Plasmon-Enhanced Second Harmonic Sensing

Lavinia Ghirardini (1) , Anne-Laure Baudrion (2) , Marco Monticelli (1) , Daniela Petti (1) , Paolo Biagioni (1) , Lamberto Duò (1) , Giovanni Pellegrini (1) , Pierre-Michel Adam (2) , Marco Finazzi (1) , Michele Celebrano (1)

1 INFM-Dipartimento di Fisica-Politecnico di Milano
2 LNIO - Laboratoire de Nanotechnologie et d'Instrumentation Optique

It has been recently suggested that the nonlinear optical processes in plasmonic nanoantennas allow for a substantial boost in the sensitivity of plasmonic sensing platforms. Here, we present a sensing device based on an array of non-centrosymmetric plasmonic nanoantennas featuring enhanced second harmonic generation (SHG) integrated in a microfluidic chip. We evaluate its sensitivity both in the linear and nonlinear regime using a figure of merit that accounts for the relative change in the measured intensity, I, against the variation of the environmental refractive index n. While the signal-to-noise ratio achieved in both regimes allows attaining a resolution (i.e., minimum detectable refractive index variation) Δnmin ≈ 10–3, the platform operation in the nonlinear regime features a sensitivity (i.e., the FOM) that is at least 3 times higher than the linear one. Thanks to the surface sensitivity of plasmon-enhanced SHG, our results show that the development of such SHG sensing platforms with sensitivity performances exceeding those of their linear counterparts is within reach.

Keywords: Nonlinear optics; Plasmonics; Optical properties; Quantum mechanics; Resonance structures

Domains: Optics / Photonic

Lavinia Ghirardini, Anne-Laure Baudrion, Marco Monticelli, Daniela Petti, Paolo Biagioni, et al.. Plasmon-Enhanced Second Harmonic Sensing. Journal of Physical Chemistry C, 2018, 122 (21), pp.11475-11481. ⟨10.1021/acs.jpcc.8b03148⟩. ⟨hal-02370068⟩