Achiral banana-shaped molecules have recently aroused much intention in academia because they can exhibit ferroelectricity or antiferroelectricity in spite of the achirality of the molecules. Using differential thermal analysis, polarizing optical microscopy and two-beam coupling techniques, we have investigated the effect of photo-irradiation on the electro-optical properties of a banana-shaped liquid crystal that contains azo-linkages in its two legs of the molecules. In the presence of an electric field (in the range of 5-20 MV/m), the polarization of the liquid crystal evolves with the duration of the photo-irradiation. Our results have demonstrated that the electro-optical properties of this azo banana-shaped liquid crystal can be controlled by external photons. The photo-induced trans-cis isomerization of the azo-linkages is suggested be responsible for the changes both in the structures of the polarization current curves and in the magnitude of polarization of the azo banana-shaped liquid crystal.
© 2005 Optical Society of AmericaPDF Article