Extrinsic chirality of non-concentric plasmonic nanorings

We show how extrinsic chirality, i.e. the optical activity of achiral media exhibited at oblique light incidence, can be achieved in plasmonic nanorings by symmetry breaking. We demonstrate that even a small, 5% offset of an inner hole of a 190 nm gold ring results in a measurable circular dichroism signal in the near-infrared region. By using computer simulations, we show that optical activity arises upon excitation of a symmetric dipolar localized surface plasmon resonance mode due to the appearance of co-aligned electric and magnetic dipole moments. © 2017 Optical Society of America OCIS codes: (250.5403) Plasmonics; (160.4236 ) Nanomaterials. References and links 1. W. Lenz, “Malformations caused by drugs in pregnancy,” Am. J. Dis. Child. 112, 99–106 (1966). 2. E. Hendry, T. Carpy, J. Johnston, M. Popland, R. V. Mikhaylovskiy, A. J. Lapthorn, S. M. Kelly, L. D. Barron, N. Gadegaard, and M. 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