Polarization-sensitive cathodoluminescence Fourier microscopy
Polarization-sensitive cathodoluminescence Fourier microscopy
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DOI：
10.1364/oe.20.018679
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发表时间：
2012-08-13
期刊：
影响因子：
3.8
通讯作者：
Polman, Albert
中科院分区：
文献类型：
--
作者：
Coenen, Toon;Polman, Albert
确定亚波长结构如光学纳米天线、纳米腔和光子晶体的发射偏振特性对于理解它们的物理特性和优化它们在应用中的使用是重要的。最近，我们已经表明，角分辨阴极发光成像光谱（ARCIS），它使用30 keV的电子束作为激发源，是一个有用的技术来研究这种结构的远场特性。在这里，我们扩展的技术与偏振敏感的角度检测。作为原理证明，我们实验探测的三个正交的偶极发射器的偏振是众所周知的，并找到实验和理论之间的良好协议的发射偏振特性。我们通过激发非结构化的金表面和脊纳米天线与面内偶极等离子体共振来访问这些偶极取向。光发射用铝半抛物面镜收集。我们展示了如何考虑抛物面反射镜对发射偏振的影响，以及如何在已知发射偏振的情况下预测偏振滤波图案。此外，我们还计算了在光路中引入狭缝可以大大提高阴极射线发光光谱的偏振对比度。最后，我们从实验数据重建的发射极化，并表明，从这些场模式，我们可以推断的诱导偶极矩的方向。测量发射偏振的能力，结合对光学状态的局部密度的灵敏度，宽光谱范围和高激发分辨率，可以用于非常详细地研究光子纳米结构。(C)2012美国光学学会
Determining the emission polarization properties of sub-wavelength structures like optical nanoantennas, nanocavities and photonic crystals is important to understand their physical properties and to optimize their use in applications. Recently we have shown that angle-resolved cathodoluminescence imaging spectroscopy (ARCIS), which uses a 30 keV electron beam as an excitation source, is a useful technique to study the far-field properties of such structures. Here we extend the technique with polarization-sensitive angular detection. As proof-of-principle, we experimentally probe the emission polarization properties of three orthogonal dipolar emitters of which the polarization is well-known and find excellent agreement between experiment and theory. We access these dipole orientations by exciting an unstructured gold surface and a ridge nanoantenna with an in-plane dipolar plasmon resonance. The light emission is collected with an aluminum half paraboloid mirror. We show how to take the effect of the paraboloid mirror on the emission polarization into account and how to predict the polarization-filtered pattern if the emission polarization is known. Furthermore, we calculate that by introducing a slit in the beam path the polarization contrast in cathodoluminescence spectroscopy can be strongly enhanced. Finally, we reconstruct the emission polarization from the experimental data and show that from these field patterns we can infer the orientation of the induced dipole moment. The ability to measure the emission polarization, in combination with the sensitivity to the local density of optical states, broad spectral range and high excitation resolution, can be employed to study photonic nanostructures in great detail. (C) 2012 Optical Society of America