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Electrically tunable cholesteric optical filters

电可调胆甾型滤光片

基本信息

批准号：
1906104
负责人：
Oleg Lavrentovich
金额：
$ 45万
依托单位：
Kent State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-15 至 2022-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1906104&HistoricalAwards=false
关键词：
Electrically tunable cholesteric optical filters

项目摘要

General description. Optical imaging is a cornerstone of our interaction with the surrounding world. In some cases, this interaction does not require any special instruments, as Nature provided humans with power of sight. Technological applications in areas such as biomedical and chemical analysis, food and agriculture, aerospace and defense increasingly rely on the ability to control light transmittance and reflectance, to separate different "colors" of light. The project proposes to develop simple and compact devices that could selectively reflect or transmit different colors of light in a broad range from ultraviolet to visible and infrared parts of the spectrum. The idea is to use a newly discovered liquid crystal structure with electrically controlled periodicity. The device represents a thin film of the liquid crystal sandwiched between two transparent electrodes. By changing the applied voltage, one changes the period of the structure and thus s the colors of light transmitted or reflected by the film. The device will help to image details that are not accessible by a human eye. The objectives are to characterize experimentally and theoretically electro-optical performance of these liquid crystalline films in various device geometries with controlled direction of light propagation, to explore them as tunable reflectors, diffraction gratings, light attenuators, and rotators of light polarization. The project has the potential for enormous societal benefits in areas ranging from existing technologies (such as improved displays) to new technologies, such as tunable "smart windows", shutters, attenuators, tunable lasers, optical limiters, polarization rotators. The proposed research provides a superb platform to educate students at graduate and undergraduate levels in materials science, electro-optic phenomena, optics, and advanced microscopy. Technical description. The current challenge in the field of optical imaging and especially multispectral imaging can be formulated as a two-fold task: (1) to find the means to easily select and adjust the spectral bands parameters such as peak wavelength and bandwidth and (2) to make the spectral imaging compact and affordable. This project proposes to develop new electrically tunable optical filters based on cholesteric liquid crystals (LCs) with oblique helicoidal structure (ChOH) that would fulfill both of the requirements above. ChOH, discovered very recently, features a single-mode modulation of the optic axis (the director of molecular orientations) with a period that is tunable by the applied electric field. The intellectual significance is in unveiling the potential of ChOH electro-optics in a broad spectral range from UV to Vis and IR. The oblique helicoidal structure of ChOH with periodic modulation of the director but homogeneous molecular density is new to the field of LCs and soft matter in general. Its predecessor, the so-called twist-bend nematic phase NTB, has been discovered only a few years ago and is currently enjoying an explosive growth of research as the fine details of the oblique helicoidal structures and their response to the external fields are not understood well. The proposed research will result in the new knowledge of how the structure of ChOH is shaped by the externally applied electric field and confinement geometry and how ChOH can be used in the design and fabrication of the new generation of electrically tunable optical elements such as filters, gratings, polarization rotators, attenuators. The electrically adjustable period of ChOH represents a new mode of the electro-optical response of LCs. The transformative value of the project is in the potential for new design concepts for tunable electro-optical devices performing in a broad spectral range from UV to Vis and IR.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

一般描述。光学成像是我们与周围世界互动的基石。在某些情况下，这种相互作用不需要任何特殊的工具，因为大自然为人类提供了视觉的力量。生物医学和化学分析、食品和农业、航空航天和国防等领域的技术应用越来越依赖于控制光透射率和反射率的能力，以分离不同“颜色”的光。该项目建议开发简单紧凑的设备，可以选择性地反射或透射光谱中从紫外线到可见光和红外线部分的广泛范围内的不同颜色的光。这个想法是使用一种新发现的具有电控周期性的液晶结构。该器件代表了夹在两个透明电极之间的液晶薄膜。通过改变所施加的电压，人们改变了结构的周期，从而改变了被膜透射或反射的光的颜色。该设备将有助于图像的细节是无法访问的人眼。目的是在实验和理论上表征这些液晶薄膜在各种器件几何形状与控制的光传播方向的电光性能，探索它们作为可调反射器，衍射光栅，光衰减器，和旋转器的光偏振。该项目在现有技术（如改进的显示器）和新技术（如可调“智能窗”、快门、衰减器、可调激光器、光学限幅器、偏振旋转器）等领域具有巨大的社会效益潜力。拟议的研究提供了一个极好的平台，教育学生在材料科学，电光现象，光学和先进显微镜的研究生和本科生水平。技术说明。光学成像领域，特别是多光谱成像领域的当前挑战可以被表述为双重任务：（1）找到容易地选择和调整光谱带参数（例如峰值波长和带宽）的手段，以及（2）使光谱成像紧凑且可负担得起。本计画提出发展一种新的电性可调光学滤波器，此滤波器是以具有斜螺旋结构的液晶为基础，以满足上述两种需求。最近发现的ChOH具有光轴（分子取向的指向矢）的单模调制，其周期可通过施加的电场进行调谐。知识的意义在于揭示了ChOH电光在从UV到维斯和IR的宽光谱范围内的潜力。ChOH的斜螺旋结构具有指向矢的周期性调制，但均匀的分子密度对于LC和软物质领域是新的。它的前身，所谓的扭曲-弯曲双相NTB，仅在几年前被发现，目前正享受着爆炸性增长的研究，因为斜螺旋结构的细节及其对外场的响应还没有很好地理解。该研究将为ChOH的结构如何通过外加电场和限制几何形状形成以及ChOH如何用于设计和制造新一代电可调谐光学元件如滤波器，光栅，偏振旋转器，衰减器提供新的知识。ChOH的电可调周期代表了LC电光响应的一种新模式。该项目的变革性价值在于可调谐电光设备的新设计概念的潜力，这些设备在从紫外到维斯和红外的广泛光谱范围内执行。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Electromagnetically tunable cholesterics with oblique helicoidal structure [Invited]

具有斜螺旋结构的电磁可调胆甾醇 [邀请]

DOI：
10.1364/ome.403810
发表时间：
2020
期刊：
Optical Materials Express
影响因子：
2.8
作者：
Lavrentovich, Oleg D.
通讯作者：
Lavrentovich, Oleg D.

In situ measurements of twist and bend elastic constants in the oblique helicoidal cholesteric

斜螺旋胆甾型扭转和弯曲弹性常数的原位测量

DOI：
10.1103/physreve.106.024702
发表时间：
2022
期刊：
Physical Review E
影响因子：
2.4
作者：
Iadlovska, Olena S.;Thapa, Kamal;Rajabi, Mojtaba;Shiyanovskii, Sergij V.;Lavrentovich, Oleg D.
通讯作者：
Lavrentovich, Oleg D.

Optical control of light polarization in heliconical cholesteric liquid crystals

螺旋胆甾型液晶中光偏振的光学控制

DOI：
10.1364/ol.454431
发表时间：
2022
期刊：
Optics Letters
影响因子：
3.6
作者：
Nava, G.;Barboza, R.;Simoni, F.;Iadlovska, O.;Lavrentovich, O. D.;Lucchetti, L.
通讯作者：
Lucchetti, L.

Heliconical cholesteric liquid crystals as electrically tunable optical filters in notch and bandpass configurations

螺旋胆甾液晶作为陷波和带通配置的电可调光学滤波器

DOI：
10.1080/02678292.2021.1884911
发表时间：
2021
期刊：
Liquid Crystals
影响因子：
2.2
作者：
Nava, G.;Ciciulla, F.;Simoni, F.;Iadlovska, O.;Lavrentovich, O. D.;Lucchetti, Liana
通讯作者：
Lucchetti, Liana

Temperature dependence of bend elastic constant in oblique helicoidal cholesterics

斜螺旋胆甾型材料弯曲弹性常数的温度依赖性

DOI：
10.1103/physrevresearch.2.013248
发表时间：
2020
期刊：
Physical Review Research
影响因子：
4.2
作者：
Iadlovska, Olena S.;Babakhanova, Greta;Mehl, Georg H.;Welch, Christopher;Cruickshank, Ewan;Strachan, Grant J.;Storey, John M.;Imrie, Corrie T.;Shiyanovskii, Sergij V.;Lavrentovich, Oleg D.
通讯作者：
Lavrentovich, Oleg D.