Ultra-subwavelength phase-sensitive Fano-imaging of localized photonic modes
Ultra-subwavelength phase-sensitive Fano-imaging of localized photonic modes
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DOI：
10.1038/lsa.2015.99
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发表时间：
2015-09-01
影响因子：
19.4
通讯作者：
Gurioli, Massimo
中科院分区：
文献类型：
--
作者：
Caselli, Niccolo;Intonti, Francesca;Gurioli, Massimo
光子和等离子体器件依赖于介电和金属环境中局部光态密度 (LDOS) 的纳米级控制。设计和定制纳米谐振器电 LDOS 方面的巨大进步需要一种研究工具，能够以深亚波长空间分辨率获取光学局域谐振模式的详细特征。这种情况激发了不同纳米级成像技术的发展。在这里，我们证明了一种将扫描近场光学显微镜与共振散射光谱相结合的技术，能够通过基于光散射的纯光学方法以出色的空间分辨率 (lambda/19) 对纳米共振器中的电 LDOS 进行成像。使用这种技术，我们研究了光子晶体纳米腔的特性，证明谐振模式表现为由干涉产生的特征性法诺线形状。因此，通过监测法诺线形状的空间变化，我们可以局部测量谐振模式的相位调制，而无需外部外差检测。这种新颖的深亚波长成像方法使我们能够获得局部电场的强度和相位调制。最后，该技术可以在任何类型的平台上实施，对于基于非光学活性材料（例如硅、玻璃、聚合物或金属）的平台特别有吸引力。
Photonic and plasmonic devices rely on nanoscale control of the local density of optical states (LDOS) in dielectric and metallic environments. The tremendous progress in designing and tailoring the electric LDOS of nano-resonators requires an investigation tool that is able to access the detailed features of the optical localized resonant modes with deep-subwavelength spatial resolution. This scenario has motivated the development of different nanoscale imaging techniques. Here, we prove that a technique involving the combination of scanning near-field optical microscopy with resonant scattering spectroscopy enables imaging the electric LDOS in nano-resonators with outstanding spatial resolution (lambda/19) by means of a pure optical method based on light scattering. Using this technique, we investigate the properties of photonic crystal nanocavities, demonstrating that the resonant modes appear as characteristic Fano line shapes, which arise from interference. Therefore, by monitoring the spatial variation of the Fano line shape, we locally measure the phase modulation of the resonant modes without the need of external heterodyne detection. This novel, deep-subwavelength imaging method allows us to access both the intensity and the phase modulation of localized electric fields. Finally, this technique could be implemented on any type of platform, being particularly appealing for those based on non-optically active material, such as silicon, glass, polymers, or metals.