Damir F. Yagudin’s research while affiliated with Lomonosov Moscow State University and other places

Single photon sources based on semiconductor quantum dots are one of the most prospective elements for optical quantum computing and cryptography. Such systems are often based on Bragg resonators, which provide several ways to control the emission of quantum dots. However, the fabrication of periodic structures with many thin layers is difficult. On the other hand, the coupling of single-photon sources with resonant nanoclusters made of high-index dielectric materials is known as a promising way for emission control. Our experiments and calculations show that the excitation of magnetic Mie-type resonance by linearly polarized light in a GaAs nanopillar oligomer with embedded InAs quantum dots leads to quantum emitters absorption efficiency enhancement. Moreover, the nanoresonator at the wavelength of magnetic dipole resonance also acts as a nanoantenna for a generated signal, allowing control over its radiation spatial profile. We experimentally demonstrated an order of magnitude emission enhancement and numerically reached forty times gain in comparison with unstructured film. These findings highlight the potential of quantum dots coupling with Mie-resonant oligomers collective modes for nanoscale single-photon sources development.

All-dielectric nanoparticle oligomers have recently emerged as promising candidates for nonlinear optical applications. Their highly resonant collective modes, however, are difficult to access by linearly polarized beams due to symmetry restraints. In this paper we propose a new way to increase the efficiency of nonlinear processes in all- dielectric oligomers by tightly focused azimuthally polarized cylindrical vector beam illumination. We demonstrate two orders enhancement of the third-harmonic gener- ation signal, governed by a collective optical mode represented by coherently excited out-of-plane magnetic dipoles. Crucially, the collective mode is characterized by strong electromagnetic field localization in the bulk of the nonlinear material. For comparison, we measure third-harmonic generation in the same oligomer pumped with linearly and radially polarized fundamental beams, which both show significantly lower harmonic output. We also provide numerical analysis to describe and characterize the observed effect. Our findings open new route to enhance and modulate the third-harmonic gen- eration efficiency of Mie-resonant isolated nanostructures by tailoring the polarization of the pump beam.

We investigate optical response of oligomers of dielectric nanodisks made of GaAs – anisotropic material with bulk quadratic nonlinearity. By using numerical approach, we analyse linear response of nanoparticle clusters in the vicinity of the magnetic dipole resonance for two types of incident radiation: linearly polarized plane wave and azimuthally polarized vector beams. Achieved results may be used to design highly efficient nonlinear optical nanoantennas with controllable radiation characteristics.

We demonstrated two orders of magnitude enhancement of the third-harmonic intensity for isolated nanoclusters of silicon nanoparticles illuminated by normally incident azimuthally polarized cylindrical vector beams at the wavelength of oligomer’s out-of-plane magnetic mode.

In article number 1900447, Andrey A. Fedyanin, Maria K. Kroychuk and co‐workers introduce a new concept of tailoring nonlinear properties of all‐dielectric nanoscale structures in accordance with the oligomers' point‐group symmetries while their linear scattering remains isotropic. This concept provides a viable path towards artificial anisotropic nonlinear systems, expanding the scope of their applications in nanophotonics.

The field of Mie‐resonant nanophotonics has attracted a lot of attention recently due to many promising applications in linear and nonlinear metaoptics. Optically induced magnetic resonances define novel characteristics of isolated high‐index dielectric nanoparticles and their oligomers. Here, the orientation‐dependent nonlinear frequency generation from dielectric oligomers with different symmetries, being all characterized by isotropic linear response, is demonstrated. The rotational dependence of the third‐harmonic signal emitted by the nanoparticle oligomers in accord with their point‐group symmetry (e.g., C3 or C4) is observed experimentally, while their linear scattering remains isotropic. The experimental data are in a good agreement with numerical simulations and the symmetry analysis of the nonlinear susceptibility tensor. The results open a new avenue for tailoring nonlinear properties of nanoscale structures.