具有可切换衍射角的低压液晶相栅。

A Low Voltage Liquid Crystal Phase Grating with Switchable Diffraction Angles.

机构信息

College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816, USA.

School of Electronic Science and Engineering, Southeast University, Nanjing 210018, China.

出版信息

Sci Rep. 2017 Jan 5;7:39923. doi: 10.1038/srep39923.

DOI:10.1038/srep39923

PMID:28054592

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC5214749/

Abstract

We demonstrate a simple yet high performance phase grating with switchable diffraction angles using a fringe field switching (FFS) liquid crystal (LC) cell. The LC rubbing angle is parallel to the FFS electrodes (i.e. α = 0°), leading to symmetric LC director distribution in a voltage-on state. Such a grating exhibits three unique features: 1) Two grating periods can be formed by controlling the applied voltage, resulting in switchable diffraction angles. In our design, the 1 diffraction order occurs at 4.3°, while the 2 order appears at 8.6°. 2) The required voltage to achieve peak diffraction efficiency (η~~32%) for the 1 order is only 4.4 V at λ = 633 nm as compared to 70 V for a conventional FFS-based phase grating in which α ≈ 7°, while the 2 order (η~~27%) is 15 V. 3). The measured rise and decay time for the 1 order is 7.62 ms and 6.75 ms, and for the 2 order is 0.75 ms and 3.87 ms, respectively. To understand the physical mechanisms, we also perform device simulations. Good agreement between experiment and simulation is obtained.

摘要

我们使用边缘场开关（FFS）液晶（LC）单元展示了一种具有可切换衍射角的简单但高性能的相位光栅。LC 的摩擦角与 FFS 电极平行（即 α=0°），从而在电压开启状态下产生对称的 LC 指向矢分布。这种光栅具有三个独特的特点：1）通过控制施加的电压可以形成两个光栅周期，从而实现可切换的衍射角。在我们的设计中，1 级衍射发生在 4.3°，而 2 级衍射发生在 8.6°。2）与传统的 α ≈ 7°的 FFS 基相位光栅相比，在 λ = 633nm 时，实现 1 级最大衍射效率（η~~32%）所需的电压仅为 4.4V，而 2 级（η~~27%）所需的电压为 15V。3）1 级的上升和下降时间分别为 7.62ms 和 6.75ms，2 级的上升和下降时间分别为 0.75ms 和 3.87ms。为了理解物理机制，我们还进行了器件模拟。实验和模拟结果吻合良好。