Abstract
Based on the electromagnetic properties of all-dielectric optical metamaterial, an all-dielectric metasurface of lattice-perturbed nanohole array is proposed to excite a multiple Fano resonance in the near-infrared region. Combined with the group theory, the formation mechanism and evolution law of multiple Fano resonances in this structure when its unit cell is a square lattice configuration and the square lattice symmetry is broken are explored in depth. The results show that double degenerate mode directly excited by the normal incident plane wave is coupled to vertical free-space radiation continuum to form double Fano resonance when unit cell is symmetrical, while the uncoupled non-degenerate modes excited by the normal incident plane wave is coupled to vertical free-space radiation continuum to form triple Fano resonance with higher <i>Q</i> factor when the symmetry is broken. Numerical simulation is used to explore the influences of <i>x</i>-polarized and <i>y</i>-polarized plane wave on the above Fano resonances, and the results show that the Fano resonance of double degenerate resonance is polarization independent, while the non-degenerate resonance is polarization dependent. The findings in this work can provide an effective theoretical reference for designing other square lattice metasurface to realize the excitation and evolution of multiple Fano resonances.
Highlights
目前,国内外研究者们已经设计了大量形式新颖的 Fano 共振超构表面,按 组成材料可将其划分为等离子体型和全介质型,如 Kong 等人[10]提出了一种等 离子体超构表面与光学微腔相结合的复合结构,由微腔激发的多个窄带共振峰 与超构表面提供的连续背景散射态干涉形成多重 Fano 共振。Zhang 等人[11]提出 了一种非对称的纳米圆环与交叉纳米棒多聚体全介质超构表面,交叉纳米棒集 体振荡产生的电偶极米氏共振与纳米圆环提供的磁偶极米氏共振耦合形成单重 Fano 共振。当光学研究波段推进到近红外及可见光范围时,金属材料的欧姆损 耗及伴随其产生的热效应严重劣化了光学器件的效率,而全介质材料共振是由 位移电流而不是传导电流驱动,在该波段下几乎对光透明,这使得 Fano 共振超 构表面研究聚焦于全介质材料。面对形式各异的全介质超结构群体,深入探究 其中单重、双重乃至多重 Fano 共振的激发机理及演变规律显得尤其重要。.
一步探讨了正入射平面波的 xy 极化方向对上述五重 Fano 共振的影响, 结果表明,双重简并模式 Fano 共振偏振无关,三重非简并模式 Fano 共
基金: 国家自然科学基金项目(批准号:61201112)、河北省重点研发计划项目(批 准号:19273901D, 20373301D)、河北省自然科学基金(批准号:F2020203066)、中 国博士后基金项目(批准号:2018M630279)、河北省博士后择优资助项目(批准号: D2018003028)、河北省高等学校科学技术研究项目(批准号:ZD2018243)资助的课 题.
Summary
目前,国内外研究者们已经设计了大量形式新颖的 Fano 共振超构表面,按 组成材料可将其划分为等离子体型和全介质型,如 Kong 等人[10]提出了一种等 离子体超构表面与光学微腔相结合的复合结构,由微腔激发的多个窄带共振峰 与超构表面提供的连续背景散射态干涉形成多重 Fano 共振。Zhang 等人[11]提出 了一种非对称的纳米圆环与交叉纳米棒多聚体全介质超构表面,交叉纳米棒集 体振荡产生的电偶极米氏共振与纳米圆环提供的磁偶极米氏共振耦合形成单重 Fano 共振。当光学研究波段推进到近红外及可见光范围时,金属材料的欧姆损 耗及伴随其产生的热效应严重劣化了光学器件的效率,而全介质材料共振是由 位移电流而不是传导电流驱动,在该波段下几乎对光透明,这使得 Fano 共振超 构表面研究聚焦于全介质材料。面对形式各异的全介质超结构群体,深入探究 其中单重、双重乃至多重 Fano 共振的激发机理及演变规律显得尤其重要。. 一步探讨了正入射平面波的 xy 极化方向对上述五重 Fano 共振的影响, 结果表明,双重简并模式 Fano 共振偏振无关,三重非简并模式 Fano 共 基金: 国家自然科学基金项目(批准号:61201112)、河北省重点研发计划项目(批 准号:19273901D, 20373301D)、河北省自然科学基金(批准号:F2020203066)、中 国博士后基金项目(批准号:2018M630279)、河北省博士后择优资助项目(批准号: D2018003028)、河北省高等学校科学技术研究项目(批准号:ZD2018243)资助的课 题.
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