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Wave shaping plays an important role in on‐chip signal processing. However, previously reported photonics elements exhibit limited control capabilities or require complex nanofabrication techniques. Here, an on‐chip metadevice is proposed for multiport beam splitting based on a 1D slots array on the silicon‐on‐insulator platform, which has the advantages of high efficiency, full 2π phase shift, and an easy design scheme. The proposed metadevice is experimentally demonstrated at 1550 nm, which shows different numbers of beam splits. This design provides a new solution for on‐chip beam splitting, which has great potential in wide applications such as signal processing, on‐chip laser modulation, on‐chip neural network, etc. [ABSTRACT FROM AUTHOR]

A moving charged particle, such as an electron, can radiate light due to the interaction between its Coulomb field and surrounding matter. This phenomenon has spawned great interest in the fields of physics, electron microscopy, optics, biology, and materials science. Since the radiation generated by the charged particles strongly depends on the surrounding matter, artificially engineered materials with exotic electromagnetic and optic properties, including metamaterials and metasurfaces, provide an unprecedented opportunity to tailor the interaction between the charged particle and matter, and ultimately enable to manipulate the radiated light. In this review, the fundamentals of Cherenkov radiation and Smith–Purcell radiation are presented. Subsequently, the recent advances in the control of Cherenkov radiation and Smith–Purcell radiation based on metamaterials and metasurfaces are summarized. Finally, the applications using these two physical phenomena, including electron‐driven photon sources and electron accelerators, are discussed in this review. [ABSTRACT FROM AUTHOR]