Nonlinear optics with resonant nanostructures.

Zilli A., Carletti L., Di Francescantonio A., Rocco D., Locatelli A., Wu X., Fagiani L., Moia F., Vinel V., Borne A., Feichtner T., Biagioni P., Duò L., Neshev D.N., Hecht B., Bollani M., Toma A., Leo G., Finazzi M., De Angelis C., Celebrano M.
  Lunedì 12/09   14:00 - 19:00   Aula D - Marianna Ciccone   II - Fisica della materia   Presentazione
The ability to harness nonlinear optical processes at the nanoscale would enable the integration of functionalities such as frequency conversion and generation of entangled photon pairs in compact devices. However, the intrinsically perturbative character of these processes often brings about very low efficiencies when they occur in nanometric volumes. To make up for this drawback, one can tailor and exploit the electromagnetic resonances of nanostructures to concentrate light well below the diffraction limit, thereby enhancing light-matter interaction. In our contribution, we will survey various strategies successfully deployed over the last few years by our research group with our international collaborators to boost nonlinear interactions in nanostructured systems, such as single nanoparticles and planar nanoparticle arrays called metasurfaces. We investigated several nonlinear optical processes, including harmonic generation and coherently controlled frequency mixing, with a rich phenomenology ruled by the resonant behavior. We will highlight the opportunities offered by different material platforms (dielectric $vs.$ plasmonic) and the key role played by the breaking of inversion symmetry.