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Nanophotonics and in particular Plasmonics has become a very active research field during the past decades. With the development of new advent technologies and control of nanofabrication techniques a deep understanding of the optical of materials at the nanoscale became crucial. We develop theoretical models, and use advanced numerical simulations and modeling, to investigate new optical properties of semiconductor, metallic, and hybrid nanostructures.
We use a large range of methods and HPC for solving Maxwell’s equations. Properties of interest include extinction, scattering, surface- and tip-enhanced Raman scattering, electron energy-loss probability, and second harmonic generation. Numerical approaches such as BEM, DDA, FDTD, FEM, Mie theory, and effective medium theories are used to tackle these problems.
Electron-Based Spectroscopies
Electron-Based Spectroscopies
Electron energy-loss spectroscopy (EELS) and cathodoluminence (CL) are unique tools that are extensively used to investigate the plasmonic response of metallic nanostructures. Novel approaches for EELS and CL calculations using the finite-difference time-domain (FDTD) method have been recently introduced and bench-marked on a large number of systems. These implementations allow to compute EELS and CL spectra for a large variety of geometries, materials, and configurations.
Refs: Cao et al., ACS Photonics, 2015, 2, 369;
Zhang et al., ACS Nano, 2015, 9, 9331; ACS Nano highligh video
Active Plasmonics
Active Plasmonics
Investigation of new concepts such as ultrafast optical switches based on nonlinear plasmonic nanoantennas and plasmonic mode manipulation via plasmon hybridization. In the formaer, antenna nanoswitch operate on the transition from the capacitive to conductive coupling regimes between two closely spaced metal nanorods connected with amorphous silicon. In the later, strong hybridization of nanowire and nanoantennas drives optical mode drifting, pulling, and pushing.
Hybrid Plasmonics
Hybrid Plasmonics
Strong coupling between resonantly matched localized surface plasmons and excitons results in the formation of new hybridized energy states called plexcitons. Similarly, surface plasmons can also couple to acoustic vibrations/phonons sustained by the metallic nanoparticle. Understanding the nature and tunability of these hybrid nanostructures is important for both fundamental studies and the development of new applications. FDTD, BEM, DDA, RUS simulations and effective medium theory allow to investigate the strong plexcitonic coupling (Rabi splitting of 400 meV) and the acousto-plasmonic coupling that are both mediated by the near-field.
Plasmon-Enhanced Spectroscopies
Plasmon-Enhanced Spectroscopies
Metallic nanoparticles with tipped , sharp, and rough surface structures, or exhibiting nanoscale gaps possess highly geometrical-dependent tunable plasmon resonances and intense near-field enhancements exploitable for surface-enhanced Raman spectroscopy (SERS). Understanding of the geometry-dependent plasmonic characteristics and SERS activities of the nanoparticles is possible by use of numerical electrodynamics simulations.
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