Abstract
We investigate the polarization properties of a two-dimensional (2D) array of metallic elliptical nanoholes in the visible wavelength region. The calculated spectra reveal that such a nonchiral structure exhibits a circular dichroism. The proposed structure is a 2D anisotropic system that possesses two principle polarization directions, which gives rise to different polarization modes along long and short diameters of an elliptical nanohole. When the nonchiral elliptical hole forms a chiral arrangement with the off-normal incident wave vector, the two different polarization modes introduce a net polar vector that forms a chiral triad. Therefore, circular dichroism can be observed in a nonchiral elliptical nanohole array.
Acknowledgments
We acknowledge the financial support from National Natural Science Foundation of China (Grant Nos. 61172059 and 61071123), PhD Programs Foundation of Ministry of Education of China (Grant No. 20110041120015), Postdoctoral Gathering Project of Liaoning Province (Grant No. 2011921008), and the Fundamental Research for the Central University (Grant No. DUT12JB01).