Hamideddine Imane, Afkir Noureddine Ben, Refki Siham, Hayashi Shinji, Sekkat Zouheir
Optics & Photonics Pôle, MAScIR, University Mohammed VI Polytechnic, Benguerir, Morocco.
Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, 657-8501, Japan.
Sci Rep. 2025 Jul 1;15(1):21926. doi: 10.1038/s41598-025-05526-8.
We report on strong coupling between surface plasmons and excitons in an optically nonmetallic excitonic dye-polymer material of different thicknesses. We carried experiments of angular scans of reflectivity from silver and dye-polymer layers in a Kretshmann-Raether configuration, and we obtained the dispersive dielectric constant of the dye solutions for different dye concentrations using Lorentz model. The data obtained from our experiments, i.e. from reflectometry and absorption and dielectric dispersion, was used to perform rigorous electromagnetic calculations and finite difference time domaine numerical simulations of reflectivity and electric field distribution at the layers. Reflectometry calculations yielded dispersion relations of hybrid modes of propagating surface plasmons and excitons. The latter exhibit anticrossing which is the signature of strong coupling. The energy of Rabi splitting, [Formula: see text], is sample dependent, and is in the [Formula: see text] range, consistent with previously published experimental values of [Formula: see text] of the dye-polymer studied. The theoretical calculations and simulations support the experimental findings and demonstrate enhancement and subwavelength confinement of the optical field in the bulk of the dye-polymer film as well as at its surface. Strong coupling between surface plasmons and excitons is due to the field localization and enhancement as well as the sharp transition in the absorption spectrum of the excitonic material.
我们报道了在不同厚度的光学非金属激子染料 - 聚合物材料中表面等离子体激元和激子之间的强耦合。我们在Kretshmann - Raether配置下进行了银层和染料 - 聚合物层反射率的角度扫描实验，并使用洛伦兹模型获得了不同染料浓度下染料溶液的色散介电常数。从我们的实验中获得的数据，即来自反射测量、吸收和介电色散的数据，被用于对层的反射率和电场分布进行严格的电磁计算和时域有限差分数值模拟。反射测量计算得出了传播表面等离子体激元和激子的混合模式的色散关系。后者表现出反交叉，这是强耦合的特征。拉比分裂能量[公式：见原文]取决于样品，并且在[公式：见原文]范围内，与先前发表的所研究染料 - 聚合物的[公式：见原文]实验值一致。理论计算和模拟支持了实验结果，并证明了在染料 - 聚合物薄膜本体及其表面处光场的增强和亚波长限制。表面等离子体激元和激子之间的强耦合归因于场的局域化和增强以及激子材料吸收光谱中的急剧转变。
