Scholarlink

<p>Near-infrared surface lattice resonances (SLRs) in metal–dielectric–metal (MDM) metasurfaces have recently emerged as promising tools for refractive index (RI) sensing due to their strong field confinement and sharp resonance features. However, conventional strong coupling approaches typically suffer from significant optical losses, limiting sensor sensitivity and figure-of-merit (FOM). In this work, we introduce a weak-coupling mechanism in MDM metasurfaces that significantly reduces these losses, leading to enhanced sensing performance. We numerically investigate the SLR working in the near-infrared region enabled in the MDM plasmonic metasurfaces consisting of two-dimensional (2D) periodicity of silver (Ag) single-disk in each unit cell placed on the Ag layer, separated by a thin silicon dioxide (SiO<sub>2</sub>) spacing-layer. The structural parameters of the MDM plasmonic metasurfaces are designed and optimized using the finite-difference time-domain (FDTD) method, while its general optical resonance is analyzed by an approximation model. At resonances, which arise from the coupling between the in-plane Ag disks and the incidences, we observed high <i>Q</i>-factor reaching 777.9, low reflection (close to 0%), corresponding to high absorption (up to 100%), and high wavelength tunability of reflection spectra in the range of 1466.2–1711.3&#xa0;nm for the refractive indices of surrounding environment from in air to 1.20. In addition, the SLR enabled in dimer-disk cell MDM plasmonic metasurface are also proposed and then compared to a single-disk cell structure from the viewpoint of surface lattice resonances. Our analysis reveals that in terms of RI sensing performance, the single-disk cell structure is more advantageous in sensitivity and figure-of-merit (<i>FOM</i>) for the surrounding media with refractive indices from in air to 1.20, whereas the dimer-disk cell structure has higher contrast for the surrounding media with refractive indices from 1.20 to 1.45. The weak coupling between the in-plane plasmonic modes results in low Ohmic loss, which the refractometric biosensors show higher sensitivity of 1179.0&#xa0;nm⋅RIU<sup>−1</sup> and higher <i>FOM</i> of 320.7 RIU<sup>−1</sup> compared to other established MDM plasmonic metasurface biosensors based on strong coupling in-plane plasmonic modes and out-of-plane photonic modes. Our systematic investigation provides useful guidelines for the design of MDM plasmonic surface lattice resonant devices.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Near-infrared surface lattice resonances enabled in metal–dielectric–metal plasmonic metasurfaces for refractive index sensing

  • 期刊论文

  • 发表日期：

    2025年8月14日

查看全文
  • Huy Hieu Trung Le,
  • Xuan Bach Nguyen,
  • Thanh Son Pham,
  • Huu Tu Nguyen,
  • Anh Tu Tran,
  • Quang Minh Ngo

摘要

Near-infrared surface lattice resonances (SLRs) in metal–dielectric–metal (MDM) metasurfaces have recently emerged as promising tools for refractive index (RI) sensing due to their strong field confinement and sharp resonance features. However, conventional strong coupling approaches typically suffer from significant optical losses, limiting sensor sensitivity and figure-of-merit (FOM). In this work, we introduce a weak-coupling mechanism in MDM metasurfaces that significantly reduces these losses, leading to enhanced sensing performance. We numerically investigate the SLR working in the near-infrared region enabled in the MDM plasmonic metasurfaces consisting of two-dimensional (2D) periodicity of silver (Ag) single-disk in each unit cell placed on the Ag layer, separated by a thin silicon dioxide (SiO2) spacing-layer. The structural parameters of the MDM plasmonic metasurfaces are designed and optimized using the finite-difference time-domain (FDTD) method, while its general optical resonance is analyzed by an approximation model. At resonances, which arise from the coupling between the in-plane Ag disks and the incidences, we observed high Q-factor reaching 777.9, low reflection (close to 0%), corresponding to high absorption (up to 100%), and high wavelength tunability of reflection spectra in the range of 1466.2–1711.3 nm for the refractive indices of surrounding environment from in air to 1.20. In addition, the SLR enabled in dimer-disk cell MDM plasmonic metasurface are also proposed and then compared to a single-disk cell structure from the viewpoint of surface lattice resonances. Our analysis reveals that in terms of RI sensing performance, the single-disk cell structure is more advantageous in sensitivity and figure-of-merit (FOM) for the surrounding media with refractive indices from in air to 1.20, whereas the dimer-disk cell structure has higher contrast for the surrounding media with refractive indices from 1.20 to 1.45. The weak coupling between the in-plane plasmonic modes results in low Ohmic loss, which the refractometric biosensors show higher sensitivity of 1179.0 nm⋅RIU−1 and higher FOM of 320.7 RIU−1 compared to other established MDM plasmonic metasurface biosensors based on strong coupling in-plane plasmonic modes and out-of-plane photonic modes. Our systematic investigation provides useful guidelines for the design of MDM plasmonic surface lattice resonant devices.