多波段近场增强超材料与上转换材料的复合体系研究

Research on the Composite System of Multi-Band Near-Field Enhancement Metamaterials and Upconversion Materials

摘要: 为解决传统上转换材料(Upconversion Nanoparticles, UCNPs)转换效率低与常规超材料单波段共振且功能单一的局限，本文提出了一种银光栅–沟槽超材料与镱(Yb³⁺)和铒(Er³⁺)共掺杂的氟化钇钠(NaYF₄)相结合的复合结构。通过将NaYF₄:Er³⁺,Yb³⁺嵌入银光栅沟槽内部，在同一结构内实现了多波段共振吸收与特定波段的近场增强。通过时域有限差分法(Finite-Difference Time-Domain, FDTD)，本文系统研究了该复合结构在可见光(Visible, VIS)-近红外光(Near-Infrared, NIR)波段的光学响应特性，并明确了结构周期、光栅厚度、银层厚度对复合结构吸收峰位、局域场分布以及近场增强性能的调控规律。基于上述调控规律对复合结构进行优化后，该银光栅–沟槽超材料复合结构在400~1000n m波段内呈现出三个稳定的特征吸收峰，且在共振波长980 nm处实现了高达6.6 × 10⁶的增强因子。该复合结构对推动光电器件向小型化方向发展具有重要意义，在光谱探测、光伏器件和光通信等领域展现出独特的优势与广阔的应用前景。

Abstract: To address the limitations of conventional upconversion nanoparticles (UCNPs), such as low conversion efficiency, and conventional metamaterials, which typically exhibit single-band resonance and limited functionality, this study proposes a composite structure integrating silver-groove grating metamaterials with erbium (Er³⁺) and ytterbium (Yb³⁺) co-doped sodium yttrium fluoride (NaYF₄). By embedding NaYF₄:Er³⁺,Yb³⁺ within the grooves of the silver grating, multi-band resonant absorption and near-field enhancement at specific wavelengths are realized within a single architecture. Using the Finite-Difference Time-Domain (FDTD) method, this work systematically investigates the optical response characteristics of the composite structure across the Visible (VIS) to Near-Infrared (NIR) spectrum, and elucidates the influence of structural parameters—including periodicity, grating thickness, and silver layer thickness—on the absorption peaks, localized field distribution, and near-field enhancement performance. Through parameter optimization guided by the above analysis, the silver-groove grating metamaterial composite structure demonstrates three well-defined absorption peaks in the 400~1000 nm range, achieving an enhancement factor as high as 6.6 × 10⁶ at the resonance wavelength of 980 nm. This metamaterial configuration holds significant potential for advancing the miniaturization of optoelectronic devices and exhibits unique advantages and broad application prospects in fields such as spectral detection, photovoltaics, and optical communications.