Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: a lack of energy losses and invisibility to the propagating electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, in which a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range. We show a novel approach to creating nanoantennas by slicing III-V nanowires into standing disks using focused ion-beam milling. We experimentally demonstrate the suppression of the far-field radiation and the associated strong enhancement of the second-harmonic generation from the disk nanoantennas. With a theoretical analysis of the electromagnetic field distribution using multipole expansions in both spherical and Cartesian coordinates, we confirm that the demonstrated nonradiating configurations are anapoles. We expect that the presented procedure of designing and producing disk nanoantennas from nanowires becomes one of the standard approaches to fabricating controlled chains of standing nanodisks with different designs and configurations. These chains can be essential building blocks for new types of lasers and sensors with low power consumption.

We show enhanced second-harmonic generation (SHG) from a hybrid metal-dielectric nanodimer consisting of an inorganic perovskite nanoparticle of barium titanate (BaTiO) coupled to a metallic gold (Au) nanoparticle. BaTiO-Au nanodimers of 100 nm/80 nm sizes are fabricated by sequential capillarity-assisted particle assembly. The BaTiO nanoparticle has a noncentrosymmetric crystalline structure and generates bulk SHG. We use the localized surface plasmon resonance of the gold nanoparticle to enhance the SHG from the BaTiO nanoparticle. We experimentally measure the nonlinear signal from assembled nanodimers and demonstrate an up to 15-fold enhancement compared to a single BaTiO nanoparticle. We further perform numerical simulations of the linear and SHG spectra of the BaTiO-Au nanodimer and show that the gold nanoparticle acts as a nanoantenna at the SHG wavelength.

Many dielectric and semiconductor materials used for all-dielectric resonators or metasurfaces have low absorption in the near infrared to visible range, but they are lossy in the near ultraviolet (NUV) range due to their low energy band gap. Contrary to this, the ferroelectric lithium niobate (LiNbO3, LNO) has an energy band gap larger than 4 eV, and consequently, very low losses in the NUV range down to 310 nm. Here, we propose LNO nanocubes as a new alternative material for nonlinear photonics in the NUV range. We report that LNO nanocubes fabricated by solvothermal synthesis with sizes from 200 to 300 nm demonstrate strong second harmonic generation (SHG) emission below 400 nm due to Mie resonances, with an SHG enhancement of 10 7 compared to bulk LNO at 360 nm. The LNO nanocubes presented in this work are novel efficient all-dielectric Mie resonant nanostructures for the NUV with a wide range of possible photonic applications, from nanophotolithography to metasurfaces and complex assemblies of nanostructures or nanooptical modulators. The development of photonics was marked by the invention of the laser and the subsequent demonstration of nonlinear optical phenomena, such as sum-and difference-frequency generation, third harmonic generation or optical parametric generation. These nonlinear phenomena are utilized in many applications from optical communication and optical parametric amplification to the development of multiphoton microscopy. 1

International audienceIn this work, we report the auto-assembly experiments of micrometer sized particles by optical trapping in the evanescent field of a photonic crystal nanocavity. The nanocavity is inserted inside an optofluidic cell designed to enable the real time control of the nanoresonator transmittance as well as the real time visualization of the particles motion in the vicinity of the nanocavity. It is demonstrated that the optical trap above the cavity enables the assembly of multiple particles in respect of different stable conformations