Abstract
Liquid crystal alignment is a crucial step in display manufacture. Photo-alignment of liquid crystal media figures among several non-contact methods under study as potential alternatives to mechanical rubbing of polymer films. Obliquely deposited silica has also been studied as an alignment surface. We report initial studies on a non-contact approach that combines the advantages of both polymers and silica in a photosensitive spin-on type hybrid organic-inorganic glass film. We have discovered a form of nonresonant photo-induced anisotropy (PIA) in these glasses that will align nematic 4-pentyl-4'-cyanobiphenyl (5CB) liquid crystal. Optical self-writing with polarized guided waves in the glasses produces birefringence that can be read out by waveguide Raman scattering. 5CB spontaneously orders on the waveguides and indicates that PIA in the self-written glasses propagates to the surface of the film. PIA with polarized light at 488 nm also orients 5CB in a conventional twist cell fabricated from hybrid glasses derived from acrylates and arenes covalently bound to silicon. Electro-optic measurements on the hybrid glasses yield liquid crystal EO parameters that depend in complex ways on PIA, the chemical composition of the glass and the processing conditions of the films.
Published Version
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