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Strongly coupled evenly divided disks: a new compact and tunable platform for plasmonic Fano resonances
摘要： Plasmonic artificial molecules are promising platforms for linear and nonlinear optical modulation at various regimes including the visible, infrared and terahertz bands. Fano resonances in plasmonic artificial structures are widely used for controlling spectral lineshapes and tailoring of near-field and far-field optical response. Generation of a strong Fano resonance usually relies on strong plasmon coupling in densely packed plasmonic structures. Challenges in reproducible fabrication using conventional lithography significantly hinders the exploration of novel plasmonic nanostructures for strong Fano resonance. In this work, we propose a new class of plasmonic molecules with symmetric structure for Fano resonances, named evenly divided disk, which shows a strong Fano resonance due to the interference between a subradiant anti-bonding mode and a superradiant bonding mode. We successfully fabricated evenly divided disk structures with high reproducibility and with sub-20-nm gaps, using our recently developed sketch and peel lithography technique. The experimental spectra agree well with the calculated response, indicating the robustness of the Fano resonance for the evenly divided disk geometry. Control experiments reveal that the strength of the Fano resonance gradually increases when increasing the number of split parts on the disk from 3 to 8 individual segments. The Fano-resonant plasmonic molecules that can also be reliably defined by our unique fabrication approach open up new avenues for application and provide insight into the design of artificial molecules for controlling light-matter interactions.
关键词： sketch and peel lithography,artificial molecules,Fano resonance,plasmon coupling,tiny gap
更新于2025-09-23 15:21:01
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Strongly coupled, high-quality plasmonic dimer antennas fabricated using a sketch-and-peel technique
摘要： A combination of helium- and gallium-ion beam milling together with a fast and reliable sketch-and-peel technique is used to fabricate gold nanorod dimer antennas with an excellent quality factor and with gap distances of less than 6 nm. The high fabrication quality of the sketch-and-peel technique compared to a conventional ion beam milling technique is proven by polarisation-resolved linear dark-field spectromicroscopy of isolated dimer antennas. We demonstrate a strong coupling of the two antenna arms for both fabrication techniques, with a quality factor of more than 14, close to the theoretical limit, for the sketch-and-peel–produced antennas compared to only 6 for the conventional fabrication process. The obtained results on the strong coupling of the plasmonic dimer antennas are supported by finite-difference time-domain simulations of the light-dimer antenna interaction. The presented fabrication technique enables the rapid fabrication of large-scale plasmonic or dielectric nanostructures arrays and metasurfaces with single-digit nanometer scale milling accuracy.
关键词： helium-ion beam lithography,near-field enhancement,strong coupling,plasmonic nanostructures,sketch and peel,quality factor,single-particle dark-field spectroscopy
更新于2025-09-16 10:30:52
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Adhesion‐Engineering‐Enabled “Sketch and Peel” Lithography for Aluminum Plasmonic Nanogaps
摘要： Aluminum is one of the most significant plasmonic materials for its advantage of low cost, natural abundance, as well as the ultraviolet optical response. However, it is still very challengeable for the fabrication of aluminum plasmonic nanogaps, which greatly limits the applications of aluminum plasmonics considering the essential role of nanogaps for electric field enhancement. Here, the reliable patterning of aluminum plasmonic nanogaps employing a modified “Sketch and Peel” lithography strategy is demonstrated. By introducing a self-assembled monolayer to engineer the surface energy of the substrate, the adhesiveness of the aluminum film outside outline template is significantly decreased to implement the selective peeling process. Besides, the near-infrared Fano resonance in the periodic aluminum heptamers has been first revealed by enabling the strong electric field and plasmon coupling in the aluminum nanostructures with 10 nm scale nanogaps. In addition, surface-enhanced Raman spectroscopy and infrared spectroscopy are also illustrated in the rationally designed aluminum dimers. The present work provides a robust method to obtain aluminum plasmonic nanogaps, which may play an important role on the practical applications of aluminum plasmonics, such as surface-enhanced vibration spectroscopy and nonlinear optics.
关键词： surface-enhanced spectroscopy,aluminum plasmonics,Sketch and Peel lithography,adhesion engineering,plasmonic nanogaps
更新于2025-09-12 10:27:22