Ilya Razdolski, Yiguo Chen, Alexander J. Giles, Sandy Gewinner, Wieland Schöllkopf, Minghui Hong, Martin Wolf, Vincenzo Giannini, Joshua D. Caldwell, Stefan A. Maier, and Alexander Paarmann:
Nano Lett. 16 (11), 6954-6959 (2016), pp 6;
[ DOI: 10.1021/acs.nanolett.6b03014 ];
arXiv:1607.05158 [physics.optics] (2016), pp. 11;
DOI: arXiv:1607.05158 [physics.optics];
We report on strong enhancement of mid-infrared second harmonic generation (SHG) from SiC nanopillars due to the resonant excitation of localized surface phonon-polaritons within the Reststrahlen band. The magnitude of the SHG peak at the monopole mode experiences a strong dependence on the resonant frequency beyond that described by the field localization degree and the dispersion of linear and nonlinear-optical SiC properties. Comparing the results for the identical nanostructures made of 4H and 6H SiC polytypes, we demonstrate the interplay of localized surface phonon polaritons with zone-folded weak phonon modes of the anisotropic crystal. Tuning the monopole mode in and out of the region where the zone-folded phonon is excited in 6H-SiC, we observe a prominent increase of the already monopole-enhanced SHG output when the two modes are coupled. Envisioning this interplay as one of the showcase features of mid-infrared nonlinear nanophononics, we discuss its prospects for the effective engineering of nonlinear-optical materials with desired properties in the infrared spectral range.
The original publication is available by link DOI: 10.1021/acs.nanolett.6b03014