Plasmon-enhanced second harmonic sensing

Lavinia Ghirardini; Anne-Laure Baudrion; Marco Monticelli; Daniela Petti; Paolo Biagioni; Lamberto Duò; Giovanni Pellegrini; Pierre-Michel Adam; Marco Finazzi; Michele Celebrano

arXiv · 1711.05584

Plasmon-enhanced second harmonic sensing

Lavinia Ghirardini·Anne-Laure Baudrion·Marco Monticelli·Daniela Petti·Paolo Biagioni·Lamberto Duò·Giovanni Pellegrini·Pierre-Michel Adam·Marco Finazzi·Michele Celebrano

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Abstract

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 (FOM = $(ΔI/I)/Δn$) that accounts for the relative change in the measured intensity, \textit{I}, against the variation of the environmental refractive index \textit{n}. While the signal-to-noise ratio achieved in both regimes allows the detection of a minimum refractive index variation $Δn_{min} \approx 10^{-3}$, 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.

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Lavinia Ghirardini, Anne-Laure Baudrion, Marco Monticelli, Daniela Petti, Paolo Biagioni, Lamberto Duò, Giovanni Pellegrini, Pierre-Michel Adam, Marco Finazzi, Michele Celebrano. 2017-11-15. Plasmon-enhanced second harmonic sensing. https://arxiv.org/abs/1711.05584

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