High-Efficiency Spiral Zone Plates in Sapphire Lu, Yi-Ming ; Tian, Zhen-Nan ; Yang, Shuang-Ning ; Hua, Jian-Guan ; Liu, Xue-Qing ; Zhao, Yang ; Chen, Qi-Dai ; Zhang, Yong-Lai ; Sun, Hong-Bo Abstract Publication: IEEE Photonics Technology Letters Pub Date: June 2019 DOI: 10.1109/LPT.2019.2913712 Bibcode: 2019IPTL...31..979L