Enhancement of inelastic light emission processes through resonant excitation usually correlates with enhanced scattering of the excitation light, as is for example typically the case for surface-enhanced fluorescence and Raman scattering from plasmonic nanostructures. Here, we demonstrate an unusual case where a reverse correlation is instead observed, that is, we measure a multifold enhancement of Raman emission along with suppressed elastic scattering. The system enabling this peculiar effect is composed of silicon nanodisks excited in the so-called anapole state, for which electric and toroidal dipoles interfere destructively in the far-field, thereby preventing elastic scattering, while the optical fields in the core of the silicon particles are enhanced, thus, amplifying light–matter interaction and Raman scattering at the Stokes-shifted emission wavelength. Our results demonstrate an unusual relation between resonances in elastic and inelastic scattering from nanostructures and suggest a route toward background-free frequency conversion devices.

中文翻译：

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硅纳米盘对偶极增强的本征拉曼散射

通过共振激发的非弹性发光过程的增强通常与激发光的散射增强相关，例如，典型的情况是表面增强的荧光和从等离子体纳米结构的拉曼散射。在这里，我们演示了一个不寻常的情况，而是观察到反向相关，也就是说，我们测量了拉曼发射的多重增强以及受抑制的弹性散射。产生这种特殊效果的系统由以所谓的偶极子态激发的硅纳米盘组成，为此，电偶极和环形偶极子在远场中产生破坏性干涉，从而防止了弹性散射，而硅颗粒核心中的光场被增强，因此，在斯托克斯位移的发射波长处放大光-物质相互作用和拉曼散射。我们的结果证明了纳米结构在弹性和非弹性散射中的共振之间存在不寻常的关系，并提出了通往无背景频率转换装置的途径。