Author Affiliations
Abstract
Bound states in the continuum (BICs) have exhibited extraordinary properties in photonics for enhanced light-matter interactions that enable appealing applications in nonlinear optics, biosensors, and ultrafast optical switches. The most common strategy to apply BICs in a metasurface is by breaking symmetry of resonators in the uniform array that leaks the otherwise uncoupled mode to free space and exhibits an inverse quadratic relationship between quality factor (Q) and asymmetry. Here, we propose a scheme to further reduce scattering losses and improve the robustness of symmetry-protected BICs by decreasing the radiation density with a hybrid BIC lattice. We observe a significant increase of radiative Q in the hybrid lattice compared to the uniform lattice with a factor larger than 14.6. In the hybrid BIC lattice, modes are transferred to Г point inherited from high symmetric X, Y, and M points in the Brillouin zone that reveal as multiple Fano resonances in the far field and would find applications in hyperspectral sensing. This work initiates a novel and generalized path toward reducing scattering losses and improving the robustness of BICs in terms of lattice engineering that would release the rigid requirements of fabrication accuracy and benefit applications of photonics and optoelectronic devices.
bound states in the continuum metasurfaces terahertz photonics radiative losses Fano resonances Opto-Electronic Science
2023, 2(4): 230006
燕山大学电气工程学院测试计量技术与仪器河北省重点实验室，河北 秦皇岛 066004
高值共振超表面以其对局域电磁场的显著增强而在纳米光子学中受到广泛关注。基于全介质材料独特的电磁属性，提出了一种方形晶格对称性破缺的全介质纳米孔阵列超表面，通过打破方形晶格原胞的面内对称性来激发近红外区域的高值Fano共振。在垂直入射平面波的激发下，该超表面实现了极化独立的双重简并模态Fano共振以及极化依赖的三重非简并模态Fano共振，后者具有更高的值与更强的电磁局域性能。采用数值模拟探究了晶格扰动参数对三重非简并模态Fano共振特性的影响。结果表明，三重非简并模态Fano共振的值与局域电场强度受晶格扰动参数控制，通过优化晶格扰动参数，三重非简并模态Fano共振的值可同时高达，，，其局域电场强度可同时高达，，。
表面光学 光学超表面 多重Fano共振 方形晶格 高Q值 电磁局域增强 光学学报
2022, 42(15): 1524001
1 贵州师范大学大数据与计算机科学学院，贵州 贵阳 550000
2 华中师范大学物理科学与技术学院，湖北 武汉 430079
3 喀什大学物理与电气工程学院，新疆 喀什 844007
利用环偶极子超材料的奇异特性实现了高Q值Fano共振的设计。该亚波长结构是通过两个不对称开口谐振环实现的，在9.1 GHz处实现了高Q值Fano共振。通过对超材料传输特性、结构表面电流、涡旋磁场以及各多极子的远场散射能量分析可知，所设计的Fano共振是由结构内迅速增加的环偶极子产生的。分析了在垂直入射电磁波的不同极化角下，Fano共振与多极子散射能量的变化关系。所设计的平面环偶极子超材料Fano共振在微波段、太赫兹甚至光波段具有潜在的应用价值，如超高灵敏度传感器、光开关等。
材料 环偶极子 Fano共振 高Q值 散射能量 激光与光电子学进展
2021, 58(9): 0916001
1 湖南大学 物理与电子学院, 湖南 长沙 410082
2 长沙市第一铁路中学, 湖南 长沙 410001
利用FDTD研究了Ag-SiO2纳米结构的法诺共振。mj(j=2,3)模的共振峰随银膜水平长度l的增长而红移。 法诺共振与银-空气、SiO2周期结构和SiO2有关。随着SiO2横向长度L的增加,法诺现象越来越明显。此外, 法诺共振还与银膜的介电常数（实部的负值-ε′m）密切相关。在非周期性Ag-空气-氧化硅结构中, 当-ε′m＝4 000和-ε′m=6 000时, 可以观察到明显的法诺共振。
法诺共振 银-空气-氧化硅 纳米结构 Fano resonances Ag-Air-SiO2 nanostructure
天津理工大学电气电子工程学院薄膜电子与通信器件天津市重点实验室, 天津300384
设计了玻璃基底上的边对边型纳米棒聚合体周期性阵列结构,研究其磁共振机理,并用以实现Fano型共振。在横向激励下,即外加电场垂直于纳米棒长轴时,平面型纳米棒三聚体可实现单次Fano共振,而金属-绝缘体-金属型(MIM)纳米棒聚合体可实现双Fano共振。采用有限元法模拟分析了聚合体阵列在可见光至近红外波段内的近场电磁分布和远场消光谱,研究了其共振峰的特性与实现机理。分析表明,纳米棒局域表面等离激元共振模式的近场耦合与叠加,激发其磁表面等离激元(MSPs),从而得到Fano型共振。尤其MIM纳米棒的引入,为双次乃至多次Fano共振的实现提供更多可能。所设计纳米棒聚合体阵列的Fano共振损耗小,品质高,其带宽仅为30~50 nm,有望应用于多波长生化传感检测、光开关等器件中。
光电子学 纳米棒 双Fano共振 横向激励 金属-绝缘体-金属 激光与光电子学进展
2019, 56(1): 012501
Author Affiliations
Abstract
University of Paderborn, Department of Physics, Paderborn, Germany
Free from phase-matching constraints, plasmonic metasurfaces have contributed significantly to the control of optical nonlinearity and enhancement of nonlinear generation efficiency by engineering subwavelength meta-atoms. However, high dissipative losses and inevitable thermal heating limit their applicability in nonlinear nanophotonics. All-dielectric metasurfaces, supporting both electric and magnetic Mie-type resonances in their nanostructures, have appeared as a promising alternative to nonlinear plasmonics. High-index dielectric nanostructures, allowing additional magnetic resonances, can induce magnetic nonlinear effects, which, along with electric nonlinearities, increase the nonlinear conversion efficiency. In addition, low dissipative losses and high damage thresholds provide an extra degree of freedom for operating at high pump intensities, resulting in a considerable enhancement of the nonlinear processes. We discuss the current state of the art in the intensely developing area of all-dielectric nonlinear nanostructures and metasurfaces, including the role of Mie modes, Fano resonances, and anapole moments for harmonic generation, wave mixing, and ultrafast optical switching. Furthermore, we review the recent progress in the nonlinear phase and wavefront control using all-dielectric metasurfaces. We discuss techniques to realize all-dielectric metasurfaces for multifunctional applications and generation of second-order nonlinear processes from complementary metal–oxide–semiconductor-compatible materials.
nonlinear optics dielectric metasurfaces Mie modes Fano resonances anapole modes harmonic generation Advanced Photonics
2019, 1(2): 024002
Author Affiliations
Abstract
Engineering Research Center of Gansu Province for Intelligent Information Technology and Application, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
A refractive index sensor based on Fano resonances in metal-insulator-metal (MIM) waveguides coupled with rectangular and dual side rings resonators is proposed. The sensing properties are numerically simulated by the finite element method (FEM). For the interaction of the narrow-band spectral response and the broadband spectral response caused by the side-coupled resonators and the rectangular resonator, respectively, the transmission spectra exhibit a sharp and asymmetric profile. Results are analyzed using the coupled-mode theory based on the transmission line theory. The coupled mode theory is employed to explain the Fano resonance effect. The results show that with an increase in the refractive index of the fill dielectric material in the slot of the system, the Fano resonance peak exhibits a remarkable red shift. Through the optimization of structural parameters, we achieve a theoretical value of the refractive index sensitivity (S) as high as 1160 nm/RIU, and the corresponding sensing resolution is 8.62 × 10-5 RIU. In addition, the coupled MIM waveguide structure can be easily extended to other similar compact structures to realize the sensing task and integrated with other photonic devices at the chip scale. This work paves the way toward the sensitive nanometer scale refractive index sensor for design and application.
Refractive index sensor Fano resonances surface plasmon polaritons MIM waveguides Photonic Sensors
2018, 8(4): 04367
基于表面等离子激元理论提出一个由金属-介质-金属波导和半环切口组成的波导结构,应用时域有限差分法研究了该结构的透射特性.仿真结果表明：透射光谱中产生一个类似法诺共振线形的共振谷, 该法诺共振由半环切口中连续态与离散态的相互干涉所致, 其共振波长可以通过改变半环切口的结构参量进行调节, 该结构灵敏度约为575 nm/RIU, 品质因数可达5 671.添加一个矩形谐振腔于该结构上可产生多重法诺共振, 品质因数为6 555, 此特征能为波导结构的设计提供极大的灵活性,有望在光学集成回路、纳米传感器方面得到比较广泛的应用.
表面等离子激元 纳米传感器 时域有限差分法 法诺共振 半环切口 波导结构 Surface plasmon polaritons Nano sensor Finite-difference time-domain method Fano resonances Semi-ring stub Fano resonance
郑州大学物理工程学院材料物理教育部重点实验室,郑州 450052
Fano共振效应是一种具有非对称线型的共振散射现象,起源于共振过程和非共振过程的量子干涉效应。近年来,在等离子体纳米结构中Fano共振现象也被发现,并成为纳米光子学的一个研究热点。等离子体Fano共振通常具有较窄的光谱线宽,且不能直接与入射光耦合,只能局域在近场,强的近场局域特性可以获得巨大的表面电磁场增强。由于等离子体Fano共振独特的光学特性,已经被应用到单分子探测、高灵敏度传感、增强光谱、完美吸收、电磁诱导透明和慢光光子学器件等众多领域当中。
Fano共振 等离子体纳米结构 纳米光子学 Fano resonances plasmonic nanostructures nanophotonics
