We explore the mechanisms of voltage-induced textural switching and the corresponding electro-optical responses of a binary cholesteric liquid crystal (CLC) composed of the rod-like nematic LC E7 with positive dielectric anisotropy and the bent-core LC dimer CB7CB with large flexoelectric coefficients. Our results indicate that the minimal voltage (VH) required for retaining the CLC in the homeotropic state and the optical transparency of the CLC after treating with decreasing voltage (from VH to zero) are dependent on the voltage frequency. The observed frequency modulated electro-optical properties are characterized by the frequency regimes separated by the critical frequencies of flexoelectric polarization and dielectric relaxation in dielectric dispersion. These unusual features, specific to the CB7CB-doped CLC, are explained by the dielectric and frequency-dependent flexoelectric responses of LC molecules to an external AC voltage. Accordingly, in addition to the known Grandjean planar and focal conic states, the uniform lying helix as a third stable state can be feasibly generated in the binary CLC with 45 wt% CB7CB by two pathways. The first one is to treat the cell directly with a sufficient voltage lower than VH; the other is to decrease the voltage gradually from VH to zero in the low-frequency regime, where the flexoelectric strength is significant. Manifested by its optical tristability, frequency-controllable optical transparency, and fast flexoelectro-optical response, the proposed binary rod-like/bent-core CLC system is promising for developing a variety of memory- and dynamic-mode photonic and optoelectronic devices.

中文翻译：

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二元棒状/弯曲核胆甾型液晶的调频纹理形成和光学特性

我们探索了由具有正介电各向异性的棒状向列型 LC E7 和具有大挠曲电性的弯曲核心 LC 二聚体 CB7CB 组成的二元胆甾型液晶 (CLC) 的电压诱导纹理切换机制和相应的电光响应。系数。我们的结果表明，将 CLC 保持在垂直状态所需的最小电压 (VH) 和 CLC 在降低电压（从 VH 到零）处理后的光学透明度取决于电压频率。观察到的调频电光特性的特征在于由挠曲电极化的临界频率和介电色散中的介电弛豫所分隔的频率范围。这些不寻常的功能，特定于 CB7CB 掺杂的 CLC，可以通过 LC 分子对外部 AC 电压的介电和频率相关的挠曲电响应来解释。因此，除了已知的 Grandjean 平面和焦点圆锥状态外，作为第三种稳定状态的均匀平躺螺旋可以通过两种途径在具有 45 wt% CB7CB 的二元 CLC 中可行地产生。第一种是用低于VH的足够电压直接处理电池；另一种方法是在挠曲电强度显着的低频区域将电压从 VH 逐渐降低到零。所提出的二元棒状/弯曲核心 CLC 系统以其光学三稳定性、频率可控的光学透明度和快速的柔性光电响应表现出来，有望用于开发各种存储和动态模式光子和光电器件。