Dynamic phase assembled terahertz metalens for reversible conversion between linear polarization and arbitrary circular polarization

• 作者: Jitao Li Guocui Wang Zhen Yue Jingyu Liu Jie Li Chenglong Zheng Yating Zhang Yan Zhang Jianquan Yao
• 来源期刊: 光电进展（英文版）
• 年，卷（期）: 2022,（1）
• 所属期刊栏目: Original Article
• 页码范围: 24-34
• 页数: 11页
• 语种: 英文
• DOI: 10.29026/oea.2022.210062

摘要

If a metalens integrates the circular polarization (CP) conversion function, the focusing lens together with circular-polariz-ing lens (CPL) in traditional cameras may be replaced by a metalens. However, in terahertz (THz) band, the reported metalenses still do not obtain the perfect and strict single-handed CP, because they were constructed via Pancharatnam-Berry phase so that CP conversion contained both left-handed CP (LCP) and right-handed CP (RCP) components. In this paper, a silicon based THz metalens is constructed using dynamic phase to obtain single-handed CP conversion. Also, we can rotate the whole metalens at a certain angle to control the conversion of multi-polarization states, which can simply manipulate the focusing for incident linear polarization (LP) THz wave in three polarization conversion states, in-cluding LP without conversion, LCP and RCP. Moreover, the polarization conversion behavior is reversible, that is, the THz metalens can convert not only the LP into arbitrary single-handed CP, but also the LCP and RCP into two perpen-dicular LP, respectively. The metalens is expected to be used in advanced THz camera, as a great candidate for tradi-tional CPL and focusing lens group, and also shows potential application in polarization imaging with discriminating LCP and RCP.