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The non-Hermitian nature of confined photonic modes is described by the electric complex modal volume, V E , which represents a key parameter that leads to counterintuitive effects, such as negative modal contribution to the local density of states and non-Lorentzian lineshapes. Here, we address the magnetic counterpart of V E by means of near-field perturbation experiments in a photonic crystal slab cavity. We study the relevant role played by the imaginary part of the magnetic modal volume, V H , which can increase the quality factor of the confined modes by means of a local external magnetic perturbation. We show how a mapping of the spatial distribution of both the real and imaginary parts of V H can be inferred by near-field experiments employing Al-covered near-field tips. Our findings deepen the role of the magnetic component of light and could open a new route in employing metamaterials, magnetic quantum emitters, and topological photonics.

We use low-resolution optical lithography joined with solid state dewetting of crystalline, ultra-thin silicon on insulator (c-UT-SOI) to form monocrystalline, atomically smooth, silicon-based Mie resonators in well-controlled large periodic arrays. The dewetted islands have a typical size in the 100 nm range, about one order of magnitude smaller than the etching resolution. Exploiting a 2 µm thick SiO2 layer separating the islands and the underlying bulk silicon wafer, we combine the resonant modes of the antennas with the etalon effect. This approach sets the resonance spectral position and improves the structural colorization and the contrast between scattering maxima and minima of individual resonant antennas. Our results demonstrate that templated dewetting enables the formation of defect-free, faceted islands that are much smaller than the nominal etching resolution and that an appropriate engineering of the substrate improves their scattering properties. These results are relevant to applications in spectral filtering, structural color and beam steering with all-dielectric photonic devices.

Disordered photonic nanostructures have attracted tremendous interest in the past three decades, not only due to the fascinating and complex physics of light transport in random media, but also for peculiar functionalities in a wealth of interesting applications. Recently, the interest in dielectric disordered systems has received new inputs by exploiting the role of long‐range correlation within scatterer configurations. Hyperuniform photonic materials, that share features of photonic crystals and random systems, constitute the archetype of systems where light transport can be tailored from diffusive transport to a regime dominated by light localization due to the presence of photonic band gap. Here, advantage is taken of the combination of the hyperuniform disordered (HuD) design in slab photonics, the use of embedded quantum dots for feeding the HuD resonances, and near‐field hyperspectral imaging with sub‐wavelength resolution in the optical range to explore the transition from localization to diffusive transport. It is shown, theoretically and experimentally, that photonic HuD systems support resonances ranging from strongly localized modes to extended modes. It is demonstrated that Anderson‐like modes with high Q/V are created, with small footprint, intrinsically reproducible and resilient to fabrication‐induced disorder, paving the way for a novel photonic platform for quantum applications.

All-dielectric sub-micrometric particles have been successfully exploited for light management in a plethora of applications at visible and near-infrared frequencies. However, the investigation of the intricacies of the Mie resonances at the sub-wavelength scale has been hampered by the limitations of conventional near-field methods. In this paper, we address the spatial and spectral mapping of multipolar modes of a Si island by hyper-spectral imaging. The simultaneous detection of several resonant modes allows us to clarify the role of the substrate and the incidence angle of the impinging light, highlighting spectral splitting of the quadrupolar mode and resulting in different spatial features of the field intensity. We explore theoretically and experimentally such spatial features. Details as small as 200 nm can be detected and agree with simulations based on the finite difference time domain method. Our results are relevant to near-field imaging of dielectric structures, the comprehension of the resonant features of sub-micrometric Mie antennas, beam steering, and the resonant coupling with light emitters. Our analysis suggests a novel approach to control the absorption of a single emitter in the framework of surface enhanced absorption or stimulated emission applications.