title: Twisted nematic liquid crystal polarization grating with the handedness conservation of a circularly polarized state.
abstract: We propose a liquid crystal (LC) polarization grating that conserves the polarization state of incident light, wherein the variation range of the twist angle is 2π. The design scheme for theoretically 100% diffraction efficiency of the first-diffraction order is derived, and a prototype LC grating is evaluated. Under zero voltage, the fabricated LC grating exhibits high efficiency of the first-order diffraction, validating the proposed design scheme. The high efficiency of the second-order diffraction can also be achieved under a high voltage so that the LC director in the midplane is vertical to the substrate plane. The circular polarization sense of the second-order diffraction is identical to that of the incident light as in the case of the first-order diffraction. This grating functions as a beam deflector, steering the input beam in three different directions (zeroth-, first-, and second-order diffractions) by adjusting the applied voltage.
authors.affiliation: Department of Electronics and Information Systems, Faculty of Systems Science and Technology, Akita Prefectural University, 84-4 Tsuchiya-Aza-Ebinokuchi, Yurihonjo, Akita 015-0055, Japan. mhonma@akita-pu.ac.jp
authors.forename: Michinori
authors.initials: M
authors.lastname: Honma
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nose