Demonstration of coherent terahertz transition radiation from relativistic laser-solid interactions

Liao, Guo-Qian and Li, Yu-Tong and Zhang, Yi-Hang and Liu, Hao and Ge, Xu-Lei and Yang, Su and Wei, Wen-Qing and Yuan, Xiao-Hui and Deng, Yan-Qing and Zhu, Bao-Jun and Zhang, Zhe and Wang, Wei-Min and Sheng, Zheng-Ming and Chen, Li-Ming and Lu, Xin and Ma, Jing-Long and Wang, Xuan and Zhang, Jie (2016) Demonstration of coherent terahertz transition radiation from relativistic laser-solid interactions. Physical Review Letters, 116. 205003. ISSN 1079-7114 (https://doi.org/10.1103/PhysRevLett.116.205003)

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Abstract

Coherent transition radiation in the terahertz (THz) region with energies of sub-mJ/pulse has been demonstrated by relativistic laser-driven electron beams crossing the solid-vacuum boundary. Targets including mass-limited foils and layered metal-plastic targets are used to verify the radiation mechanism and characterize the radiation properties. Observations of THz emissions as a function of target parameters agree well with the formation-zone and diffraction model of transition radiation. Particle-in-cell simulations also well reproduce the observed characteristics of THz emissions. The present THz transition radiation enables not only a potential tabletop brilliant THz source, but also a novel noninvasive diagnostic for fast electron generation and transport in laser-plasma interactions.