Hybrid Anisotropic Plasmon-Photonics for Light Emission – HAPPLE

Hybrid plasmonics relies on radiative and non radiative coupling between Metal Nano Particles (MNP) and other (often organic) materials. It is at the origin of recent development of active plasmonics and “Spasers” (Surface Plasmons Amplification by Stimulated Emission of Radiation). Hybrid nanosystems are generally fabricated from isotropic coating of MNP using a homogeneous optically active dielectric material. Such isotropy prevents the selection of any specific emission mode of the hybrid particle using the incident light polarization. The HAPPLE project aims at developing an original approach for the realization of new light-emitting hybrid metal/polymer nano-systems (LEHPS) presenting organic active medium having an anisotropic spatial distribution. As a result, modes and optical properties of LEPHS can be selectively activated with the polarization state of the incident light. LEHPS fabrication is based on a near-field photopolymerization process triggered by plasmon-enhanced fields produced by the MNP itself. The result is a MNP exhibiting a polymeric coating reproducing the excited optical near-field intensity distribution. HAPPLE will benefit from the know-how issued from a former successful ANR project (Photohybrid) during which plasmon-based nano-photopolymerization was validated. HAPPLE aims to take a new step forwards by developing new fluorescent photopolymers for the realization of LEHPS nanosystems with controllable emission (intensity, wavelength, emission diagram,..). The 4-year long project involves 4 interdependent workpackages (WP). WP1 is dedicated to fabrication and plasmonic study of the MNP that will be selected. WP2, which will benefit from recent successful preliminary experiments, will focus on the development and optimization of fluorescent doped photopolymers formulations. These formulations will include both photosensitizers enabling adjustable spectral sensitivity and fluorophores selected for their high solubility and photochemical stability. LEPHS fabrication with increasing complexity will be performed within WP3. WP4 is dedicated to the detailed characterization and understanding of the LEHPS photophysical properties. HAPPLE gathers 4 partners of complementary expertise: LNIO, Université de Technologie de Troyes (plasmonics, near-field optics, nanoscale light source/polymer interaction), IS2M, University of Haute Alsace (chemistry of photopolymers), LEPO, CEA-DSM (Saclay) (optics of nano-objects, plasmons/fluorophore coupling, photophysics of organized molecular systems) and CEA-LFP (MNP chemical synthesis and fluorescence of Chromophores). The 1st year will be centered on the study of LEHPS based on the dipolar resonance of spherical MNP. Year 2 will work to the realization of doubly functionalized MNP using the 2 different dipolar resonances of metallic nanorods. We will mainly focus our attention onto polarization-dependent fluorescence (spectroscopy, fluorescence decay profiles obtained with pulsed excitation..), this dependence resulting from the anisotropic nature of the hybrid system.
More complex MNP will be tested (big spheres, cubes, triangles..) during Year 3, towards the exploitation of plasmon quadrupolar modes. Year 4 will be devoted to the use of coupled MNPs or MNPs presenting geometric singularities such as nanostars. Finally, in a search for possible Plasmon-mediated stimulated emission processes, the above studies will be complemented by analyses of the dependence on excitation intensity of both the quantum efficiency and the dynamics of the photo-luminescence. If successful, the demonstration of the possibility of a stimulated emission (that was the object of a patent between 2 HAPPLE partners) and its characterization will constitute a breakthrough which is expected to give birth to a new class of plasmonic nano-lasers with unprecedented properties i.e. of controllable modal emission properties using incident light polarization, opening thus new domains of applications.