All‐dielectric nanophotonics attracts ever increasing attention nowadays due to the possibility of controlling and configuring light scattering on high‐index semiconductor nanoparticles. It opens a room of opportunities for designing novel types of nanoscale elements and devices, and paves the way for advanced technologies of light energy manipulation. One of the exciting and promising prospects is associated with utilizing the so‐called toroidal moment, being the result of poloidal currents excitation, and anapole states, corresponding to the interference of dipole and toroidal electric moments. Here, higher‐order toroidal moments of both types (up to the electric octupole toroidal moment) are presented and investigated in detail via the direct Cartesian multipole decomposition allowing new near‐ and far‐field configurations to be obtained. Poloidal currents can be associated with vortex‐like distributions of the displacement currents inside nanoparticles, revealing the physical meaning of the high‐order toroidal moments and the convenience of the Cartesian multipoles as an auxiliary tool for analysis. High‐order nonradiating anapole states accompanied by the excitation of intense near‐fields are demonstrated. It is believed that the results are of high importance for both the fundamental understanding of light scattering by high‐index particles and a variety of nanophotonics applications and light governing on nanoscale.

All-dielectric metasurfaces comprising arrays of nanostructured high-refractive-index materials are re-imagining what is achievable in terms of the manipulation of light. However, the functionality of conventional dielectric-based metasurfaces is fixed by design; thus, their optical response is locked in at the fabrication stage. A far wider range of applications could be addressed if dynamic and reconfigurable control were possible. We demonstrate this here via the novel concept of hybrid metasurfaces, in which reconfigurability is achieved by embedding sub-wavelength inclusions of chalcogenide phase-change materials within the body of silicon nanoresonators. By strategic placement of an ultra-thin G e 2 S b 2 T e 5 layer and reversible switching of its phase-state, we show individual, multilevel, and dynamic control of metasurface resonances. We showcase our concept via the design, fabrication, and characterization of metadevices capable of dynamically filtering and modulating light in the near infrared (O and C telecom bands), with modulation depths as high as 70% and multilevel tunability. Finally, we show numerically how the same approach can be re-scaled to shorter wavelengths via appropriate material selection, paving the way to additional applications, such as high-efficiency vivid structural color generators in the visible spectrum. We believe that the concept of hybrid all-dielectric/phase-change metasurfaces presented in this work could pave the way for a wide range of design possibilities in terms of multilevel, reconfigurable, and high-efficiency light manipulation.

−1 ; d) Q factor of the fundamental magnetic dipole mode Q md for the same wavelength and r/L = 0.55; e) References for material parameters; f) Anisotropic, in-plane, and out-of-plane component, respectively; g) High-resistivity silicon; h) Measured data (Figure 2c).

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