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20 April 1998 Electrically controlled cholesteric gratings
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Electrically controlled diffractive gratings are developed on the basis of cholesteric liquid crystal confined between two transparent electrodes. The electrodes are coated with unidirectionally treated alignment layers. The initial state is planar, with helix axis oriented normally to the electrodes. The applied field causes reorientation of molecules and creates structures modulated in the plane of the cell. Surface alignment provides unidirectional uniformity of the modulation. The parameters of the modulated structures and light diffraction are controlled by the cholesteric pitch, cell thickness and applied voltages. In the device of the first type, the modulated state produces Raman-Nath (RN) diffraction and allows a the modulated structure depends on the applied field. Diffraction regimes of both RN and Bragg types are demonstrated for this geometry. In the RN regime, the electric field allows one to control continuously the deflection angle. This effect can be used in various beam steering devices. The variation in the diffracted beam direction is more than 15 degrees. Typical working voltages are less than 10V. We present both the experimental results and 3D computer simulations of modulated structures caused by the field.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Oleg D. Lavrentovich, Darius Subacius, Sergey V. Shiyanovskii, and Philip J. Bos "Electrically controlled cholesteric gratings", Proc. SPIE 3292, Spatial Light Modulators, (20 April 1998);


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