Integrated
nanophotonics

The development of nanophotonics systems for the manipulation of luminescent properties of single quantum emitters is essential for quantum communication and computing. Dielectric nanosystems enable various opportunities for light control through inherent electric and magnetic resonances; however, their full potential has not yet been discovered. Here, emission properties of nitrogen-vacancy (NV) centers in nanodiamonds placed in the near-field zone of silicon nanoresonators are investigated. It is demonstrated experimentally that the spontaneous emission rate of single NV centers in 50 nm nanodiamonds can be modified by their coupling to spherical nanoantennas, reducing the mode of the lifetime distribution by ≈2 times from 16 to 9 ns. It is also shown that the collected intensity of photoluminescence emission from multiple NV centers in a 150 nm nanodiamond coupled to a cylindrical nanoantenna is increased by more than 50% compared to the intensity from the same nanodiamond on a bare substrate.

The development of silicon‐based radiative nanostructures is an important step toward silicon‐based optoelectronic systems. Here an approach for the fabrication of photoluminescent Er‐doped silicon nanoantennas is demonstrated. The combination of electron beam lithography and laser annealing of a thin Er film deposited after fabrication creates an active dielectric nanoantenna operating in the standard telecommunication wavelength range (C‐band). Using the multipole decomposition method the geometrical parameters of the silicon nanoparticle when the first‐order Mie‐resonances are tuned to the erbium emission in C‐band range (transition) is calculated. It is observed experimentally that the presence of the Mie‐resonances provides enhancement of the photoluminescence intensity up to 40% compared to the non‐resonant case. The proposed approach allows for the creation of computational optical chips compatible with existing nanofabrication technologies.

We investigate the optical response of passive (homogeneous) and active (doped by a magnetic-dipole source) silicon nanospheres placed above the gold substrate supporting excitation and propagation of surface plasmon polaritons (SPPs). In the case of the passive system, the influence of the particle electric and magnetic dipole resonances on the channeling of scattered light into the two channels: light-into-light and light-into-SPPs, is studied around the telecommunication wavelength range. Scattering efficiencies of both channels are analytically and numerically calculated and compared for different gaps between the nanosphere and gold substrate. Conditions, under which the resonant distribution of energy between SPPs and light channels can be approximately equal to each other, are revealed. In the case of an active system, associated with a magnetic dipole source embedded in a silicon resonator, two separate emission channels into light and into SPPs are considered as well. The radiation efficiency in each channel as a function of the gap is examined and compared. In particular, it is revealed the conditions when the efficiency of resonant light energy propagation along the two channels is practically equal to each other, and the Purcell factor achieves the value almost two times higher than for the case without the substrate. The obtained results elucidate the features introduced by the Mie dipole resonances of silicon nanospheres to control the light scattering (radiation) and the SPP excitation in dielectric/metal interface systems. The results obtained are perspectives for the development of new compact photonic and plasmonic devices operating at standard telecommunication wavelength ranges.

Development of single photon sources based on color centers in diamond nanoparticles requires a sufficient increase in their brightness. Conventionally, this may be accomplished by coupling of a color center to a high-quality dielectric cavity. Efficient interaction requires a nanodiamond to be placed close to the maximum of the field distribution of the mode of the structure, which can be achieved with a dielectric nanoparticle cavity characterized by a strong electric field inside the gap between the particles. In this work, we calculate the characteristics of such cavity composed of dielectric nanocylinders with realistic geometrical parameters, and investigate the influence of material losses in dielectric on the performance of such system for different color centers. Our results provide a way for designing a dielectric cavity for efficient increase of emission rate of color centers embedded in nanodiamonds.

Recently developed field of all-dielectric nanophotonics allowed for the observation of the Kerker effect, i.e., unidirectional scattering of electromagnetic radiation by a dielectric particle in optical frequency range. In this paper, we consider the analogue of this effect for localized waves which manifests itself as an interference of the evanescent tails of the optical waveguide modes. Specifically, we design a discrete nanophotonic waveguide that supports two degenerate modes characterized by different symmetries with respect to the plane that contains the waveguide axis, leading to an asymmetric field distribution of the propagating wave under appropriate excitation conditions. We perform numerical simulations of the excitation of such a waveguide with a point dipole and predict that its polarization state can be encoded into the field pattern of the signal propagating along the waveguide and transferred for relatively large distances. We also propose a planar directional coupler that consists of a developed discrete waveguide and conventional single-mode dielectric waveguides that exploit the interference effect for routing single photons generated by circularly polarized quantum emitters.

We suggest a novel class of active nanoantennas based on diamond nanoparticles with embedded nitrogen-vacancy centres coupled to Mie resonances of nanoparticles. We theoretically study the optical properties of such nanoantennas including the field enhancement and Purcell effect, and experimentally demonstrate the enhancement of the fluorescence rate of the emitters due to particle resonances, as compared to a nonresonant regime. Our results pave the way towards active dielectric nanophotonics for quantum light sources, bioimaging, and quantum information processing.