%L discovery1479901 %V 28 %J Advanced Materials %N 15 %A S Chen %A F Zeuner %A M Weismann %A B Reineke %A G Li %A VK Valev %A KW Cheah %A NC Panoiu %A T Zentgraf %A S Zhang %X 3D chirality is shown to be unnecessary for introducing strong circular dichroism for harmonic generations. Specifically, near-unity circular dichroism for both second-harmonic generation and third-harmonic generations is demonstrated on suitably designed ultrathin plasmonic metasurfaces with only 2D planar chirality. The study opens up new routes for designing chip-type biosensing platform, which may allow for highly sensitive detection of bio- and chemical molecules with weak chirality. %O Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This is the peer reviewed version of the following article: [Chen, S; Zeuner, F; Weismann, M; Reineke, B; Li, G; Valev, VK; Cheah, KW; (2016) Giant Nonlinear Optical Activity of Achiral Origin in Planar Metasurfaces with Quadratic and Cubic Nonlinearities. Advanced Materials , 28 (15) pp. 2992-2999. 10.1002/adma.201505640], which has been published in final form at http://dx.doi.org/10.1002/adma.201505640. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. %D 2016 %T Giant Nonlinear Optical Activity of Achiral Origin in Planar Metasurfaces with Quadratic and Cubic Nonlinearities %P 2992-2999