Advanced bistable cholesteric light shutter with dual frequency nematic liquid crystal
Advanced bistable cholesteric light shutter with dual frequency nematic liquid crystal
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DOI：
10.1364/ome.2.001121
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发表时间：
2012-08-01
影响因子：
2.8
通讯作者：
Lee, Seung Hee
中科院分区：
文献类型：
--
作者：
Kumar, Pankaj;Kang, Shin-Woong;Lee, Seung Hee
本文基于双频液晶（DFLC）介电各向异性的符号反转，展示了在无任何均匀聚酰亚胺（PI）层的无聚合物双稳态胆甾相光快门中，从透明（或反射）平面（P）态到不透明（或透明）焦锥（FC）态以及反之的直接切换。通过施加低频（1 kHz）和高频（50 kHz）的方波电场实现了这种直接切换。结果是，DFLC光快门在电场关闭状态下保持双稳态的亮态和暗态，并表现出优异的电光性能。从FC态到P态的直接切换不仅使P态更加均匀，而且通过消除传统聚合物稳定胆甾相织构（PSCT）光快门切换所需的高场垂直（H）态，显著降低了切换电压。使从P态到FC态转变所施加的驱动电压相对较低（3V（峰 - 峰）/μm）。此外，有垂直PI层时，从FC态到P态的切换时间大幅缩短。结果表明，双频胆甾相液晶（DFCLC）光快门在节能显示设备和可切换窗户方面具有很大的应用前景。（C）2012美国光学学会
In this paper, a direct switching between a transparent (or reflecting) planar (P) state to an opaque (or transparent) focal conic (FC) state and vice-versa of a polymer free bistable cholesteric light shutter without any homogeneous polyimide (PI) layer, is demonstrated based on the sign inversion of dielectric anisotropy of dual frequency liquid crystal (DFLC). The direct switching was achieved by applying square wave field at low (1 kHz) and high (50 kHz) frequency. As a result, the DFLC light shutter sustains bistable bright and dark states in electric field off state and exhibits excellent electro-optic performance. The direct switching from the FC to P states not only supports more uniform P state but also significantly reduces switching voltage by eliminating the high field homeotropic (H) state required for the switching in the conventional polymer stabilized cholesteric texture (PSCT) light shutter. The driving voltage applied to make a transition from the P to FC one is relatively low (3V(p-p)/mu m). Further, switching time from FC to P state was reduced drastically with homeotropic PI layer. Results show that dual frequency cholesteric liquid crystal (DFCLC) light shutter holds a great promise for use in energy efficient display devices and switchable windows. (C)2012 Optical Society of America