Photoluminescence modal splitting strong coupling in hybrid Au/WS/GaP nanoparticle-on-mirror cavities.

By integrating dielectric and metallic components, hybrid nanophotonic devices present promising opportunities for manipulating nanoscale light-matter interactions. Here, we investigate hybrid nanoparticle-on-mirror optical cavities, where semiconductor WS monolayers are positioned between gallium phosphide (GaP) nanoantennas and a gold mirror, thereby establishing extreme confinement of optical fields. Prior to integration of the mirror, we observe an intermediate coupling regime from GaP nanoantennas covered with WS monolayers.

Fluorescence Enhancement in Topologically Optimized Gallium Phosphide All-Dielectric Nanoantennas.

Nanoantennas capable of large fluorescence enhancement with minimal absorption are crucial for future optical technologies from single-photon sources to biosensing. Efficient dielectric nanoantennas have been designed, however, evaluating their performance at the individual emitter level is challenging due to the complexity of combining high-resolution nanofabrication, spectroscopy and nanoscale positioning of the emitter. Here, we study the fluorescence enhancement in infinity-shaped gallium phosphide (GaP) nanoantennas based on a topologically optimized design.

Radiative suppression of exciton-exciton annihilation in a two-dimensional semiconductor.

Two-dimensional (2D) semiconductors possess strongly bound excitons, opening novel opportunities for engineering light-matter interaction at the nanoscale. However, their in-plane confinement leads to large non-radiative exciton-exciton annihilation (EEA) processes, setting a fundamental limit for their photonic applications. In this work, we demonstrate suppression of EEA via enhancement of light-matter interaction in hybrid 2D semiconductor-dielectric nanophotonic platforms, by coupling excitons in WS monolayers with optical Mie resonances in dielectric nanoantennas.

High-Q Nanophotonics over the Full Visible Spectrum Enabled by Hexagonal Boron Nitride Metasurfaces.

All-dielectric optical metasurfaces with high quality (Q) factors have been hampered by the lack of simultaneously lossless and high-refractive-index materials over the full visible spectrum. In fact, the use of low-refractive-index materials is unavoidable for extending the spectral coverage due to the inverse correlation between the bandgap energy (and therefore the optical losses) and the refractive index (n). However, for Mie resonant photonics, smaller refractive indices are associated with reduced Q factors and low mode volume confinement.

Second to fifth harmonic generation in individual β-barium borate nanocrystals.

We have studied the nonlinear optical properties of single β-barium borate nanocrystals, with potential applications as probes in nonlinear sensing and imaging schemes. Our work demonstrates their ability to generate second, third, fourth, and fifth harmonics. The particles' polarization response is studied and compared with simulations based on the bulk nonlinear tensors, with good agreement.