Experimental developments

Since 2014 I have devoted a significant effort to build a unique setup, serving to investigate various physics (SHG, SFG, SPDC, pump-probe, etc…) onto the same single nanostructure simply by flipping mirrors. Chromatic aberrations are automatically compensated by sets of motorized telescopes. The contribution of the dark noise from the single photon counting modules (SPCM) has been reduced below 1 count/s by synchronizing the detection with the pulsed laser source. The latter is composed of a Ti:Sa oscillator pumping an OPO, covering a spectral range from 350 nm to 2.5 µm. The setup is fully computer-controlled for multiple scan capability (for example scanning the spectrometers and the laser simultaneously). I have further developed tracking algorithms to maintain the particle in the focus point with nanoscale resolution. Finally, the photon correlation module with four SPCMs (for future Bell inequality test experiments) is operational, in addition to the near-field manipulator (N. Chauvet and M. Ethis de Corny PhD students).

Modeling developments

Since I started at the Néel Institute, I have significantly enlarged the capabilities of my pioneering finite element modeling of SHG in noble metal nanoparticles. It is now possible to take into account the focusing and collection by high NA microscope objectives, the presence of immersion oil and substrates, as well as to consider any beam profile. In view of the very demanding computations, I have deployed the simulations on a cluster recently acquired at Néel Institute. This has reduced the computation time by a factor of 50, allowing parameterized investigations as a function of wavelength, polarization, particle shape, etc. (G. Laurent, PhD student, is now working full-time on it).