Randerson Sam A, Zotev Panaiot G, Hu Xuerong, Knight Alexander J, Wang Yadong, Nagarkar Sharada, Hensman Dominic, Wang Yue, Tartakovskii Alexander I
Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, U.K.
Department of Physics, School of Physics, Engineering and Technology, University of York, York YO10 5DD, U.K.
ACS Nano. 2024 Jun 25;18(25):16208-16221. doi: 10.1021/acsnano.4c02178. Epub 2024 Jun 13.
Dielectric nanoresonators have been shown to circumvent the heavy optical losses associated with plasmonic devices; however, they suffer from less confined resonances. By constructing a hybrid system of both dielectric and metallic materials, one can retain low losses, while achieving stronger mode confinement. Here, we use a high refractive index multilayer transition-metal dichalcogenide WS exfoliated on gold to fabricate and optically characterize a hybrid nanoantenna-on-gold system. We experimentally observe a hybridization of Mie resonances, Fabry-Perot modes, and surface plasmon-polaritons launched from the nanoantennas into the substrate. We measure the experimental quality factors of hybridized Mie-plasmonic (MP) modes to be up to 33 times that of standard Mie resonances in the nanoantennas on silica. We then tune the nanoantenna geometries to observe signatures of a supercavity mode with a further increased factor of over 260 in experiment. We show that this quasi-bound state in the continuum results from strong coupling between a Mie resonance and Fabry-Perot-plasmonic mode in the vicinity of the higher-order anapole condition. We further simulate WS nanoantennas on gold with a 5 nm thick hBN spacer in between. By placing a dipole within this spacer, we calculate the overall light extraction enhancement of over 10, resulting from the strong, subwavelength confinement of the incident light, a Purcell factor of over 700, and high directivity of the emitted light of up to 50%. We thus show that multilayer TMDs can be used to realize simple-to-fabricate, hybrid dielectric-on-metal nanophotonic devices granting access to high-, strongly confined, MP resonances, along with a large enhancement for emitters in the TMD-gold gap.
已证明介电纳米谐振器可规避与等离子体器件相关的严重光学损耗；然而，它们的共振限制较差。通过构建介电和金属材料的混合系统，可以在保持低损耗的同时实现更强的模式限制。在此，我们使用在金上 exfoliated 的高折射率多层过渡金属二硫属化物 WS 来制造并对金上的混合纳米天线系统进行光学表征。我们通过实验观察到米氏共振、法布里 - 珀罗模式以及从纳米天线发射到衬底中的表面等离激元 - 极化激元的混合。我们测量了混合米氏 - 等离子体（MP）模式的实验品质因数，其高达二氧化硅上纳米天线中标准米氏共振的 33 倍。然后，我们调整纳米天线的几何形状，以观察在实验中具有超过 260 的进一步增加因子的超腔模式的特征。我们表明，这种连续统中的准束缚态是由高阶反极子条件附近的米氏共振与法布里 - 珀罗 - 等离子体模式之间的强耦合导致的。我们进一步模拟了在金上有 5 纳米厚 hBN 间隔层的 WS 纳米天线。通过在该间隔层内放置一个偶极子，我们计算出由于入射光的强亚波长限制、超过 700 的珀塞尔因子以及高达 50%的发射光高方向性，总体光提取增强超过 10。因此，我们表明多层过渡金属二硫属化物可用于实现易于制造的混合金属上介电纳米光子器件，该器件可实现高的、强限制的 MP 共振，以及在过渡金属二硫属化物 - 金间隙中对发射器的大幅增强。
