门控石墨烯等离子体激元的光学纳米成像
Optical nano-imaging of gate-tuneable graphene plasmons
摘要：
操纵光场和光的能量流的能力是现代信息和通信技术以及量子信息处理方案的核心。然而，由于光子不带电荷，因此迄今为止，通过电学手段有效地控制它们是难以实现的。实现光的电控制的一种有希望的方法可能是通过石墨烯中的等离子体激元-光子和载流子的耦合激发。在这种二维碳原子片中，预期等离子体激元及其相关的光场可以通过改变石墨烯载流子密度而容易地进行电调谐。虽然光学石墨烯等离子体共振最近已经被光谱学研究，但到目前为止还没有实验直接解决了真实空间中的传播等离子体。在这里，我们发射和检测传播光学等离子体在锥形石墨烯纳米结构，使用近场散射显微镜与红外激发光。我们提供了等离子体场分布的真实空间图像，并发现提取的等离子体波长非常短-比照明波长小40倍以上。我们利用这种强大的光场限制，将石墨烯纳米结构转变为具有极小模体积的可调谐共振等离子体腔。腔共振通过门控石墨烯原位控制，并且特别地，证明了等离子体激元模式的完全打开和关闭，从而为基于石墨烯的光学晶体管铺平了道路。纳米电子学和纳米光学之间的这种成功联盟使得能够开发前所未有的有源亚波长尺度光学器件和大量新颖的纳米光电子器件和功能，例如可调超材料、纳米级光学处理和用于量子器件和（生物）传感器的强烈增强的光-物质相互作用。
英文摘要：
The ability to manipulate optical fields and the energy flow of light is central to modern information and communication technologies, as well as quantum information processing schemes. However, as photons do not possess charge, controlling them efficiently by electrical means has so far proved elusive. A promising way to achieve electric control of light could be through plasmon polaritons - coupled excitations of photons and charge carriers - in graphene. In this two-dimensional sheet of carbon atoms, it is expected that plasmon polaritons and their associated optical fields can be readily tuned electrically by varying the graphene carrier density. While optical graphene plasmon resonances have recently been investigated spectroscopically, no experiments so far have directly resolved propagating plasmons in real space. Here, we launch and detect propagating optical plasmons in tapered graphene nanostructures using near-field scattering microscopy with infrared excitation light. We provide real-space images of plasmonic field profiles and find that the extracted plasmon wavelength is remarkably short - over 40 times smaller than the wavelength of illumination. We exploit this strong optical field confinement to turn a graphene nanostructure into a tunable resonant plasmonic cavity with extremely small mode volume. The cavity resonance is controlled in-situ by gating the graphene, and in particular, complete switching on and off of the plasmon modes is demonstrated, thus paving the way towards graphene-based optical transistors. This successful alliance between nanoelectronics and nano-optics enables the development of unprecedented active subwavelength-scale optics and a plethora of novel nano-optoelectronic devices and functionalities, such as tunable metamaterials, nanoscale optical processing and strongly enhanced light-matter interactions for quantum devices and (bio)sensors.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
