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

研究了铁电和反铁电液晶中近晶层的旋转，采用了多种材料、电池结构和驱动电压波形。在施加具有波形不对称分量的交流电场时，所述近晶层均匀旋转。在含电杂质的体系中，通过施加直流电压使层均匀旋转，这与电流体动力效应有关。从全反射椭偏测量中发现，在电池表面附近的层以与体相同的方式旋转。在一种由向列相直接过渡到近晶C相的近晶液晶中观察到特征畴的形成，该液晶具有平行于摩擦轴的长矩形畴。利用该材料制备了周期性畴结构。利用N^*-SmC^*相序的铁电液晶也实现了激光照射下的可逆光记录。在具有N^*-SmC^*相序的偶氮染料掺杂铁电液晶体系中实现了光致层开关。在紫外光的照射下，偶氮染料在液晶中发生光异构化，相变为N^*相，在绿光的连续照射下，液晶的相又回到SmC^*相。在光的连续照射期间同时施加电场时，层对齐的方向被切换到相反的方向。

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.