Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Physics Department and Solid State Institute, Technion, Haifa 32000, Israel.
Nat Commun. 2016 Jun 13;7:ncomms11880. doi: 10.1038/ncomms11880.
Graphene plasmons have been found to be an exciting plasmonic platform, thanks to their high field confinement and low phase velocity, motivating contemporary research to revisit established concepts in light-matter interaction. In a conceptual breakthrough over 80 years old, Čerenkov showed how charged particles emit shockwaves of light when moving faster than the phase velocity of light in a medium. To modern eyes, the Čerenkov effect offers a direct and ultrafast energy conversion scheme from charge particles to photons. The requirement for relativistic particles, however, makes Čerenkov emission inaccessible to most nanoscale electronic and photonic devices. Here we show that graphene plasmons provide the means to overcome this limitation through their low phase velocity and high field confinement. The interaction between the charge carriers flowing inside graphene and the plasmons enables a highly efficient two-dimensional Čerenkov emission, giving a versatile, tunable and ultrafast conversion mechanism from electrical signal to plasmonic excitation.
石墨烯等离激元由于其具有高场限制和低相速度的特点，被认为是一种令人兴奋的等离激元平台，这激发了当代研究人员重新审视光物质相互作用中的既定概念。Čerenkov 早在 80 多年前就取得了一项概念上的突破，他展示了当带电粒子在介质中的运动速度超过光速时，如何发出光的冲击波。在现代人看来，Čerenkov 效应提供了一种从带电粒子到光子的直接、超快的能量转换方案。然而，相对论性粒子的要求使得大多数纳米级电子和光子器件都无法实现Čerenkov 辐射。在这里，我们表明，通过低相速度和高场限制，石墨烯等离激元提供了克服这一限制的手段。在石墨烯内部流动的载流子与等离激元之间的相互作用，实现了高效的二维Čerenkov 辐射，为电信号到等离激元激发提供了一种通用、可调谐且超快的转换机制。
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