0000000000204286
AUTHOR
Renaud Bachelot
Optical Properties of hybridized arrays of subwavelength holes in a metallic film
International audience
Quantitative analysis of localized surface plasmons based on molecular probing
International audience; We report on the quantitative characterization of the plasmonic optical near-field of a single silver nanoparticle. Our approach relies on nanoscale molecular molding of the confined electromagnetic field by photoactivated molecules. We were able to directly image the dipolar profile of the near-field distribution with a resolution better than 10 nm and to quantify the near-field depth and its enhancement factor. A single nanoparticle spectral signature was also assessed. This quantitative characterization constitutes a prerequisite for developing nanophotonic applications.
Apertureless scanning near-field optical microscopy: a comparison between homodyne and heterodyne approaches
International audience; In coherent homodyne apertureless scanning near-field optical microscopy (ASNOM) the background field cannot be fully suppressed because of the interference between the different collected fields, making the images difficult to interpret. We show that implementing the heterodyne version of ASNOM allows one to overcome this issue. We present a comparison between homodyne and heterodyne ASNOM through near-field analysis of gold nanowells, integrated waveguides, and a single evanescent wave generated by total internal reflection. The heterodyne approach allows for the control of the interferometric effect with the background light. In particular, the undesirable backgro…
Error signal artifact in apertureless scanning near-fiel microcospy
International audience
Nanophotopolymerization Triggered by the Enhanced Optical Near Field of Metallic Nanoparticles
International audience; A novel approach is reported for imaging and quantifying both the depth and the strength of the optical near-field, of a single colloidal metal nanoparticle, associated with localized surface plasmons. It will be emphasized that this technique relies on a nanoscale molecular molding of the confined electromagnetic field of metal colloids, irradiated at their resonance, by a photo-activated polymer, which enabled us to directly image the dipolar profile of the near-field distribution with an unprecedented resolution, better than 10 nm. Moreover, the approach used enabled one to quantify the near-field enhancement factor. This approach has overcome all the difficulties…
Two-Color Single Hybrid Plasmonic Nanoemitters with Real Time Switchable Dominant Emission Wavelength
International audience; We demonstrate two-color nanoemitters that enable the selection of the dominant emitting wavelength by varying the polarization of excitation light. The nanoemitters were fabricated via surface plasmon-triggered two-photon polymerization. By using two polymerizable solutions with different quantum dots, emitters of different colors can be positioned selectively in different orientations in the close vicinity of the metal nanoparticles. The dominant emission wavelength of the metal/polymer anisotropic hybrid nanoemitter thus can be selected by altering the incident polarization.
Electromagnetic Singularities and Resonances in Near-Field Optical Probes
Over the last two decades scanning near-field optical microscopy (SNOM) has demonstrated its ability to provide optical resolution significantly better than the diffraction limit (<20 nm). The general principle of SNOM relies on the approach of a nanometer-sized object in the optical near-field of a sample to be studied. This nano-object (NO) is usually the extremity of a probe. Regardless of the nature of the observed SNOM signal (inelastic scattering, fluorescence, etc.), the detection of the light is achieved in the far-field regime where the NO acts as a mediator between the optical near-field and the detector. Figure 1 is a schematic illustration of the SNOM principle.
Tuning of an Optical Dimer Nanoantenna by Electrically Controlling Its Load Impedance
International audience; Optical antennas are elementary units used to direct optical radiation to the nanoscale. Here we demonstrate an active control over individual antenna performances by an external electrical trigger. We find that by an in-plane command of an anisotropic load medium, the electromagnetic interaction between individual elements constituting an optical antenna can be controlled, resulting in a strong polarization and tuning response. An active command of the antenna is a prerequisite for directing light wave through the utilization of such a device.
Plasmon-based free-radical photopolymerization : effect of diffusion on nanolithography processes
This Article interrogates the mechanisms responsible for nanoscale photopolymerization induced by confined and enhanced electromagnetic fields. Surface plasmon dipolar resonance of individual Ag nanoparticles was used as an optical near-field source to locally trigger the reaction of a photopolymerizable formulation. Laser excitation of the nanoparticles embedded in the formulation reproducibly generates polymer features with typical dimensions ranging from 2 nm to a few tens of nanometer. We have determined the physicochemical parameters and mechanisms controlling the spatial extent of the photopolymerization process. We found that the diffusion of the dye is the main process limiting the …
Off-Resonant Optical Excitation of Gold Nanorods: Nanoscale Imprint of Polarization Surface Charge Distribution
International audience; We report on the nanoscale optical characterization of gold nanorods irradiated out of their plasmonic resonance. Our approach is based on the reticulation of a photopolymerizable formulation locally triggered by enhanced electromagnetic fields. The tiny local field enhancement stems from the surface polarization charges associated with the electric field discontinuity at the metal/dielectric interface. This allows us to get a nanoscale signature of the spatial distribution of the surface charge density in metallic nanoparticles irradiated off-resonance.
Two-color nanoemiter
International audience
Two-color plasmonic hybrid nano-emitters: a new paradigm in hybrid plasmonics?
International audience
Reversible Strong Coupling in Silver Nanoparticle Arrays Using Photochromic Molecules
International audience; In this Letter, we demonstrate a reversible strong coupling regime between a dipolar surface plasmon resonance and a molecular excited state. This reversible state is experimentally observed on silver nanoparticle arrays embedded in a polymer film containing photochromic molecules. Extinction measurements reveal a clear Rabi splitting of 294 meV, corresponding to ∼13% of the molecular transition energy. We derived an analytical model to confirm our observations, and we emphasize the importance of spectrally matching the polymer absorption with the plasmonic resonance to observe coupled states. Finally, the reversibility of this coupling is illustrated by cycling the …
Two-color hybrid nano-emitters
International audience