Vennberg Felix, Ravishankar Ajith Padyana, Anand Srinivasan
Applied Physics, KTH Royal Institute of Technology School of Engineering Sciences, Hannes Alféns väg 12, 114 19, Stockholm, Sweden.
Nanophotonics. 2022 Nov 11;11(21):4755-4764. doi: 10.1515/nanoph-2022-0605. eCollection 2022 Dec.
High index dielectric nanoresonators have gained prominence in nanophotonics due to lower losses compared to plasmonic systems and their ability to sustain both electric and magnetic resonances. The resonances can be engineered to create new types of optical states, such as bound-states in a continuum (BIC) and anapoles. In this work, we report on the optical properties of vertically stacked AlGaAs nanodisk Mie resonators. The nanodisks are designed to support an anapole state in the visible wavelength region (400-700 nm). The vertically stacked nanodisk resonators are fabricated from AlGaAs/GaAs multilayer samples with a fast and scalable patterning method using charged sphere colloidal lithography. Both measurements and finite difference time domain (FDTD) simulations of two and three stacked resonators show a sharp dip in the reflectance spectra at the anapole wavelength. For the 2 and 3 disk stacks the reflectance dip contrast at the anapole wavelength becomes very pronounced in the specular reflectance and is attributed to increased directional scattering due to an antenna effect. FDTD simulations show there is enhanced field confinement in all the disks at the anapole wavelength and the confined energy within the individual disks in the stack is at least 2-5 times greater compared to an isolated single nanodisk of the same dimension. Furthermore, the field confinement consistently increases with adding more disks in the stack. These vertically stacked AlGaAs nanodisk resonators can be a very exciting platform to engineer light matter interactions for linear and non-linear optical applications. The general principles of the fabrication method can be adapted to other wavelength ranges and can also be adapted for other III-V material combinations as well as for Si/SiO.
与等离子体系统相比，高折射率介电纳米谐振器因损耗较低且能够维持电谐振和磁谐振，在纳米光子学领域备受关注。这些谐振可以通过设计来创建新型光学状态，如连续统中的束缚态（BIC）和无偶极子。在这项工作中，我们报告了垂直堆叠的AlGaAs纳米盘米氏谐振器的光学特性。这些纳米盘被设计用于在可见光波长区域（400 - 700纳米）支持无偶极子状态。垂直堆叠的纳米盘谐振器由AlGaAs/GaAs多层样品通过使用带电球体胶体光刻的快速且可扩展的图案化方法制造而成。对两个和三个堆叠谐振器的测量以及时域有限差分（FDTD）模拟均显示，在无偶极子波长处的反射光谱中出现了尖锐的凹陷。对于2盘和3盘堆叠，无偶极子波长处的反射凹陷对比度在镜面反射中变得非常明显，这归因于天线效应导致的定向散射增加。FDTD模拟表明，在无偶极子波长处，所有盘内的场限制都得到了增强，并且堆叠中单个盘内的受限能量与相同尺寸的孤立单个纳米盘相比至少大2至5倍。此外，随着堆叠中盘的增加，场限制持续增强。这些垂直堆叠的AlGaAs纳米盘谐振器可能是一个非常令人兴奋的平台，可用于设计用于线性和非线性光学应用的光与物质相互作用。制造方法的一般原理可适用于其他波长范围，也可适用于其他III - V材料组合以及Si/SiO₂ 。
