Enhancement Mechanisms of the Second Harmonic Generation from Double Resonant Aluminum Nanostructures

• DOI: 10.1021/acsphotonics.7b00288
• Publication Date: 2017-05-08T18:12:51Z
• Authors: Kuang-Yu Yang; Jérémy Butet; Chen Yan; Gabriel D. Bernas...; Olivier J. F. Martin
• Keywords: 0103 physical sciences; 01 natural sciences

Multiresonant plasmonic nanoantennas have recently gained a lot of attention due to their ability to enhance nonlinear optical processes at the nanoscale. The first nanostructure designed for this purpose was an aluminum antenna composed of three arms, designed to be resonant at both the fundamental and the second harmonic frequencies. It was demonstrated that second harmonic generation induced by its resonances at both the fundamental and second harmonic wavelengths is higher than the one from a simple dipolar nanoantenna supporting a resonance at the fundamental wavelength only. However, the underlying mechanisms leading to this strong nonlinear signal are still unclear. In this study, both advanced simulations and experiments are combined to investigate in details the role of the mode coupling in the enhancement of second harmonic generation. By varying the length of the nanoantenna arms, it is clearly demonstrated that second harmonic generation is enhanced when the coupling between the quadrupole and...