Random PhoXonic Surface – RANDOM

- Numerical simulation, time domain (FDTD, Finite Difference Time Domain) and frequency domain (FE, Finite Element) techniques.
- Mathematical approach controlled using statistical laws.
- Fabrication of the random surfaces we will take benefit of the IEMN cleanroom facilities
- optical far field and near field characterizations
- hyperspectral high resolved microscopy techniques

les WPs ont avancé conformément au diagramme de Gantt défini dans le projet. Cette période a permis une mise en place des études optiques, acoustiques et optomécaniques et les premiers résultats sont en cours d’analyse. Du point de vue concept, le désordre a été introduit mathématiquement (partenaire LPP) et la notion d’hyperuniformité versus périodicité et RANdom est apparue comme une démonstration élémentaire à mettre en évidence et à relier à des propriétés physiques (optique, acoustiques). Ce type de désordre, lié à la notion d’écart type sur les positions des résonateurs, représente un lien entre les WPs et sera commun à l’ensemble des partenaires. Du point de vue numérique, les codes numériques par éléments finis montrent leurs limites temporelles et de mémoire dans les calculs de réponses spectrales des surfaces RANdom de plus de 200 résonateurs. Pour dépasser cette difficulté, des codes de calcul analytiques ont été développés par le partenaire iemn/ephoni. Le choix des matériaux a été fait pour répondre au mieux aux exigences expérimentales acoustiques et optiques tout en conservant les objectifs. En optique (ICB), la géométrie reste des particules métalliques sur un substrat diélectrique et un plan de masse métallique (Au). Pour l’acoustique (INSP), les premières études sont faites à partir de piliers d’Al déposées sur un substrat d’Al. Les paramètres géométriques ont été étudiés par simulation (IEMN Dome, IEMN Ephoni) et la fabrication des premiers échantillons a été réalisée.

The first samples will be characterized in optic and acoustic, separately. The concordence with the simulation will be done.
Three scenaries will be adressed in the following months from a mathematical definition of the hyperuniformity.
3 scenari will be take as an issue: characterize the level of disorder from periodic , hyperuniform and random.

• Surface Acoustic Waves-Localized Plasmon Interaction in Pillared Phononic Crystals, A. Noual, R. Akiki, Y. Pennec, E. H. El Boudouti, and B. Djafari-Rouhani, Phys. Rev. Applied 13, 024077 2020
• Saturable Metasurfaces for Laser Mode Locking J. Wang, A. Coillet, O. Demichel, Z. Wang, D. Rego, A. Bouhelier, P. Grelu & B. Cluzel, Light: Sciences & Applications 9, 50 (2020)
• Akiki, R., Pennec, Y., Noual, A., Lheurette, E., Bonello, B., Djafari Rouhani, B. 2021, Evanescent Coupling between Aluminum Pillars, The fifteenth International Congress on Artificial Materials for Novel Wave Phenomena, New York, 20-25 September.

The project RANDOM proposes to set a mathematically controlled disorder in a system of dual electromagnetic and acoustic resonators on a surface (i) to discover new photonic and phononic physical behaviors in relation with a random distribution controlled by mathematical rules (order/disorder transition, hyperuniformity, percolation paths, Anderson type localization), (ii) to co-localize photons and phonons on randomly distributed sites and to enhance their optomechanical interaction, (iii) to develop a time resolved pump-probe acousto-optic near-field microscope for phoXonic experiments and (iv) to propose an OM component operating at the telecom wavelength consisting in an acoustic, optical and OM stamping of the phoXonic surface. RANDOM will allow producing a complex coding of a random patterns with numerous degrees of freedom usable in information coding.

The typical platform under investigation in the RANDOM project is composed of disordered resonators, made of gold nano-pillars to confine both the EM and the elastic waves. We propose to investigate in this dual phononic/photonic (phoXonic) platform the effect of disorder, and more especially of different mathematical probability laws governing the particle geometrical distributions, on transport phenomena, nanoscale localization, and enhanced OM interactions. Numerically, time and frequency domain techniques will be used to perform calculations of the dispersion curves, transmission, reflection, and absorption spectra, field distributions, density of states and eigenvalues of the metasurface. The involvement of mathematical skills in probability and statistics, as Poisson or Gibbs processes, appears in the distribution of the resonators. The microscopic distribution of the acoustic and EM fields in the structure will be also investigated and analyzed experimentally, based on transient grating and picosecond ultrasonic (elastic side), high-resolved optical microscopy and FTIR spectroscopy (EM side). Finally, all results will be used to deliver an OM component, named OM-QR code, consisting in an OM image of the random distribution. The principle lays on the optical reading (the response) of a mechanical wave (the message) through the OM coupling. Finally, we will demonstrate the properties of a new OM component, called OM-QR code, based on the optical reading (the response) of a mechanical wave (the message) via OM coupling. With such functionality, we will be able to define an uncoded image of the random distribution.

As such, the project RANDOM goes beyond the current state of the art regarding (i) fundamental theoretical and experimental OM studies of phononic, photonic, and phoXonic crystals, (ii) instrumental development with realization of a time resolved pump-probe acousto-optics microscope, and (iii) applied science with the demonstration of a new OM component for information coding. To succeed, the project brings together a multidisciplinary consortium of four complementary partners in the fields of acoustics, optics and mathematics. With the working wavelength of this new experimental platform at 1.55 µm, corresponding to GHz phonons and photons around 180 THz, RANDOM offers new research and applications perspectives in the field of information and communication.