Zeng Shuwen, Liang Guozhen, Gheno Alexandre, Vedraine Sylvain, Ratier Bernard, Ho Ho-Pui, Yu Nanfang
XLIM Research Institute, UMR 7252 CNRS/University of Limoges, 123 Avenue Albert Thomas, 87060 Limoges, France.
Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA.
Nanomaterials (Basel). 2020 Jun 30;10(7):1289. doi: 10.3390/nano10071289.
In this work, we have designed highly sensitive plasmonic metasensors based on atomically thin perovskite nanomaterials with a detection limit up to 10 refractive index units (RIU) for the target sample solutions. More importantly, we have improved phase singularity detection with the Goos-Hänchen (GH) effect. The GH shift is known to be closely related to optical phase signal changes; it is much more sensitive and sharp than the phase signal in the plasmonic condition, while the experimental measurement setup is much more compact than that of the commonly used interferometer scheme to exact the phase signals. Here, we have demonstrated that plasmonic sensitivity can reach a record-high value of 1.2862 × 10 µm/RIU with the optimum configurations for the plasmonic metasensors. The phase singularity-induced GH shift is more than three orders of magnitude larger than those achievable in other metamaterial schemes, including Ag/TiO hyperbolic multilayer metamaterials (HMMs), metal-insulator-metal (MIM) multilayer waveguides with plasmon-induced transparency (PIT), and metasurface devices with a large phase gradient. GH sensitivity has been improved by more than 10 times with the atomically thin perovskite metasurfaces (1.2862 × 10 µm/RIU) than those without (918.9167 µm/RIU). The atomically thin perovskite nanomaterials with high absorption rates enable precise tuning of the depth of the plasmonic resonance dip. As such, one can optimize the structure to reach near zero-reflection at the resonance angle and the associated sharp phase singularity, which leads to a strongly enhanced GH lateral shift at the sensor interface. By integrating the 2D perovskite nanolayer into a metasurface structure, a strong localized electric field enhancement can be realized and GH sensitivity was further improved to 1.5458 × 10 µm/RIU. We believe that this enhanced electric field together with the significantly improved GH shift would enable single molecular or even submolecular detection for hard-to-identify chemical and biological markers, including single nucleotide mismatch in the DNA sequence, toxic heavy metal ions, and tumor necrosis factor-α (TNFα).
在这项工作中，我们基于原子级薄的钙钛矿纳米材料设计了高灵敏度的表面等离子体激元超敏传感器，对目标样品溶液的检测限高达10个折射率单位（RIU）。更重要的是，我们利用古斯-汉欣（GH）效应改进了相位奇点检测。已知GH位移与光学相位信号变化密切相关；在表面等离子体激元条件下，它比相位信号更灵敏、更尖锐，而实验测量装置比常用的干涉仪方案要紧凑得多，以获取相位信号。在此，我们已经证明，通过表面等离子体激元超敏传感器的最佳配置，表面等离子体激元灵敏度可以达到创纪录的高值1.2862×10 µm/RIU。由相位奇点引起的GH位移比其他超材料方案中所能达到的位移大三个数量级以上，包括银/二氧化钛双曲多层超材料（HMMs）、具有表面等离子体激元诱导透明（PIT）的金属-绝缘体-金属（MIM）多层波导以及具有大相位梯度的超表面器件。与没有原子级薄钙钛矿超表面（918.9167 µm/RIU）相比，原子级薄钙钛矿超表面使GH灵敏度提高了10倍以上（1.2862×10 µm/RIU）。具有高吸收率的原子级薄钙钛矿纳米材料能够精确调节表面等离子体激元共振凹陷的深度。因此，可以优化结构，使其在共振角处达到近零反射以及相关的尖锐相位奇点，这会导致传感器界面处的GH横向位移强烈增强。通过将二维钙钛矿纳米层集成到超表面结构中，可以实现强烈的局域电场增强，并且GH灵敏度进一步提高到1.5458×10 µm/RIU。我们相信，这种增强的电场以及显著改善的GH位移将能够对难以识别的化学和生物标志物进行单分子甚至亚分子检测，包括DNA序列中的单核苷酸错配、有毒重金属离子和肿瘤坏死因子-α（TNFα）。
