Photonic-plasmonic linear and non-linear coupling

Glass is transparent. Metals are shiny. A piece of wood is opaque. Each material has a different relationship with light. Some materials let light go through; others reflect back; others absorb it. This is true also at the nanoscale. In addition, optical properties at the nanoscale are even more interesting. Imagine if your gold ring would change its color if you break it in half, or if you change its size anyhow. In fact, this is what happens for nano-sized metals and semiconductors. In particular, metals can act as an antenna for light. Gold nanopads have the ability to redirect light in specific directions and locations. Semiconductors change their response to light depending on its size and shape. What about coupling the two systems?

Within this research field, I investigated the optical properties of new semiconductor architectures (V-shaped membranes). Fabrication of these structures is very challenging and we did it in collaboration with Prof. Fontcuberta group at EPFL. I studied the their optical properties, analyzing the change in the scattering spectra as the size is changed. I used second harmonic generation to probe the non-linear properties of such nanostructures, finding very interesting correlation between structural properties and optical behavior.

Second harmonic excitation spectroscopy is a very powerful too to investigate material properties. I used it to characterize substoichiometric silicon nitride thin films, to elucidate size-dependent effects on gold nanoparticles, and to obtain polarization-controlled multispectral nanofocusing of metal nanoantennas.

Moreover, I investigated the coupling between photonic and plasmonic properties. In collaboration with EPFL, we designed gold nanoantenna arrays coupled with gallium arsenide nanowires. By using second harmonic excitation spectroscopy, we elucidated all the coupling effects in these systems and we showed that new modes emerge at expenses of the expected structural resonances.

These projects have been funded by the Air Force Office of Scientific Research, and performed during my experience at Boston University.

Publication output

Conference proceedings

  • Integration of metallic nanostructures on nanowires for modification of their optical properties
    A. Casadei, E. Alarcon-Llado, E. F. Pecora, J. Trevino, C. Forestiere, D. Ruffer, E. Russo-Averchi, F. Matteini, G. Tutuncuoglu, M. Heiss, L. Dal Negro, A. Fontcuberta i Morral
    Frontiers in Nanophotonics, CSF Conference 2015
  • Second harmonic excitation spectroscopy in studies of Fano-type coupling in plasmonic arrays
    G. F. Walsh, J. Tervino, E. F. Pecora, L. Dal Negro
    SPIE Optics + Photonics 2015
  • Engineering light coupling in single nanowire with metal nano-antennas
    A. Casadei, J. Trevino, E. F. Pecora, E. Alarcò- Lladò, D. Ruffer, E. Russo-Averchi, G. Tutuncuoglu, F. Matteini, C. Forestiere, L. Dal Negro, A. Fontcuberta i Morral
    International Conference on One dimensional Nanomaterials ICON 2013
  • Second-harmonic generation from plasmonic nanoantennas and arrays
    A. Capretti, C. Forestiere, E. F. Pecora, G. Walsh, J. Trevino, S. Minissale, L. Dal Negro, G. Miano
    The International Conference on Surface Plasmon Photonics SPP6
  • Second-harmonic generation in substoichiometric silicon nitride layers
    E. F. Pecora, A. Capretti, G. Miano, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, V1.00119