Jin Young-Ho, Oh Juntaek, Choi Wonshik, Kim Myung-Ki
KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Republic of Korea.
Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 02841, Republic of Korea.
Nanophotonics. 2022 Jan 4;11(9):2149-2158. doi: 10.1515/nanoph-2021-0653. eCollection 2022 Apr.
Exploiting multiple near-field optical eigenmodes is an effective means of designing, engineering, and extending the functionalities of optical devices. However, the near-field optical eigenmodes of subwavelength plasmonic nanostructures are often highly multiplexed in both spectral and spatial distributions, making it extremely difficult to extract individual eigenmodes. We propose a novel mode analysis method that can resolve individual eigenmodes of subwavelength nanostructures, which are superimposed in conventional methods. A transmission matrix is constructed for each excitation wavelength by obtaining the near-field distributions for various incident angles, and through singular value decomposition, near-field profiles and energy spectra of individual eigenmodes are effectively resolved. By applying transmission matrix analysis to conventional electromagnetic simulations, we clearly resolved a set of orthogonal eigenmodes of single- and double-slot nanoantennas with a slot width of 20 nm. In addition, transmission matrix analysis leads to solutions that can selectively excite specific eigenmodes of nanostructures, allowing selective use of individual eigenmodes.
利用多个近场光学本征模是设计、制造和扩展光学器件功能的有效手段。然而，亚波长等离子体纳米结构的近场光学本征模在光谱和空间分布上通常高度复用，使得提取单个本征模极其困难。我们提出了一种新颖的模式分析方法，该方法可以解析在传统方法中相互叠加的亚波长纳米结构的单个本征模。通过获取不同入射角的近场分布，为每个激发波长构建一个传输矩阵，并通过奇异值分解，有效地解析了单个本征模的近场分布和能谱。通过将传输矩阵分析应用于传统电磁模拟，我们清晰地解析了一组狭缝宽度为20纳米的单缝和双缝纳米天线的正交本征模。此外，传输矩阵分析得出的解决方案能够选择性地激发纳米结构的特定本征模，从而实现对单个本征模的选择性利用。
