Lai Pengtao, Dong Guohua, Wang Wei, Chen Tao, Lv Tingting, Lv Bo, Zhu Zheng, Li Yuxiang, Guan Chunying, Shi Jinhui
Opt Express. 2020 May 11;28(10):15071-15080. doi: 10.1364/OE.390055.
Intrinsic and extrinsic chiral responses have been widely investigated in metamaterials, however the relationship between them has been seldom discussed. We numerically and experimentally demonstrate angle enhanced chiral dichroism and study the separation between intrinsic and extrinsic chiral responses in metamaterial with asymmetrically split aperture dimers. The metamaterial exhibits triple-band resonant circular dichroism at normal incidence. The oblique incidence leads to giant enhancement of circular dichroism at two low-frequency resonances while yields an obvious resonance split of the circular dichroism in the vicinity of the high-frequency resonance. The whole circular dichroism response results from the balance between intrinsic and extrinsic chirality and the circular dichroism spectra at positive and negative angles of incidence exhibit an asymmetry due to the existence of intrinsic chirality. Importantly, the intrinsic chirality in the metamaterial may be individually investigated since extrinsic chiral response may be removed from the total circular dichroism by superimposing two circular dichroism spectra at positive and negative incident angles. The metamaterial will be promising to achieve enhanced chiral response and also separately utilize intrinsic and extrinsic chirality for manipulating the polarization state of light.
本征和非本征手性响应已在超材料中得到广泛研究，然而它们之间的关系却很少被讨论。我们通过数值模拟和实验证明了角度增强的手性二向色性，并研究了具有不对称分裂孔径二聚体的超材料中本征和非本征手性响应之间的分离。该超材料在正入射时表现出三波段共振圆二色性。斜入射导致两个低频共振处的圆二色性大幅增强，同时在高频共振附近产生明显的圆二色性共振分裂。整个圆二色性响应源于本征和非本征手性之间的平衡，并且由于本征手性的存在，正负入射角下的圆二色性光谱呈现不对称性。重要的是，超材料中的本征手性可以单独研究，因为通过叠加正负入射角下的两个圆二色性光谱，可以从总圆二色性中去除非本征手性响应。这种超材料有望实现增强的手性响应，并且还能分别利用本征和非本征手性来操纵光的偏振态。
