Tunable narrowband terahertz emission from mastered laser-electron beam interaction
Tunable narrowband terahertz emission from mastered laser-electron beam interaction
复制标题
DOI：
10.1038/nphys916
复制
发表时间：
2008-05-01
期刊：
影响因子：
19.6
通讯作者：
Takashima, Y.
中科院分区：
文献类型：
--
作者：
Bielawski, S.;Evain, C.;Takashima, Y.
在寻找太赫兹域的光辐射源方面，有希望的候选是当强激光与材料介质(1-5)相互作用时发生的非线性光学过程。除了传统的介质(如晶体)，相对论电子还表现出惊人的非线性集体行为，这可以导致强大的激光诱导相干发射(6，7)，揭示了这些器件作为太赫兹源的巨大潜力(8)。然而，到目前为止，只报告了宽带发射，对它们的辐射特性，如光谱(9，10)的实验控制仍然是一个重要的挑战。在这里，我们论证了通过产生可调谐的窄带太赫兹辐射来实验控制相干辐射的可能性。电子束与具有纵向准正弦调制的激光脉冲发生相互作用，窄带发射发生在准均匀磁场区域。因此，这一过程与经典的同步辐射实验有很大的不同，在传统的同步辐射实验中，窄带发射发生在周期性磁场中。
In the quest for sources of optical radiation in the terahertz domain, promising candidates are nonlinear optical processes occurring when an intense laser beam interacts with a material medium(1-5). Besides conventional media (such as crystals), relativistic electrons also show striking nonlinear collective behaviours, which can lead to powerful laser-induced coherent emission(6,7), revealing huge potentials of these devices as terahertz sources(8). However, up to now only broadband emissions were reported, and experimental control of their radiation properties, such as their spectra(9,10), remained an important challenge. Here, we demonstrate the possibility of mastering the coherent emission experimentally by producing tunable narrowband terahertz radiation. The interaction is made to occur between an electron beam and laser pulses possessing a longitudinal quasi-sinusoidal modulation, and the narrowband emission occurs in a region of quasi-uniform magnetic field. The process therefore strongly differs from classical synchrotron radiation experiments, where narrowband emission occurs inside a periodic magnetic field.