Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 19: Plasmonics and Nanooptics II

O 19.8: Talk

Monday, March 11, 2013, 17:45–18:00, H31

Chiral Fields in Achiral Systems — •Martin Schäferling, Xinghui Yin, and Harald Giessen — 4th Physics Institut, Research Center SCoPE, and Research Center SimTech, University of Stuttgart, Stuttgart, Germany

Chirality – the absence of mirror symmetry – is an integral component of our world. The so-called optical chirality quantifies the chirality of electromagnetic fields [1]. It has been shown that fields with high optical chirality can arise near plasmonic nanostructures with strong planar or three-dimensional geometrical chirality [2].

We demonstrate numerically that geometrical chirality is not a necessary prerequisite for obtaining chiral near-fields: Even a higly symmetric linear plasmonic rod antenna illuminated with linearly polarized light under normal incidence generates chiral electromagnetic fields [3]. We explain this behavior qualitatively by analyzing a Hertzian dipole driven at resonance. This simple model is further utilized to analyze and compare different incident polarizations. We show that the chiral near-field patterns generated by circularly polarized light are still dominated by the distribution found for the linear polarization.

The handedness of the chiral fields near a square structure can be flipped locally by changing the polarization angle of the incident light. Based on these findings, we propose a novel method for enantiomer sensing using linearly polarized light.

[1] Y. Tang and A. E. Cohen, Science 332, 333 (2011).

[2] M. Schäferling et al., Phys. Rev. X 2, 031010 (2012).

[3] M. Schäferling et al., Opt. Expr. 20, 26326 (2012).