Electro-patterning and diffraction properties in negative liquid crystals

Xiaohu SHANG; Haoyi JIANG; Zhenpeng SONG; Jiao LIU; Bingxiang LI

doi:10.37188/CJLCD.2023-0263

Chinese Journal of Liquid Crystals and Displays, Volume. 39, Issue 3, 312(2024)

Electro-patterning and diffraction properties in negative liquid crystals

Xiaohu SHANG, Haoyi JIANG^#, Zhenpeng SONG, Jiao LIU^*, and Bingxiang LI^**

College of Electronic and Optical Engineering and College of Flexible Electronics （Future Technology）， Nanjing University of Posts and Telecommunications， Nanjing 210023， China

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Fig. 1. （a） $ε_{∥}$ and $ε_{⊥}$ of liquid crystal （HNG708600-100） as a function of frequency at $T = 30 ℃$ and $T = 70 ℃$ ；（b） $Δ ε$ as a function of temperature at $f = 20 k H z$ .

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$POM images of patterns in nematic liquid crystal material （HNG708600-100）. （a） f=30 Hz， T=70 ℃；（b） f=30 Hz， T=40 ℃， Patterns： P1 （soft square）， P2 （oblique rolls）， P3 （skewed varicose）， and P4 （irregular patterns）. The inset pictures show the diffraction characteristics for each pattern；（c）Threshold voltages of different patterns at T=70 ℃， T=60 ℃ and T=40 ℃；（d） Threshold voltages of patterns at different temperature： soft square， oblique rolls and irregular patterns. The initial director is horizontal， the analyzer and polarizer are aligned perpendicularly， the thickness of cell d=8.3 μm， and the scale bars are all 25 μm.$

Fig. 2. POM images of patterns in nematic liquid crystal material （HNG708600-100）. （a） $f = 30 H z$ ， $T = 70 ℃$ ；（b） $f = 30 H z$ ， $T = 40 ℃$ ， Patterns： P1 （soft square）， P2 （oblique rolls）， P3 （skewed varicose）， and P4 （irregular patterns）. The inset pictures show the diffraction characteristics for each pattern；（c）Threshold voltages of different patterns at $T = 70 ℃$ ， $T = 60 ℃$ and $T = 40 ℃$ ；（d） Threshold voltages of patterns at different temperature： soft square， oblique rolls and irregular patterns. The initial director is horizontal， the analyzer and polarizer are aligned perpendicularly， the thickness of cell $d = 8.3 μ m$ ， and the scale bars are all $25 μ m$ .

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$（a） POM images of various soft square at different frequencies， and the inset pictures show the corresponding diffraction patterns；（b） Intensity distribution of the soft square pattern along with x axis. （c） Periodicity Px and Py as a function of voltage at f=40 Hz；（d） Periodicity Px and Py， diffraction spot spacing Lx and Ly as a function of frequency. T=40 ℃， the initial director is horizontal， the thickness of cell d=8.3 μm， and all the scale bars are 25 μm.$

Fig. 3. （a） POM images of various soft square at different frequencies， and the inset pictures show the corresponding diffraction patterns；（b） Intensity distribution of the soft square pattern along with $x$ axis. （c） Periodicity $P_{x}$ and $P_{y}$ as a function of voltage at $f = 40 H z$ ；（d） Periodicity $P_{x}$ and $P_{y}$ ， diffraction spot spacing $L_{x}$ and $L_{y}$ as a function of frequency. $T = 40 ℃$ ， the initial director is horizontal， the thickness of cell $d = 8.3 μ m$ ， and all the scale bars are $25 μ m$ .

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$（a） Intensity distribution along the normal direction of oblique rolls at f=70 Hz and U=34.4 V， and the inset pictures are POM image of the oblique rolls （left） and the corresponding diffraction pattern （right）， where L represents the spacing between diffraction patterns；（b） Periodicity P as a function of voltage at f=70 Hz；（c） Periodicity P and the space of diffraction spots L as a function of frequency. T=40℃， the initial director is horizontal along the rubbing direction， and the thickness of cell d=8.3 μm.$

Fig. 4. （a） Intensity distribution along the normal direction of oblique rolls at $f = 70 H z$ and $U = 34.4 V$ ， and the inset pictures are POM image of the oblique rolls （left） and the corresponding diffraction pattern （right）， where L represents the spacing between diffraction patterns；（b） Periodicity P as a function of voltage at $f = 70 H z$ ；（c） Periodicity P and the space of diffraction spots L as a function of frequency. $T = 40 ℃$ ， the initial director is horizontal along the rubbing direction， and the thickness of cell $d = 8.3 μ m$ .

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$（a） POM images of oblique rolls at U=16.9 V and different frequency （f=30， 34， 43 Hz） and corresponding diffraction characteristics；（b） Variations of α60 with frequency at T=60 ℃ and U=16.9 V； α40 at T=40 ℃ and U=23.0 V；（c） Variations α60 of oblique rolls with respect to the director with voltage at f=30 Hz and f=40 Hz；（d）， P changed with the frequency at T=60 ℃. The initial director is horizontal， the thickness of cell d=8.3 μm， and the scale bars are all 25 μm.$

Fig. 5. （a） POM images of oblique rolls at $U = 16.9 V$ and different frequency （ $f = 30$ ， 34， $43 H z$ ） and corresponding diffraction characteristics；（b） Variations of $α_{60}$ with frequency at $T = 60 ℃$ and $U = 16.9 V$ ； $α_{40}$ at $T = 40 ℃$ and $U = 23.0 V$ ；（c） Variations $α_{60}$ of oblique rolls with respect to the director with voltage at $f = 30 H z$ and $f = 40 H z$ ；（d）， P changed with the frequency at T=60 ℃. The initial director is horizontal， the thickness of cell $d = 8.3 μ m$ ， and the scale bars are all $25 μ m$ .

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Xiaohu SHANG, Haoyi JIANG, Zhenpeng SONG, Jiao LIU, Bingxiang LI. Electro-patterning and diffraction properties in negative liquid crystals[J]. Chinese Journal of Liquid Crystals and Displays, 2024, 39(3): 312

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Paper Information

Category: Research Articles

Received: Aug. 11, 2023

Accepted: --

Published Online: Apr. 29, 2024

The Author Email: Jiao LIU (jiaol@njupt.edu.cn), Bingxiang LI (bxli@njupt.edu.cn)

DOI:10.37188/CJLCD.2023-0263

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