分类： 光学 >> 量子光学 提交时间： 2023-02-19
Li Tao
Zhiyong Li
Kun Chen
Yaoqiang Zhou
Hao Li
Ximiao Wang
Runze Zhan
Xiangyu Hou
Yu Zhao
Junling Xu
Teng Qiu
Xi Wan
Jian-Bin Xu
摘要： To develop highly sensitive, stable and repeatable surface-enhanced Raman scattering (SERS) substrates is crucial for analytical detection, which is a challenge for traditional metallic structures. Herein, by taking advantage of the high surface activity of 1T' transition metal telluride, we have fabricated high-density gold nanoparticles (AuNPs) that are spontaneously in-situ prepared on the 1T' MoTe2 atomic layers via a facile method, forming a plasmonic-2D material hybrid SERS substrate. This AuNP formation is unique to the 1T' phase, which is repressed in 2H MoTe2 with less surface activity. The hybrid structure generates coupling effects of electromagnetic and chemical enhancements, as well as excellent molecule adsorption, leading to the ultrasensitive (4*10^-17 M) and reproducible detection. Additionally, the immense fluorescence and photobleaching phenomena are mostly avoided. Flexible SERS tapes have been demonstrated in practical applications. Our approach facilitates the ultrasensitive SERS detection by a facile method, as well as the better mechanistic understanding of SERS beyond plasmonic effects.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Bo Tian
Jingyao Jiang
Ningsheng Xu
Zebo Zheng
Ximiao Wang
Shaojing Liu
Wuchao Huang
Tian Jiang
Huanjun Chen
Shaozhi Deng
摘要： Optical skyrmions, the optical analogue of topological configurations formed by three-dimensional vector fields covering the whole 4{\pi} solid angle but confined in a two-dimensional (2D) domain, have recently attracted growing interest due to their potential applications in high-density data transfer, storage, and processing. While the optical skyrmions have been successfully demonstrated using different field vectors in both of free-space propagating and near-field evanescent electromagnetic fields, the study on generation and control of the optical skyrmions, and their general correlation with the electromagnetic (EM) fields, are still in infancy. Here, we theoretically propose that an evanescent transverse-magnetic-polarized (TM-polarized) EM fields with rotational symmetry are actually N\'eel-type optical skyrmions of the electric field vectors. Such optical skyrmions maintain the rotation symmetry that are independent on the operation frequency and medium. Our proposal was verified by numerical simulations and real-space nano-imaging experiments performed on a graphene monolayer. Such a discovery can therefore not only further our understanding on the formation mechanisms of EM topological textures, but also provide a guideline for facile construction of EM skyrmions that may impact future information technologies.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Hyperbolic phonon polaritons (HPhPs) sustained in van der Waals (vdW) materials exhibit extraordinary capabilities of confining long-wave electromagnetic fields to the deep subwavelength scale. In stark contrast to the uniaxial vdW hyperbolic materials such as hexagonal boron nitride (h-BN), the recently emerging biaxial hyperbolic materials such as {\alpha}-MoO3 and {\alpha}-V2O5 further bring new degree of freedoms in controlling light at the flatland, due to their distinctive in-plane hyperbolic dispersion. However, the controlling and focusing of such in-plane HPhPs are to date remain elusive. Here, we propose a versatile technique for launching, controlling and focusing of in-plane HPhPs in {\alpha}-MoO3 with geometrically designed plasmonic antennas. By utilizing high resolution near-field optical imaging technique, we directly excited and mapped the HPhPs wavefronts in real space. We find that subwavelength manipulating and focusing behavior are strongly dependent on the curvature of antenna extremity. This strategy operates effectively in a broadband spectral region. These findings can not only provide fundamental insights into manipulation of light by biaxial hyperbolic crystals at nanoscale, but also open up new opportunities for planar nanophotonic applications.
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