Multilevel phase-type diffractive lens embedded in sapphire Li, Qian-Kun ; Lu, Yi-Ming ; Hua, Jian-Guan ; Yu, Yan-Hao ; Wang, Lei ; Chen, Qi-Dai ; Juodkazis, Saulius ; Sun, Hong-Bo Abstract Publication: Optics Letters Pub Date: October 2017 DOI: 10.1364/OL.42.003832 Bibcode: 2017OptL...42.3832L