Lin Linhan, Lepeshov Sergey, Krasnok Alex, Huang Yu, Jiang Taizhi, Peng Xiaolei, Korgel Brian A, Alù Andrea, Zheng Yuebing
State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, P. R. China.
Department of Electrical and Photonics Engineering, DTU Electro, Technical University of Denmark, Building 343, Lyngby, DK-2800 Kgs, Denmark.
Adv Sci (Weinh). 2025 Mar;12(10):e2412454. doi: 10.1002/advs.202412454. Epub 2025 Jan 21.
Fano resonances in photonics arise from the coupling and interference between two resonant modes in structures with broken symmetry. They feature an uneven and narrow and tunable lineshape and are ideally suited for optical spectroscopy. Many Fano resonance structures have been suggested in nanophotonics over the last ten years, but reconfigurability and tailored design remain challenging. Herein, an all-optical "pick-and-place" approach aimed at assembling Fano metamolecules of various geometries and compositions in a reconfigurable manner is proposed. Their coupling behavior by in situ dark-field scattering spectroscopy is studied. Driven by a light-directed opto-thermoelectric field, silicon nanoparticles with high-quality-factor Mie resonances (discrete states) and low-loss BaTiO nanoparticles (continuum states) are assembled into all-dielectric heterodimers, where distinct Fano resonances are observed. The Fano parameter can be adjusted by changing the resonant frequency of the discrete states or the light polarization. Tunable coupling strength and multiple Fano resonances by altering the number of continuum states and discrete states in dielectric heterooligomers are also shown. This work offers a general design rule for Fano resonance and an all-optical platform for controlling Fano coupling on demand.
光子学中的法诺共振源于对称性破缺结构中两个共振模式之间的耦合和干涉。它们具有不均匀、狭窄且可调谐的线形，非常适合用于光谱学。在过去十年中，纳米光子学领域已经提出了许多法诺共振结构，但可重构性和定制设计仍然具有挑战性。在此，我们提出了一种全光“拾取与放置”方法，旨在以可重构的方式组装各种几何形状和组成的法诺超分子。通过原位暗场散射光谱研究了它们的耦合行为。在光控光热电场的驱动下，具有高品质因子米氏共振（离散态）的硅纳米颗粒和低损耗的钛酸钡纳米颗粒（连续态）被组装成全介质异二聚体，在其中观察到了明显的法诺共振。通过改变离散态的共振频率或光的偏振，可以调节法诺参数。通过改变介电异寡聚体中连续态和离散态的数量，还展示了可调谐的耦合强度和多个法诺共振。这项工作为法诺共振提供了一个通用的设计规则，并为按需控制法诺耦合提供了一个全光平台。
