title: Nematic liquid-crystal polarization gratings by modification of surface alignment.
abstract: The stylus of an atomic force microscope is used to scribe preferred directions for liquid-crystal alignment on a polyimide-coated substrate. The opposing substrate that comprises the liquid-crystal cell is rubbed unidirectionally, resulting in a twisted nematic structure associated with each micrometer-sized pixel. The polarization of light entering from the uniformly rubbed substrate rotates with the nematic director by a different amount in each pixel, and each of the two emerging polarization eigenmodes interferes separately. Two examples are discussed: a square grating that allows only odd-order diffraction peaks and a grating that combines rotation with optical retardation to simulate a blazed grating for circularly polarized light. The gratings can be electrically switched if used with semitransparent electrodes.
authors.affiliation: Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, USA.
authors.forename: Bing
authors.initials: B
authors.lastname: Wen
authors.forename: Rolfe G
authors.initials: RG
authors.lastname: Petschek
authors.forename: Charles
authors.initials: C
authors.lastname: Rosenblatt