Chirality, tailored by external morphology and internal composition, has been realized by controlled curved-lattice epitaxial growth of In(x)Al(1-x)N nanospirals. The curved morphology of the spiral segments is a result of a lateral compositional gradient while maintaining a preferred crystallographic growth direction, implying a lateral gradient in optical properties. Individual nanospirals show an asymmetric core-shell structure with curved basal planes. Mueller matrix spectroscopic ellipsometry shows that the tailored chirality is manifested in the polarization state of light reflected off the nanospirals.

Tunable liquid crystal light deflecting devices based on nonuniform anchoring energy are proposed. These devices have uniform thicknesses of the layers they are composed of, and beam deviation is controlled with a uniform electrical field. Potential applicability of such an approach in beam deflectors and active lenses is investigated. It is shown that the approach is a competitive alternative to liquid crystal light deflecting devices, in which the needed spatial distribution of liquid crystal molecules is achieved either due to nonuniform thickness or due to generation of nonuniform electrical field.

Original Publication: Sergiy Valyukh, Iryna Valyukh, V Chigrinov, H S Kwok and Hans Arwin, Liquid crystal light deflecting devices based on nonuniform anchoring, 2010, APPLIED PHYSICS LETTERS, (97), 23, 231120. http://dx.doi.org/10.1063/1.3526311 Copyright: American Institute of Physics http://www.aip.org/

The study of a tunable liquid crystal lens having a uniform cell gap, uniform applied voltage and non‐uniform anchoring energy was done. Optimal parameters of such a lens were found and discussed. We demonstrated that producing a desired director gradient profile with non‐uniform spatial distribution of the anchoring energy is a good alternative for other known methods applied for liquid crystal lenses.

In this paper we discuss a new dynamic drive scheme for bistable reflective cholesteric liquid crystal displays with high multiplexing level. Only two voltage levels (U and 0) are used for the addressing in this drive scheme. Addressing speed is about the time of the fast transition of a cholesteric liquid crystal from the homeotropic state to the transient planar state per line. The maximum value of using voltage is slightly overtop the critical voltage of a cholesteric-nematic transition. These facts make this drive scheme very perspective in application for such kind of displays.

Among the important features of holographic displays are the wide viewing angles and the full color of the reconstructed images. The present work focuses on achievement of both features. We propose an increased-viewing-angle full-color holographic display using two tiled phase-only spatial light modulators (SLMs), a 4f concave mirrors system, and a temporal-spatial multiplexing method. The 4f optical system consists of two concave mirrors and serves to increase the viewing angle. A temporal-spatial multiplexing synchronization control (TSMSC) method is developed to achieve a full-color image and to remove the color crosstalk of the image. We calculate RGB phase-only holograms of a computer-generated color pyramid by using a slice-based Fresnel diffraction algorithm. The experimental results indicate that the proposed display system is feasible to reconstruct a full-color holographic 3D image with a viewing angle of 12.8°, which is about 3.8 times wider than the viewing angle formed by a single SLM.

Formation of a desired liquid crystal (LC) director distribution by the use of inhomogeneous anchoring and pre-tilt angle for electrically controlled diffractive optical elements (DOE) is studied. Such LC DOE can have high periodicity and diffraction efficiency. At the same time they are free of constructive regularities, e.g. a periodic arrangement of the electrodes or thickness deviations, which have undesired impact on diffractive characteristics of LC DOE of other types. We focus on evaluation of potential functional abilities of LC DOE with inhomogeneous alignment. The reasons causing restriction of the LC DOE diffraction efficiency and periodicity are considered. Approaches for improvement of characteristics of the LC DOE are discussed. ©2012 Optical Society of America

This is an author produced version of a paper published in Thin Solid Films. This paper has been peer-reviewed but does not include the final publisher proofcorrections or journal pagination. AbstractThin films of Ni x W 1-x oxides with x = 0.05, 0.19, 0.43 and 0.90 were studied. Films with thicknesses in the range 125 -250 nm were deposited on silicon wafers at room temperature by reactive DC magnetron co-sputtering from targets of Ni and W. The films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopic ellipsometry (SE). XRD spectra and SEM micrographs showed that all films were amorphous and possessed a columnar structure. The ellipsometric angles Ψ and Δ of as-deposited films were measured by a rotating analyzer ellipsometer in the UV-visible-near infrared range (0.63-6.18 eV) and by an infrared Fourier transform rotating compensator ellipsometer in the 500-5200 cm -1 wavenumber range. SE measurements were performed at angles of incidence of from 50° to 70°. Parametric models were used to extract thicknesses of the thin films and overlayers of Ni x W 1-x oxide at different compositions, band gaps and optical constants. Features in the optical spectra of the Ni x W 1-x oxides were compared with previous data on tungsten oxide, nickel oxide and nickel tungstate.

We introduce a method for the determination of the optical retardation, its wavelength dispersion, the cell twist angle, and the orientation of the input director in a reflective liquid crystal (LC) cell. These parameters are found from the extremes of a characteristic function defined as a sum of two spectral reflectivities of the LC cell placed between a pair of linear polarizers. The reflectivities are measured for two cell orientations, one of which is arbitrary and the other one is turned through 45°. Both theoretical analysis and experimental procedures are presented. Excellent agreement between the experiment and our theory has been found. The proposed method can be applied to the measurement of reflective LC cells with small and large cell gaps, as well as cells with small and large twist angles.