Layr Rotation Dynamics and Its Functional Application in Ferroelectric and Antiferroelectric Liquid Crystal Devices

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The smectic layer rotation in ferroelectric and antiferroelectric liquid crystals has been studied using a variety of materials, cell configurations and waveforms of driving voltage. The smectic layer uniformly rotates upon the application of ac electric field having an asymmetric component of the waveform. In the system including electrical impurity, the layer rotates even by applying dc voltage, which is associated with the electrohydrodynamic effect. From the total reflection ellipsometry measurement, it has been found that the layers in the vicinity of the cell surfaces rotate in the same manner as that in bulk.The characteristic domain formation has been observed in a smectic liquid crystal having direct phase transition from the nematic to the smectic C phases, which has long rectangular domains parallel to the rubbing axis. Using this material, periodical domain structure has been fabricated. Reversible optical recording by the irradiation of laser light has also been realized using ferroelectric liquid crystal with N^*-SmC^* phase sequence.Photo-induced layer switching has been realized in the system of azo-dye doped ferroelectric liquid crystal having N^*-SmC^* phase sequence. Upon the irradiation of the UV light, photoisomerization of azo-dye in the liquid crystal takes place and the phase changes into the N^* phase, and upon the sequential irradiation of the green light, the phase of the liquid crystal go back to the SmC^* phase. Upon the simultaneous application of the electric field during this sequential irradiation of the light, the direction of the layer alignment is switched to the opposite direction.