Ferroelectric Liquid Crystal Over Silicon Spatial Light Modulators - Principles, Practice and Prospects

Source: CiteSeer

ABSTRACT The hybrid technology which combines a thin layer of ferroelectric liquid crystal directly on top of a CMOS backplane has provided a hybrid technology for spatial light modulators which has already reached a mature stage of development. Devices of around 10 6 pixels are under construction. The use of devices in a number of systems has already been demonstrated. Key words spatial light modulators head-up displays optical data processing liquid crystal devices 1 Introduction A spatial light modulator (SLM) is a device capable of impressing information onto an optical wavefront. SLMs exist in many forms [1]. Light modulation may be carried out by electro-optic, acousto-optic and mechanical effects, among others. A SLM may be addressed optically, acoustically, electrically, electronically or by electron beam. The applications of such devices are manifold and include information display, coherent optical data processing, data routing and holography. The overall field of SLMs has been...

  • [Show abstract] [Hide abstract]
    ABSTRACT: Surface stabilisation of ferroelectric liquid crystals (SSFLC) shows interesting properties: in plane switching, high viewing angle and fast response. Liquid crystal on silicon (LCOS) devices have an active matrix fabricated onto a silicon buffer, which requires metallization of the inner surface to achieve reflectivity. In this work, the influence of the cell thickness on the device colour upon switching has been studied. Little variations of the cell thickness without damaging surface stabilisation change phase delays, selecting the reflected wavelength if the birefringence is unchanged. Light path is double than that in a transmissive cell, thus similar thickness variations cause higher colour deviations.
    Molecular Crystals and Liquid Crystals 01/2004; 410(1):457-465. DOI:10.1080/15421400490433505 · 0.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Poincaré sphere representation is used to analyze the polarization transformation achieved with a ferroelectric liquid crystal (FLC) optical modulator. This device acts as a switchable wave-plate, in which the orientation of the principal axes rotates under the action of an applied bipolar voltage. In the standard operational mode for intensity switching, the rotation angle of the principal axes is θ = π/4 and the phase shift is φ = π (half-wave-plate). However, for wavelengths different from the design one, the FLC deviates from the half-wave-plate performance and the optical contrast is diminished. We use the Poincaré sphere representation to perform a theoretical analysis of the intensity switch performance of the FLC modulator as a function of the phase shift φ. Using spherical trigonometric relations we derive analytical expressions for the intensity contrast as a function of φ and we show how to compensate its decrease when φ = π by using appropriate elliptically polarized illumination. These situations are experimentally demonstrated using a commercially available FLC cell.
    Journal of Optics A Pure and Applied Optics 01/2009; 11(1):15507-9. DOI:10.1088/1464-4258/11/1/015507 · 1.92 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The flatness of silicon backplanes for ferroelectric liquid crystal microdisplays is essential for their commercial success. The various factors affecting the flatness of liquid crystal on silicon backplanes are reviewed. A flattening technique is proposed based on a promising method that employs induced stress of thin films to control the deformation of silicon wafer. Limitations of this technique are discussed.
    Displays 06/2002; 23(3):115-119. DOI:10.1016/S0141-9382(02)00017-3 · 1.21 Impact Factor