Publications by authors named "Philippe Roelli"
Article Synopsis
- Vibrational Raman scattering involves energy exchange between light and molecular vibrations, notably described in quantum terms where both are quantized.
- When these vibrations occur within a plasmonic nanocavity, as seen in surface-enhanced Raman scattering (SERS), the setup acts as an optomechanical cavity that enhances light-vibration interactions, leading to potential advancements in vibrational state manipulation and nonlinear optics at the nanoscale.
- This Perspective aims to bridge the concepts of molecular cavity optomechanics (McOM) and traditional methods, summarizing current progress and challenges while emphasizing parameters crucial for enhancing light-matter interactions in the context of SERS and nanoplasmonics.
Nanocavities formed by ultrathin metallic gaps permit the reproducible engineering and enhancement of light-matter interaction, with mode volumes reaching the smallest values allowed by quantum mechanics. While the enhanced vacuum field in metallic nanogaps has been firmly evidenced, fewer experimental reports have examined the far-field to near-field input coupling under strongly focused laser beam. Here, we experimentally demonstrate selective excitation of nanocavity modes controlled by the polarization and frequency of the laser beam.
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- The Molecular Vibration Explorer is a free online database that allows users to explore vibrational spectra and light-vibration coupling strengths of thiolated molecules.
- The "Gold" version includes data on 2800 thiol compounds linked to gold, while the "Thiol" version focuses on 1900 unbound thiolated compounds, providing detailed spectroscopic parameters for each.
- Users can customize their searches and visualizations, such as checking for large Raman cross-sections or sum-frequency generation efficiencies, and the tool is demonstrated using examples in surface-enhanced spectroscopy.
Coherent upconversion of terahertz and mid-infrared signals into visible light opens new horizons for spectroscopy, imaging, and sensing but represents a challenge for conventional nonlinear optics. Here, we used a plasmonic nanocavity hosting a few hundred molecules to demonstrate optomechanical transduction of submicrowatt continuous-wave signals from the mid-infrared (32 terahertz) onto the visible domain at ambient conditions. The incoming field resonantly drives a collective molecular vibration, which imprints a coherent modulation on a visible pump laser and results in upconverted Raman sidebands with subnatural linewidth.
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- Plasmonic nanojunctions are tiny metal structures with nanometre gaps that enhance light-matter interactions and focus electromagnetic fields at a nanoscale level.
- The study reveals that there are unexpected fluctuations in light emission from excited gold nanojunctions, linked to the formation of internal structures and interactions within the metal.
- Interestingly, these changes do not affect the Raman signal or scattering spectrum, suggesting that metal luminescence can be used to study atomic fluctuations in plasmonic cavities alongside traditional methods.
Monolayer transition-metal dichalcogenides with direct bandgaps are emerging candidates for optoelectronic devices, such as photodetectors, light-emitting diodes, and electro-optic modulators. Here we report a low-loss integrated platform incorporating molybdenum ditelluride monolayers with silicon nitride photonic microresonators. We achieve microresonator quality factors >3 × 10 in the telecommunication O- to E-bands.
View Article and Find Full Text PDFThe exceptional enhancement of Raman scattering by localized plasmonic resonances in the near field of metallic nanoparticles, surfaces or tips (SERS, TERS) has enabled spectroscopic fingerprinting down to the single molecule level. The conventional explanation attributes the enhancement to the subwavelength confinement of the electromagnetic field near nanoantennas. Here, we introduce a new model that also accounts for the dynamical nature of the plasmon-molecule interaction.
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