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Polarization Shaping of Free‐Electron Radiation by Gradient Bianisotropic Metasurfaces
Author(s) -
Jing Liqiao,
Lin Xiao,
Wang Zuojia,
Kaminer Ido,
Hu Hao,
Li Erping,
Liu Yongmin,
Chen Min,
Zhang Baile,
Chen Hongsheng
Publication year - 2021
Publication title -
laser and photonics reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.778
H-Index - 116
eISSN - 1863-8899
pISSN - 1863-8880
DOI - 10.1002/lpor.202000426
Subject(s) - physics , radiation , microwave , electron , polarization (electrochemistry) , optics , free electron model , electromagnetic radiation , laser , chemistry , quantum mechanics
Abstract Free‐electron radiation phenomena facilitate enticing potential to create light emission with highly tunable spectra, covering hard‐to‐reach frequencies ranging from microwave to X‐ray. Consequently, they take part in many applications such as on‐chip light sources, particle accelerators, and medical imaging. While their spectral tunability is extremely high, their polarizability is usually much harder to control. Such limitations are especially apparent in all free electron based spontaneous radiation sources, such as the Smith−Purcell (SP) radiation. Here, anomalous free‐electron radiation phenomenon is demonstrated at the microwave regime from gradient bianisotropic metasurfaces, by using a phased dipole array to mimics moving charged particles. The phase gradient and the bianisotropy in metasurfaces provide new degrees of freedom for the polarization shaping of free‐electron radiation, going beyond the common spectral and angular shaping. Remarkably, the observed anomalous free‐electron radiation obeys a generalized SP formula derived from Fermat's principle.