European Laboratory for Nonlinear Spectroscopy, via Nello Carrara 1, 50019, Sesto Fiorentino, FI, Italy.
Department of Physics, University of Florence, via Sansone 1, 50019, Sesto Fiorentino, FI, Italy.
Nat Commun. 2018 Jan 26;9(1):396. doi: 10.1038/s41467-018-02855-3.
The optical behavior of coupled systems, in which the breaking of parity and time-reversal symmetry occurs, is drawing increasing attention to address the physics of the exceptional point singularity, i.e., when the real and imaginary parts of the normal-mode eigenfrequencies coincide. At this stage, fascinating phenomena are predicted, including electromagnetic-induced transparency and phase transitions. To experimentally observe the exceptional points, the near-field coupling to waveguide proposed so far was proved to work only in peculiar cases. Here, we extend the interference detection scheme, which lies at the heart of the Fano lineshape, by introducing generalized Fano lineshapes as a signature of the exceptional point occurrence in resonant-scattering experiments. We investigate photonic molecules and necklace states in disordered media by means of a near-field hyperspectral mapping. Generalized Fano profiles in material science could extend the characterization of composite nanoresonators, semiconductor nanostructures, and plasmonic and metamaterial devices.
耦合系统的光学行为引起了越来越多的关注，因为它涉及到异常点奇异点的物理性质，即当正常模式本征频率的实部和虚部重合时。在这个阶段，人们预测了一些引人入胜的现象，包括电磁感应透明和相变。为了实验观察异常点，目前提出的对波导的近场耦合被证明仅在特殊情况下有效。在这里，我们通过引入广义的 Fano 线型作为共振散射实验中异常点发生的特征，扩展了处于 Fano 线型核心的干涉检测方案。我们通过近场高光谱映射研究了无序介质中的光子分子和项链态。材料科学中的广义 Fano 轮廓可以扩展对复合纳米谐振器、半导体纳米结构以及等离子体和超材料器件的特性描述。
