Rotatable liquid crystal waveplate
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A photoresist well of size 60 × 60 × 15 μm3 has been used to confine a droplet of nematic liquid crystal to create a rotatable waveplate. The optical texture of the droplet between crossed polarisers is consistent with the nematic n-director running substantially along a diameter of the droplet and connecting two nematic defects on the curved edges of the droplet. Electric field induced azimuthal rotation of the axis of the nematic liquid crystal droplet has been demonstrated. At higher temperatures, 30 °C and above, the droplet is more circular in shape and can be switched to arbitrary rotation angles. At lower temperatures, 25 °C and below, the sides of the droplet are straightened by the interaction with the well walls and the switching tends to favour discrete orientations of the optic axis. The shape of the time–voltage switching response curve for rotation by an angle of 40° also depends on the temperature of the droplet. A switching time that is inversely proportional to the voltage squared results when the droplet is nearest to circular in shape.
KeywordsNematic Liquid Crystal S1813 Layer Polarisation Mode Dispersion Optical Texture Nematic Droplet
The authors gratefully acknowledge Drs. Newton, Roach, Shirtcliffe and Tsakonas at Nottingham Trent University for advice on device fabrication issues. GW gratefully acknowledges Kodak European Research Ltd. for funding.
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