Center for Nanophotonics, FOM Institute AMOLF , Science Park 104, 1098XG Amsterdam, The Netherlands.
ACS Nano. 2014 Jul 22;8(7):7350-8. doi: 10.1021/nn502469r. Epub 2014 Jun 23.
Similar to nanoparticles, nanoscale holes form a basic building block in a wide array of nanophotonic devices. Here we study the spectral and angular cathodoluminescence response of individual nanoholes with diameters ranging from 50 to 180 nm. Taking advantage of the deep-subwavelength excitation resolution, we find that the holes can be excited efficiently at the edge of the hole and that the response becomes stronger in the near-infrared part of the spectrum for larger holes. Using finite-difference time-domain simulations, we characterize the resonant modes inside the holes. We measure the angle-resolved cathodoluminescence response and observe strong beaming toward the side of electron beam excitation, complementary to what was shown for nanoparticles. The angular response can be explained by assuming a coherent superposition of radiating dipole moments, where the contribution of in-plane magnetic and electric dipole components increases for larger diameters.
类似于纳米粒子，纳米尺度的孔在各种纳米光子器件中形成了基本的构建块。在这里，我们研究了直径在 50 至 180nm 之间的单个纳米孔的光谱和角度阴极发光响应。利用深亚波长激发分辨率的优势，我们发现孔可以在孔的边缘被有效地激发，并且对于较大的孔，在光谱的近红外部分响应变得更强。使用有限差分时域模拟，我们对孔内的共振模式进行了特征描述。我们测量了角度分辨的阴极发光响应，并观察到在电子束激发的侧面有强烈的射束，这与纳米粒子的情况互补。可以通过假设辐射偶极矩的相干叠加来解释角度响应，其中对于较大的直径，平面内磁偶极子和电偶极子分量的贡献增加。
