Chiral Metalens of Circular Polarization Dichroism with Helical Surface Arrays in Mid-Infrared Region
Chiral Metalens of Circular Polarization Dichroism with Helical Surface Arrays in Mid-Infrared Region
复制标题
中红外区螺旋面阵列圆偏振二色性手性超透镜
DOI：
10.1002/adom.201901129
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发表时间：
2019-12-17
影响因子：
9
通讯作者：
Wang, Chinhua
中科院分区：
文献类型：
--
作者：
He, Cun;Sun, Ti;Wang, Chinhua
本文从理论和实验两方面证明了在3-5 μ m的中红外波段，一束圆偏振光（左旋或右旋）透射聚焦于设计焦距，而另一束被反射的圆偏振二向色性（CPD）手征超透镜。超透镜由覆盖有金薄膜的亚波长螺旋表面阵列组成，金薄膜产生具有金属螺旋表面的旋向性的CPD，而聚焦是利用相位分布来实现的，该相位分布被发现由每个单独的螺旋表面沿着透镜的径向方向的旋转角度来确定。设计了一种工作在3-5 μ m波段的手性圆二色超透镜（CMCD），并采用三维激光直写技术和电子束蒸发技术制备了这种超透镜。利用锁相热成像技术成功地实现了圆偏振光的聚焦，消除了3-5 μ m波段的强背景红外辐射，实验结果与理论模拟一致。该器件为用单一元件实现成像和圆二色性的综合功能提供了新的思路。
A chiral metalens of circular polarization dichroism (CPD) in the mid-infrared region of 3-5 mu m is demonstrated both theoretically and experimentally, in which one of the circularly polarized light beams (either left-handed or right-handed) is transmissively focused at a designed focal length, while the other beam is reflected. The metalens consists of subwavelength helical surface arrays covered by a gold thin film that gives rise to CPD with the handedness of the metallic helical surface, while the focusing is realized with a phase distribution that is found to be determined by the rotation angle of each individual helical surface along the radial direction of the lens. A chiral metalens of circular dichroism (CMCD) operating in the 3-5 mu m region is designed and experimentally fabricated by the 3D laser direct writing technique followed by electron beam evaporation. Experimental focusing of the circularly polarized lights is demonstrated successfully with the lock-in thermography technique to eliminate the severe background infrared radiation in the 3-5 mu m wavelength region, and it is found that the results are consistent with the theoretical simulation. The demonstrated CMCD provides a new idea of implementing integrated functions of both imaging and circular dichroism with a single element.