Physics Department, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
Max Planck Institute for the Science of Light, Erlangen, Germany.
Nature. 2021 Sep;597(7877):498-502. doi: 10.1038/s41586-021-03812-9. Epub 2021 Sep 22.
Particle accelerators are essential tools in science, hospitals and industry. Yet their costs and large footprint, ranging in length from metres to several kilometres, limit their use. The recently demonstrated nanophotonics-based acceleration of charged particles can reduce the cost and size of these accelerators by orders of magnitude. In this approach, a carefully designed nanostructure transfers energy from laser light to the particles in a phase-synchronous manner, accelerating them. To accelerate particles to the megaelectronvolt range and beyond, with minimal particle loss, the particle beam needs to be confined over extended distances, but the necessary control of the electron beam's phase space has been elusive. Here we demonstrate complex electron phase-space control at optical frequencies in the 225-nanometre narrow channel of a silicon-based photonic nanostructure that is 77.7 micrometres long. In particular, we experimentally show alternating phase focusing, a particle propagation scheme for minimal-loss transport that could, in principle, be arbitrarily long. We expect this work to enable megaelectronvolt electron-beam generation on a photonic chip, with potential for applications in radiotherapy and compact light sources, and other forms of electron phase-space control resulting in narrow energy or zeptosecond-bunched beams.
粒子加速器是科学、医院和工业中不可或缺的工具。然而，它们的成本和庞大的占地面积（长度从几米到几公里不等）限制了它们的使用。最近基于纳米光子学的带电粒子加速技术可以将这些加速器的成本和尺寸降低几个数量级。在这种方法中，经过精心设计的纳米结构以相位同步的方式将能量从激光传输到粒子上，从而加速它们。为了将粒子加速到兆电子伏特范围及以上，同时最大限度地减少粒子损失，粒子束需要在长距离上被限制，但电子束的相位空间的必要控制一直难以实现。在这里，我们在一个基于硅的光子纳米结构的 225 纳米窄通道中演示了光学频率下的复杂电子相位空间控制，该结构长 77.7 微米。特别是，我们实验展示了相位交替聚焦，这是一种用于最小损耗传输的粒子传播方案，原则上可以任意长。我们预计这项工作将能够在光子芯片上产生兆电子伏特的电子束，有望应用于放射治疗和紧凑型光源，以及其他形式的电子相位空间控制，从而产生窄能或zeptosecond 级别的聚束束。
