title: Switchable Fresnel lens based on micropatterned alignment.
abstract: In this Letter we disclose a method to fabricate a liquid crystal (LC) Fresnel zone lens (FZL) with higher efficiency. The LCFZL, based on alternate twisted nematic (TN) and planar aligned (PA) regions, has been prepared by means of a two-step photo-alignment process. The FZL profile for both optical regimes, i.e., in TN and PA alignment domains, generates the same focal length (f). Thus, the proposed LCFZL manifests double light intensity at the focal point and therefore offers double the efficiency of existing FZLs. Moreover, because of lower driving voltage and fast response, these elements could find application in many modern devices.
authors.affiliation: Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Xiao-Qian
authors.initials: XQ
authors.lastname: Wang
authors.forename: Abhishek K
authors.initials: AK
authors.lastname: Srivastava
authors.forename: Vladimir G
authors.initials: VG
authors.lastname: Chigrinov
authors.forename: Hoi-Sing
authors.initials: HS
authors.lastname: Kwok