PoSHGOAT · Potential-dependent Second-Harmonic Generation in Optical Antennas measured Time-resolved
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2020-09-01 → 2022-02-28
- EU contribution
- €137,605
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Potential-dependent Second-Harmonic Generation in Optical Antennas measured Time-resolved
The project addressed one relevant aspect of nonlinear optical phenomena at the nanoscale, namely the possibility to control second-harmonic generation in metal nanoantennas by electrical bias, i.e. by modulating the amount of surface charges on the nanostructures. Metal nanoantennas are widely used to boost light-matter interactions at the nanoscale because of their ability to sustain localized resonances supported by conduction electrons and, among the many applications, have been successfully applied over the last decade to boost nonlinear processes over regions smaller than the wavelength of the electromagnetic radiation, something that is not possible with conventional optics. Within this framework, the possibility to achieve an external and efficient control of the nonlinear conversion processes by electrical means would pave the road towards electrically-controlled devices that find applications e.g. in optical quantum protocols or sensing. To contribute to this goal, the PoSHGOAT project aimed at demonstrating the experimental feasibility of the concept by achieving modulation of the second harmonic generation (SHG) in electrically-connected antennas. Along this path, advanced nanofabrication techniques, numerical modeling, spectrally- and time-resolved spectroscopies were considered among the main ingredients for the realization and understanding of the modulation phenomena.
Data: CORDIS, © European Union
Project objective
Second-harmonic generation (SHG) is a nonlinear optical effect, with promising applications in background-free spectroscopy, ultrafast optical switching, and optical information processing. What is missing is the integration of these effects at the nanoscale, to be sensitive down to the singe molecule level and competitive in size with silicon electronics.Metallic nanoparticles, called optical antennas (OAs), show resonances in the infrared and optical wavelength regime. They exhibit plasmons, coupled states of photons and electron density waves, which allow concentrating light much better than conventional optics, down to 10 nm³. OAs enable SHG in nanometer-sized volumes, but until now only with low efficiency. This is due to the complex task of: (i) a resonance to receive light with wavelength A, (ii) routing the energy to the OA surface (efficient SHG due to symmetry breaking), (iii) exploiting a second antenna resonance which can gather the SHG at wavelength B=A/2, and finally (iv) emitting the wavelength B to the far field.In the proposed project PoSHGOAT I will control and optimize SHG in OAs. To this aim, I will introduce four novelties to SHG research:(1) Fabrication of electrically-contacted nanoantennas with ultra-fine tips (r = 3 nm) and ultra-narrow gaps (g = 3 nm) by a subsequent Ga-ion and He-ion milling procedure.(2) Modulation of the surface charges in metallic nanoparticles by applying an external potential.(3) Time-resolved pump-probe spectroscopy of SHG with an applied voltage, eventually even with induced tunnelling of electrons in a highly asymmetric antenna gap. This will establish ultrafast control over the OA surface charge density and, thus, SHG.(4) Numerical modelling of SHG and evolutionary optimization of nanoparticle geometries to maximize SHG in optical antennas.All these efforts together will increase our understanding of nonlinear processes in plasmonic resonators, towards novel design rules for nonlinear plasmonic devices.
Original text from CORDIS.
Participants
- POLITECNICO DI MILANO · MilanoCoordinatorItaly
Links
Data: CORDIS, © European Union