DESCRIPTION :
In the last decade metasurfaces (MSs), i.e. 2D arrays of optical nanoantennas with subwavelength size and separation [1] have revolutionized the field of linear optics with the promise to replace bulky and difficult-to-align optical components with ultrathin and flat devices like metagratings, metalenses (MLs) and metaholograms, which can also implement new functionalities in terms of aberrations correction and arbitrary wavefront shaping.
The field of flat optics also showed its potential in the nonlinear regime [2] mostly with the huge of III-V semiconductors in two spectral ranges: mid-infrared based on the resonant of quantum-well inter sub band transitions and short wavelength infrared (SWIR) (based on non-resonant structures). In the latter domain, to date, the most studied phenomenon has been second harmonic generation (SHG), which has proven very useful to assess the potential of nonlinear metasurfaces (NLMSs) for nonlinear conversion. However, sum frequency generation (SFG) looks much more promising to go beyond academic interest and develop potentially useful optoelectronic devices. The main reason for it is that the two SFG inputs can have different powers and wavelengths.
Therefore: (a) a weak signal can be mixed with a strong pump and, as a result, one can increase the frequency conversion efficiency by increasing the pump intensity up to signal depletion or radiation damage; (b) the independent tuning of signal and pump wavelengths enables significant spectral agility.
Principales activités
The main goal of the present postdoctoral position is to model, design, and optimize an efficient and ultra- compact upconverter of SWIR radiation into the silicon absorption band. We start first with the two-steps modelling design in which the modeling involves three linear simulations in the frequency domain: one for the pump and signal inputs, and another for the generated nonlinear field, with the latter arising from the overlap of the nonlinear polarization and the nonlinear field distribution. In most of the cases the two-step approach is sufficient to provide a qualitative response of the nonlinear interaction. However, in circumstances where the time dynamics comes into play and/or there is broad spectrum excitation, two-step approaches are no longer appropriate, and one must simulate the full nonlinearity inside Maxwell's equations, which could be computationally costly. An alternative approach is to couple the linear Maxwell's equations to nonlinear
ordinary differential equations describing the physical mechanism of the problem.
We will rely on our advanced numerical methodology introduced to design highly efficient NLMS. The first component of this methodology is a general modelling approach for the numerical characterization of metasurfaces by solving the full system of 3D time-domain Maxwell equations, which is referred to as the Discontinuous Galerkin Time-Domain (DGTD) method. This DGTD full-wave solver is implemented in the DIOGENeS software suite, which has been developed at INRIA since 2015 [3]. The second component of our modelling methodology is a numerical optimization method. We will rely on the Efficient Global Optimization (EGO) method, an adaptive statistical learning approach based on Gaussian Process (GP) models. The numerical methodology developed at INRIA has been used to optimize various linear metasurface configurations [4-7].
References
1. W. Chen et al., Flat optics with dispersion-engineered metasurfaces, Nature Review Material, vol. 5, 604 (2020)
2. C. De Angelis, G. Leo, D. Neshev, Nonlinear Meta-Optics, CRC Press - Taylor & Francis (2020)
3. DIOGENeS: A DG-based software suite for nano-optics https://diogenes.inria.fr/
4. Isnard et al., Advancing Wavefront Shaping with Resonant Nonlocal Metasurfaces: Beyond the Limitations of Lookup Tables, Scientific Reports 14, 1555 (2024).
5. Elsawy et al., Multiobjective statistical learning optimization of RGB metalens, ACS Photonics, vol. 8, 2498 (2021)
6. Elsawy, et al., Optimization of metasurfaces under geometrical uncertainty using statistical learning, Optics Express, vol. 29, 29887 (2021).
7. Elsawy et al., Universal Active Metasurfaces for Ultimate Wavefront Molding by Manipulating the Reflection Singularities, Laser Photonics Review, vol. 17, 2200880 (2023)
Code d'emploi : Chargé de Recherches (h/f)
Domaine professionnel actuel : Scientifiques
Niveau de formation : Bac+8
Temps partiel / Temps plein : Plein temps
Type de contrat : Contrat à durée indéterminée (CDI)
Compétences : Suite Logicielle, Programmation Informatique, Fortran (Programming Language), Python (Langage de Programmation), Table de Consultation, OpenMP, Informatique Scientifique, Conception et Développement de Logiciel, Anglais, Agilité, Sens de la Communication, Esprit d'Équipe, Motivation Personnelle, Écoute Active, Génie Electrique, Mathématiques Appliquées, Physique Appliquée, Optique et Lunetterie, Dispersion (Optique), Électromagnétisme, Equations, Méthodes par Éléments Finis, Domaine Fréquentiel, Travaux d'Usinage Laser, Optimisation Mathématique, Équations Différentielles Ordinaires (CALCUL Différentiel), Équation Différentielle Partielle, Recherche Post-Doctorale, Pompes, Technologie Infrarouge
Courriel :
Stephane.Lanteri@inria.fr
Téléphone :
0139635511
Type d'annonceur : Employeur direct
