Photovoltaic Light Valve Induced in a Vertically Aligned Nematic Liquid Crystal on an X-cut Fe:LiNbO3 Substrate (Postprint)
Journal Article - Open Access
Paderborn University Paderborn Germany
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Photovoltaic fields induced in x-cut Fe-doped lithium niobate FeLiNbO3 were used to achieve optically induced defect formation and light valving in a vertically aligned nematic liquid crystal. Initially, the optical axis of the LC was vertically aligned parallel to the surface-normal of the planar, photovoltaic substrates throughout the whole sample. Samples were exposed with a focused continuous wave laser beam and investigated via microscopic imaging in-between crossed polarizers. The optical axis of the planar, x-cut FeLiNbO3 substrates was in the substrate plane and oriented parallel to one of the polarizers, which resulted in an initially dark state. Optically induced surface fields with high in-plane components generated within the substrates led to director reorientations and defect formation. Accordingly, the samples were locally switched in a transmissive state. The area affected by exposure was larger 300 m than the FWHM of the Gaussian exposure beam 14 m. Switching from dark to bright states light valving could be achieved in the investigated samples much more efficiently than in previously investigated samples with z-cut FeLiNbO3-substrates.
- Electrooptical and Optoelectronic Devices