Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart, 70569, Germany.
Center for Nanophotonics, AMOLF, Science Park 104, Amsterdam, 1098 XG, The Netherlands.
Nat Commun. 2019 Feb 5;10(1):599. doi: 10.1038/s41467-019-08488-4.
Relativistic electron beams create optical radiation when interacting with tailored nanostructures. This phenomenon has been so far used to design grating-based and holographic electron-driven photon sources. It has been proposed recently that such sources can be used for hybrid electron- and light-based spectroscopy techniques. However, this demands the design of a thin-film source suitable for electron-microscopy applications. Here, we present a mesoscopic structure composed of an array of nanoscale holes in a gold film which is designed using transformation optics and delivers ultrashort chirped electromagnetic wave packets upon 30-200 keV electron irradiation. The femtosecond photon bunches result from coherent scattering of surface plasmon polaritons with hyperbolic dispersion. They decay by radiation in a broad spectral band which is focused into a 1.5 micrometer beam waist. The focusing ability and broadband nature of this photon source will initiate applications in ultrafast spectral interferometry techniques.
相对论电子束与定制化的纳米结构相互作用时会产生光辐射。这一现象目前已被用于设计基于光栅和全息的电子驱动光子源。最近有人提出，这种光源可用于混合电子和基于光的光谱技术。然而，这需要设计一种适用于电子显微镜应用的薄膜光源。在这里，我们提出了一种由金膜中的纳米级孔阵列组成的介观结构，该结构采用变换光学设计，在 30-200keV 电子辐照下可产生超短啁啾电磁波包。飞秒光脉冲源于具有双曲色散的表面等离激元的相干散射。它们通过在宽光谱带中辐射而衰减，该光谱带被聚焦到 1.5 微米的束腰中。这种光子源的聚焦能力和宽带特性将引发超快光谱干涉技术的应用。
