and manufacturing tunable radiation sources in future.