Tellurium nanoparticles are used for broadband solar energy harvesting and efficient photothermal conversion.

Strong Coulomb interactions in monolayer transition metal dichalcogenides (TMDs) produce strongly bound excitons, trions, and biexcitons. The existence of multiexcitonic states has drawn tremendous attention because of its promising applications in quantum information. Combining different monolayer TMDs into van der Waals (vdW) heterostructures opens up opportunities to engineer exciton devices and bring new phenomena. Spatially separated electrons and holes in different layers produce interlayer excitons. Although much progress has been made on excitons in single layers, how interlayer excitons contribute the photoluminescence emission and how to tailor the interlayer exciton emission have not been well understood. Here, room temperature strong coupling between interlayer excitons in the WS 2 /MoS 2 vdW heterostructure and cavity‐enhanced Mie resonances in individual silicon nanoparticles (Si NPs) are demonstrated. The heterostructures are inserted into a Si film‐Si NP all‐dielectric platform to realize effective energy exchanges and Rabi oscillations. Besides mode splitting in scattering, tunable interlayer excitonic emission is also observed. The results make it possible to design TMDs heterostructures with various excitonic states for future photonics devices.

The photoluminescence of WS2 flakes can be manipulated by an individual Si nanoparticle.

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Recently, all-dielectric materials (ADMs), especially with a high value of the refractive index, are emerging as a promising alternative to plasmonic nanostructures for nanophotonics applications. [9][10][11] Comparing to metallic plasmonic nanostructures, ADMs are superior in low-loss, ultralow light-into-heat conversion [12] and the excitation of both electric and strong magnetic resonances. [13] As a basic building block, high-index ADMs such as silicon [14][15][16][17] (Si), gallium arsenide [18] (GaAs), aluminum gallium arsenide [19] (AlGaAs), and so on have attracted more and more attentions. Among them, Si is the most widely studied one because of its abundance and mature processing technology. Directional infrared and visible light scattering by individual nanoparticles have been first experimentally demonstrated by Geffrin et al. [20] and Fu et al. [15] for Si and by Person et al. [18] for GaAs. At a certain wavelength, the forward-to-backward scattering ratio reaches above six for an individual Si nanoparticle. [15] However, at the peak of scattering cross-section spectrum, the directionality decreases greatly and becomes inefficient. Further, Yan et al. [21] observed the directional Fano resonance in Si nanoparticle dimers in the experiments. The forward-to-backward scattering ratio can be ≈64 at the scattering peak relying on the directional Fano resonance. Besides, magnetically induced forward scattering at visible wavelengths in silicon nanoparticle oligomers has also been demonstrated. [22] Other linear and nonlinear optical properties of Si nanoparticles have been studied in detail by Kivshar and co-workers. [23][24][25] On the contrary, Ge with one of the highest refractive indices has not gotten enough attention, especially in the visible region. Comparing with Si, Ge has a smaller bandgap (E g, Ge = 0.66 eV, E g, Si = 1.12 eV) and higher hole and electron mobilities (4.2 and 2.6 times of Si, respectively). [26] Thus, it is widely used for high-performance photodetection and transistor. In addition, the excitonic Bohr radius of Ge (24.3 nm) is larger than that of Si (4.9 nm), which results in more prominent quantum confinement effects. In optics, Ge has stronger light absorption in the visible region and can be used as a photothermal material by virtue of its higher refractive index and extinction coefficient than silicon. [27] Moreover, the thirdorder nonlinear optical coefficient of Ge is one order of magnitude greater than Si, which makes it more efficient in nonlinear optics. [28] The electric and magnetic dipolar responses of Previous designs of photonic nanoantennas are based on noble metal plasmonic structures, suffering from large ohmic loss and only possessing dipolar plasmon modes. This has driven the intense search for all-dielectric materials (ADMs) beyond noble metals. Here, for the first time, a strong scattering anisotropy in a Ge nanosphere is demonstrated in the visible and nearinfrared regions. The forward-to-backward scattering ratio for an individual Ge nanosphere (150 nm) ca...