基于非弹性电子隧穿的表面等离激元激发

表面等离激元是一种存在于金属(或掺杂半导体)-介质界面的电磁极化和振荡现象,可以显著增强纳米尺度光与物质的相互作用,在波导、生化传感、超快调制、探测以及非线性光学等领域具有重要应用前景。表面等离激元的激发主要采用受衍射极限限制的光学激发方式,通常需要棱镜、光栅等大尺寸光学元件的辅助,这极大限制了等离激元器件的小型化和片上高密度集成。通过将等离激元纳米结构和隧道结集成起来,低能量的隧穿电子可以直接激发该结构的等离激元模式,具有超小尺寸、超快调制速度等优点。本文将回顾基于电子隧穿效应的表面等离激元激发的研究历史,并着重介绍该领域的最新研究进展。

Inelastic Electron Tunneling-Based Excitation of Surface Plasmons

Surface plasmons are highly confined electromagnetic modes coherently coupled to collective oscillations of free carriers at metal (or doped semiconductor) interfaces, which can greatly enhance light-matter interaction at the nanoscale and have found valuable applications in areas such as waveguiding, biochemical sensing, ultrafast modulation, detection and nonlinear optics. They are usually excited by diffraction-limited optical approaches with the use of bulky optical components (prisms, gratings,etc), which greatly limit the miniaturization of plasmonic devices and their chip-scale high-density integration. By integrating a plasmonic nanostructure with a quantum tunnel junction, low-energy inelastically tunneled electrons can directly excite plasmonic modes in the nanostructure with advantages such as ultra-small footprint and ultra-fast speed. In this paper, recent research progress in the inelastic tunneling-based electric excitation of localized and propagating surface plasmons is overviewed.