Variable pitch hydrodynamic electro-optic gratings utilising bent liquid crystal dimers.
Variable pitch hydrodynamic electro-optic gratings utilising bent liquid crystal dimers.
复制标题
DOI：
10.1039/d0sm01425g
复制
发表时间：
2020-10
期刊：
影响因子：
3.4
通讯作者：
R. Morris;John Clifford Jones;Mamatha Nagaraj
中科院分区：
文献类型：
--
作者：
R. Morris;John Clifford Jones;Mamatha Nagaraj
液晶中的电流体动力学不稳定性（EHDI）在受到某些材料和几何形状确定的条件时形成均匀且连续可变的衍射结构。一维光栅是一种这样的衍射结构，其中折射率在平行于初始液晶指向矢的方向上周期性地变化。该结构的周期先前已经被示出为近似地在单元间隙和半单元间隙的值之间连续变化，从而允许光束的连续角度调制，但是具有有限的角度范围。在这项工作中，较低的节距限制被示出也部分地由液晶的展曲和弯曲弹性常数的比率（k11/k33）控制。与标准的弹性常数比（K11/K33 - 5）比以前在文献EHDI研究中使用的主机液晶。在这种新的混合物中形成的EHDI光栅表现出明显低于半盒间隙的间距长度，允许高达50%的更宽角度的光连续转向。这提高了在光束控制和衍射光学器件中的应用潜力。
Electrohydrodynamic instabilities (EHDI) in liquid crystals form uniform and continuously variable diffractive structures when subject to certain material and geometry determined conditions. A one-dimensional grating is one such diffractive structure, where the refractive index changes periodically in a direction parallel to the initial liquid crystal director. The period of this structure has been shown previously to vary continuously between the values of the cell gap and half-cell gap approximately, allowing continuous angular modulation of optical beams but with a limited angular range. In this work, the lower pitch limit is shown to also be governed in part by the ratio of the splay and bend elastic constants (k11/k33) of the liquid crystal. A host nematic liquid crystal with standard elastic constant ratios (k11/k33 5) than for those previously used in literature EHDI studies. The EHDI gratings formed in this new mixture exhibit pitch lengths significantly below half-cell gap, allowing up to 50% wider angle continuous steering of light. This improves the potential for application in beamsteering and diffractive optical devices.