Image-based autofocusing system for nonlinear optical microscopy with broad spectral tuning.

We present an image-based autofocusing system applied in nonlinear microscopy and spectroscopy with a wide range of excitation wavelengths. The core of the developed autofocusing system consists of an adapted two-step procedure maximizing an image score with six different image scorings algorithms implemented to cover different types of focusing scenarios in automated regime for broad wavelength region. The developed approach is combined with an automated multi-axis alignment procedure.

Crystalline heterogeneity in single ferroelectric nanocrystals revealed by polarized nonlinear microscopy.

Ferroelectric nanocrystals have considerable interest for applications in nanophotonics, optical memories and bio-imaging. Their crystalline nature at the nanoscale remains however poorly known, mostly because structural investigation tools on single nanocrystals are lacking. In this work we apply polarization resolved second harmonic generation (P-SHG) imaging on isolated Barium Titanate (BaTiO) nanocrystals to unravel their crystalline nature, exploiting the sensitivity of polarized SHG to local non-centrosymmetry and nanocrystals surface responses.

Reshaping the Second-Order Polar Response of Hybrid Metal-Dielectric Nanodimers.

We combine the field confinement of plasmonics with the flexibility of multiple Mie resonances by bottom-up assembly of hybrid metal-dielectric nanodimers. We investigate the electromagnetic coupling between nanoparticles in heterodimers consisting of gold and barium titanate (BaTiO or BTO) nanoparticles through nonlinear second-harmonic spectroscopy and polarimetry. The overlap of the localized surface plasmon resonant dipole mode of the gold nanoparticle with the dipole and higher-order Mie resonant modes in the BTO nanoparticle lead to the formation of hybridized modes in the visible spectral range.

Tunable 2D binary colloidal alloys for soft nanotemplating.

The realization of non-close-packed nanoscale patterns with multiple feature sizes and length scales via colloidal self-assembly is a highly challenging task. We demonstrate here the creation of a variety of tunable particle arrays by harnessing the sequential self-assembly and deposition of two differently sized microgel particles at the fluid-fluid interface. The two-step process is essential to achieve a library of 2D binary colloidal alloys, which are kinetically inaccessible by direct co-assembly.

Anapoles in Free-Standing III-V Nanodisks Enhancing Second-Harmonic Generation.

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.

Enhanced Second-Harmonic Generation from Sequential Capillarity-Assisted Particle Assembly of Hybrid Nanodimers.

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.