Strong Cavity-Optomechanical Transduction of Nanopillar Motion.

Nanomechanical resonators can serve as ultrasensitive, miniaturized force probes. While vertical structures such as nanopillars are ideal for this purpose, transducing their motion is challenging. Pillar-based photonic crystals (PhCs) offer a potential solution by integrating optical transduction within the pillars.

Excitation and detection of acoustic phonons in nanoscale systems.

Phonons play a key role in the physical properties of materials, and have long been a topic of study in physics. While the effects of phonons had historically been considered to be a hindrance, modern research has shown that phonons can be exploited due to their ability to couple to other excitations and consequently affect the thermal, dielectric, and electronic properties of solid state systems, greatly motivating the engineering of phononic structures. Advances in nanofabrication have allowed for structuring and phonon confinement even down to the nanoscale, drastically changing material properties.

Direct Detection of Optical Forces of Magnetic Nature in Dielectric Nanoantennas.

Optical forces on nanostructures are usually characterized by their interaction with the electric field component of the light wave, given that most materials present negligible magnetic response at optical frequencies. This is not the case however of a high-refractive-index dielectric nanoantenna, which has been recently shown to efficiently support both electric and magnetic optical modes. In this work, we use a photoinduced force microscopy configuration to measure optically induced forces produced by a germanium nanoantenna on a surrounding silicon near-field probe.

Acoustic Far-Field Hypersonic Surface Wave Detection with Single Plasmonic Nanoantennas.

The optical properties of small metallic particles allow us to bridge the gap between the myriad of subdiffraction local phenomena and macroscopic optical elements. The optomechanical coupling between mechanical vibrations of Au nanoparticles and their optical response due to collective electronic oscillations leads to the emission and the detection of surface acoustic waves (SAWs) by single metallic nanoantennas. We take two Au nanoparticles, one acting as a source and the other as a receptor of SAWs and, even though these antennas are separated by distances orders of magnitude larger than the characteristic subnanometric displacements of vibrations, we probe the frequency content, wave speed, and amplitude decay of SAWs originating from the damping of coherent mechanical modes of the source.

Photochemistry and Photophysics of Shinorine Dimethyl Ester.

The photostability and photophysical properties of the dimethyl ester of the mycosporine-like amino acid shinorine have been experimentally evaluated in aqueous solution and in the presence of direct micelles prepared with a cationic or an anionic detergent, respectively. In comparison with shinorine, the ester molecule increases the photostability, the fluorescence quantum yield and the fluorescence lifetime in water as well as in the micellar solutions. The effects are more pronounced in sodium dodecyl sulfate solutions and suggest that the electrostatic attractions with the micellar interface contribute to limit the movement of the molecules and influence the relative rate of their deactivation channels.

Tailored Hypersound Generation in Single Plasmonic Nanoantennas.

Ultrashort laser pulses impinging on a plasmonic nanostructure trigger a highly dynamic scenario in the interplay of electronic relaxation with lattice vibrations, which can be experimentally probed via the generation of coherent phonons. In this Letter, we present studies of hypersound generation in the range of a few to tens of gigahertz on single gold plasmonic nanoantennas, which have additionally been subjected to predesigned mechanical constraints via silica bridges. Using these hybrid gold/silica nanoantennas, we demonstrate experimentally and via numerical simulations how mechanical constraints allow control over their vibrational mode spectrum.