Department of Physics
Nonlinear processes are often governed by selection rules imposed by the symmetries of the molecular configurations. The most well-known examples include the role of centrosymmetry breaking for the generation of even harmonics, and the selection rule related to the rotational symmetry in harmonic generation for fundamental beams with circular polarizations. While the role of centrosymmetry breaking in second harmonic generation has been extensively studied in plasmonic systems, the investigation of selection rules pertaining to circular polarization states of harmonic generation is limited to crystals, i.e., symmetries at the atomic level. In this Letter we demonstrate the rotational symmetry dependent third harmonic generation from nonlinear plasmonic metacrystals. We show that the selection rule can be imposed by the rotational symmetry of metacrystals embedded into an isotropic organic nonlinear thin film. The results presented here may open new avenues for designing symmetry-dependent nonlinear optical responses with tailored plasmonic nanostructures.
Physical Review Letters
American Physical Society
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This work was partly supported by EPSRC (EP/J018473/1) and NSFC (Grant No. 61328503). T. Z. and S. Z. acknowledge ﬁnancial support by the European Commission under the Marie Curie Career Integration Program. F. Z. and T. Z. acknowledge financial support by the DFG Priority Program SPP1391. K. W. C. and E. Y. B. P. acknowledge support from the Research Grant Council of Hong Kong under Projects No. HKUST2/CRF/11G and No. AoE/P-02/12. G. L. thanks Donal Donat Conor Bradley for fruitful discussions on nonlinear optical materials. S. C., G. L., and F. Z. contributed equally to this work.
Link to Publisher’s Edition
© 2014 American Physical Society
Chen, Shumei, Guixin Li, Franziska Zeuner, Wing Han Wong, Edwin Yue Bun Pun, Thomas Zentgraf, Kok Wai Cheah, and Shuang Zhang. "Symmetry-selective third-harmonic generation from plasmonic metacrystals." Physical Review Letters 113.3 (2014): 033901-1-033901-5.
Additional FilesJA-4861-25571_suppl_publisher.pdf (164 kB)
In the supplementary mateial, we compare the intensities of THG between metacrystals with and without PFO, and a uniform PFO film. The comparison confirms that the nonlinear signal is generated in the PFO film, whereas the gold nanorods mainly contribute to the field enhancement.