Jérémie Béal

Two-Color Single Hybrid Plasmonic Nanoemitters with Real Time Switchable Dominant Emission Wavelength.

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.

Copolymer template control of gold nanoparticle synthesis via thermal annealing

Here we present an original process combining top-down and bottom-up approaches by annealing a thin gold film evaporated onto a hole template made by etching a PS–PMMA copolymer film. Such process allows a better control of the gold nanoparticle size distribution which provides a sharper localized surface plasmon resonance. This makes such route appealing for sensing applications since the figure of merit of the Au nanoparticles obtained after thermal evaporation is more than doubled. Such process could besides allow tuning the localized surface plasmon resonance by using copolymers with various molecular weights and thus be attractive for surface-enhanced Raman spectroscopy.

Single step synthesis and organization of gold colloids assisted by copolymer templates

We report here an original single-step process for the synthesis and self-organization of gold colloids by simply incorporating gold salts into a solution prepared using polystyrene (PS)-polymethylmethacrylate copolymer and thiolated PS with propylene glycol methyl ether acetate as a solvent. The spin-coating and annealing of this solution then allows the formation of PS domains. Depending on the polymer concentration of the as-prepared solution, there can be either one or several gold nanoparticles (Au NPs) per PS domain. For high concentrations of Au NPs in PS domains, the coupling between plasmonic NPs leads to the observation of a second peak in the optical extinction spectrum. Such a collective effect could be relevant for the development of optical strain sensors in the near future.

Strategies for self-organization of Au nanoparticles assisted by copolymer templates

We discuss here different strategies for making arrays of Au nanoparticles using copolymer templates. Top-down and bottom-up routes are considered and the optical properties of as-prepared Au nanoparticles are discussed and compared to numerical simulations. Potential for applications such as biosensors or strain sensors is also assessed.

Enhanced gold film-coupled graphene-based plasmonic nanosensor

In this work, a trilayer graphene is used as a thin non dielectric spacer with a high index of refraction, between Au film and Au NPs. Encouraged by the sharpness of the localized surface plasmon resonance LSPR induced by this system, we performed sensitivity measurements to refractive index change in the surrounding medium of the sensor. The presence of graphene led to both higher sensitivity and sharper full width at half maximum FWHM and thus higher figure of merit FOM (2.8) compared to the system without graphene (2.1).