Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 54: Nano-Optics (Single Quantum Emitters and Plasmonics)

Q 54.8: Talk

Thursday, March 8, 2018, 12:15–12:30, K 0.023

Nonlinear 3D chiral plasmonics — •Lili Gui, Mario Hentschel, and Harald Giessen — 4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70569 Stuttgart, Germany

Optical activity is a general phenomenon in nature, as many biomolecules are chiral. Chiral plasmonics is highly interesting for biosensing applications since natural chiral substances can be mimicked and a gigantic chiroptical response can be obtained due to the superchiral near-field. Exploration of nonlinear chiroptical effects in chiral plasmonic nanostructures is even more desired since the nonlinear chiroptical effects might be orders of magnitude higher than their linear counterparts. Although diverse chiral plasmonic systems have been investigated, the underlying physical mechanism for nonlinear plasmonic chirality is far from being understood and further quantitative modelling is particularly missing.

Here we study the third-order chiroptical response of 3D chiral structures consisting of identical corner-stacked gold nanorods, the so-called plasmonic Born-Kuhn analog. We experimentally investigate the third-harmonic spectroscopy with both left- and right-handed fundamental light. Utilizing a coupled anharmonic oscillator model that includes phase retardation of the incoming fundamental and outgoing generated wave, we are able to retrieve the third-order chiroptical effects. This model is quite instructive for the efficient design of plasmonic chiral structures for giant nonlinear circular dichroism and might pave the way towards ultrasensitive nonlinear chiral sensing.