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Abstract
The effects of an azo dye on the diffraction efficiency, morphology and electro‐optic properties of the transmission mode of a holographic polymer dispersed liquid crystal (LC) have been studied. The azo dye induced an induction period which otherwise does not exist, followed by a gradual increase of the diffraction efficiency to a saturation value which increased with increasing azo dye content, as a result of the azo dye reorientating LC molecules within the droplet. The increased diffraction efficiency was caused by the decreased droplet coalescence which was due to the hindered migration of the LC by the dye molecules, and to LC orientation induced by azo dye molecules giving a high refractive index contrast. The droplet size decreased with increasing dye content. The dye also lowered the threshold voltage due to the high dielectric anisotropy caused by the presence of a strong on‐axis dipole moment and decreased the response time.
Acknowledgements
This work was supported by a grant‐in‐aid for the National Core Research Center Program of the Ministry of Science & Technology and the Korea Science & Engineering Foundation (No. R15‐2006‐022‐01002‐0).