title: Switchable broadband achromatic half-wave plate with nematic liquid crystals.
abstract: We describe a broadband achromatic half-wave retarder for normally incident light of arbitrary polarization. The device consists of a stack of one nematic liquid-crystal cell with uniform alignment sandwiched between two twisted nematic layers that have identical twist angles (135 degrees) but different orientations of their surface alignment. As a specific application, for light with linear polarization at 45 degrees to the optic axis of the homogeneous cell the stack functions efficiently as an optical switch. The switch rotates the incident linear polarization by 90 degrees in the absence of an electric field. When sufficiently high voltage is applied to all three layers, the device produces a near-zero effect on the incident polarization. An achromatic response in the spectral range 400-700 nm is achieved for both activated and quiescent states.
authors.affiliation: Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA. marina@lci.kent.edu
authors.forename: M D
authors.initials: MD
authors.lastname: Lavrentovich
authors.forename: T A
authors.initials: TA
authors.lastname: Sergan
authors.forename: J R
authors.initials: JR
authors.lastname: Kelly