Zhang Ranran, Zhao Qiuling, Wang Xia, Li Jensen, Tam Wing Yim
Optoelectronic Materials and Technologies Engineering Laboratory, Shandong, Physics Department, QingDao University of Science and Technology, Shandong 266061, China.
Department of Physics, William Mong Institute of Nano Science and Technology, and Center for Metamaterial Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Nano Lett. 2020 Apr 8;20(4):2681-2687. doi: 10.1021/acs.nanolett.0c00311. Epub 2020 Mar 27.
Circular phase-dichroism (CPD) has been suggested for the characterization of chiral metasurfaces in supplementing the conventional circular dichroism (CD). Conventional CD probes the bulk properties while the CPD, reported recently in 2D chiral metasurfaces using an air-gap Fabry-Perot setup, is based on the surface properties. Here we propose and demonstrate a robust birefringent interference approach to obtain the CPD by replacing the air-gap with a uniaxial birefringent material in which interference is realized by the difference in the refractive indexes for the ordinary and extraordinary components of the material. We measure the transmission phases of metasurfaces fabricated on birefringent sapphire substrates and obtain clear CPDs for chiral metasurfaces but vanishing for achiral metasurfaces. Importantly, our approach can be applied to metasurfaces fabricated on nonbirefringent substrates by add-on birefringent materials. We confirm our results by a Jones matrix method using data obtained from full-wave simulations, and good agreements with experiments are obtained.
圆二色性（CPD）已被建议用于表征手性超表面，作为传统圆二色性（CD）的补充。传统CD探测的是体性质，而最近在二维手性超表面中利用气隙法布里 - 珀罗装置报道的CPD则基于表面性质。在此，我们提出并演示了一种稳健的双折射干涉方法，通过用单轴双折射材料取代气隙来获得CPD，其中干涉是由材料寻常分量和非寻常分量的折射率差异实现的。我们测量了在双折射蓝宝石衬底上制备的超表面的透射相位，获得了手性超表面清晰的CPD，而非手性超表面的CPD则为零。重要的是，我们的方法可通过附加双折射材料应用于在非双折射衬底上制备的超表面。我们使用从全波模拟获得的数据，通过琼斯矩阵方法证实了我们的结果，并与实验取得了良好的一致性。
