Exciton resonance tuning of an atomically thin lens
Exciton resonance tuning of an atomically thin lens
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DOI：
10.1038/s41566-020-0624-y
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发表时间：
2020-04-27
期刊：
影响因子：
35
通讯作者：
Brongersma, Mark L.
中科院分区：
文献类型：
--
作者：
van de Groep, Jorik;Song, Jung-Hwan;Brongersma, Mark L.
谐振光学天线的高度可设计的散射特性支撑着基于超表面的平面光学器件的运行。到目前为止，天线的选择仅限于支持几何等离子体或米氏共振的成形金属和高折射率半导体纳米结构。尽管这些谐振元件提供了强烈的光与物质相互作用以及对散射相位和振幅的出色控制，但它们的电可调谐性已被证明是相当有限的。在这里，我们演示了如何利用原子薄半导体中的激子共振作为不同的第三种类型的共振来创建可变的平面光学器件。这些基于材料的强共振对各种外部刺激的可调性是无与伦比的。为了说明这个概念，我们首先演示激子如何提高毫米级图案化 WS2 波带片透镜的聚焦效率。我们还展示了电门控如何完全打开和关闭激子共振，从而将聚焦效率调节33%。通过利用单层WS2在可见光谱范围内的激子共振，可以实现大面积、主动可调和原子级薄的光学透镜。
The highly engineerable scattering properties of resonant optical antennas underpin the operation of metasurface-based flat optics. Thus far, the choice of antenna has been limited to shaped metallic and high-index semiconductor nanostructures that support geometrical plasmonic or Mie resonances. Whereas these resonant elements offer strong light-matter interaction and excellent control over the scattering phase and amplitude, their electrical tunability has proven to be quite limited. Here, we demonstrate how excitonic resonances in atomically thin semiconductors can be harnessed as a different, third type of resonance to create mutable, flat optics. These strong materials-based resonances are unmatched in their tunability with various external stimuli. To illustrate the concept, we first demonstrate how excitons can enhance the focusing efficiency of a millimetre-scale, patterned WS2 zone plate lens. We also show how electrical gating can completely turn on and off the exciton resonance and thereby modulate the focusing efficiency by 33%.By harnessing the excitonic resonances of a monolayer of WS2 in the visible spectral range, large-area, actively tunable and atomically thin optical lenses can be realized.