scholarly journals A Planar Fresnel Lens in Reflection Type Based on Azo-Dye-Doped Cholesteric Liquid Crystals Fabricated by Photo-Alignment

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2972
Author(s):  
Bing-Yau Huang ◽  
Ting-Hui Chen ◽  
Tzu-Yeh Chen ◽  
Jia-De Lin ◽  
Tsung-Hsien Lin ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Focal Length ◽  
Incident Light ◽  
Polarization State ◽  
Fresnel Lens ◽  
Dye Molecules ◽  
Cholesteric Liquid Crystals ◽  
Crystal Film ◽  
Photo Alignment

This paper presents a focusing efficiency and focal length tunable planar Fresnel lens in reflection type based on azo-dye-doped cholesterol liquid crystal film. The Fresnel-like pattern of a pumping beam can be formed by a Sagnac interferometer. When the azo-dye molecules are irradiated by the pumping beam, the photoalignment effect will be induced in the bright (odd) zones due to the trans–cis photoisomerization of azo-dye molecules. Thus, the structures of cholesteric liquid crystals in the odd zones will reorient from the imperfectly planar textures to the perfectly planar textures. The different structures of cholesteric liquid crystals in two adjacent zones will give rise to phase difference for the reflected light and thus function as a Fresnel lens. The focusing efficiency of the proposed Fresnel lens can be controlled by the applied voltages and affected by the polarization state of incident light. Moreover, various focal lengths of the Fresnel lens can be achieved by rewriting a different center radius of the Fresnel-like pattern.

scholarly journals Electrically Tunable Fresnel Lens in Twisted-Nematic Liquid Crystals Fabricated by a Sagnac Interferometer

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1448 ◽  
Author(s):  
Bing-Yau Huang ◽  
Tsung-Hsien Lin ◽  
Tian-Yi Jhuang ◽  
Chie-Tong Kuo
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Azo Dye ◽  
Focal Length ◽  
Fresnel Lens ◽  
Sagnac Interferometer ◽  
Alignment Effect ◽  
Twisted Nematic ◽  
Linearly Polarized ◽  
Photo Alignment

This paper presents an electrically tunable Fresnel lens in a twisted nematic liquid crystal cell fabricated by using a Sagnac interferometer. When the Fresnel-patterned green beam, formed by the Sagnac interferometer, is irradiated on the azo-dye doped liquid crystal mixture, the azo-dye molecules undergo trans–cis photoisomerization and then generate the photo-alignment effect in the bright (odd) zones. The director of the liquid crystal molecules in the odd zones reorients the direction perpendicular to the polarization direction of the linearly polarized green beam. The various structures of liquid crystals in the odd and even zones will result in a phase difference and thus, a Fresnel lens can be generated. The experimental results show that the proposed Fresnel lens has a high diffraction efficiency of 31.5% under an applied alternating-currents (AC) voltage. The focal length of the Fresnel lens can also be tuned by thermally erasing the photo-alignment effect of the azo dyes and rewriting by a different Fresnel-like pattern.

scholarly journals Patterned Photoalignment in Thin Films: Physics and Applications

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 84
Author(s):  
Vladimir Chigrinov ◽  
Aleksey Kudreyko ◽  
Qi Guo
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Rotational Diffusion ◽  
Incident Light ◽  
Polarized Light ◽  
Photonic Devices ◽  
Dye Molecules ◽  
Ferroelectric Liquid Crystals ◽  
Dependent Change ◽  
Alignment Process

Photoalignment of liquid crystals by using azo dye molecules is a commonly proposed alternative to traditional rubbing alignment methods. Photoalignment mechanism can be well described in terms of rotational diffusion of azo dye molecules exposed by ultraviolet polarized light. A specific feature of the irradiated light is the intensity dependent change of azimuthal anchoring of liquid crystals. While there are various mechanisms of azo dye photoalignment, photo-reorientation occurs when dye molecules orient themselves perpendicular to the polarization of incident light. In this review, we describe both recent achievements in applications of photoaligned liquid crystal cells and its simulation. A variety of display and photonic devices with azo dye aligned nematic and ferroelectric liquid crystals are presented: q-plates, optically rewritable flexible e-paper (monochromatic and color), and Dammann gratings. Some theoretical aspects of the alignment process and display simulation are also considered.

Photo-alignment of liquid crystals in micro capillaries with point-by-point irradiation

2014 ◽  
Vol 22 (3) ◽  
Author(s):  
A. Siarkowska ◽  
M. Jóźwik ◽  
S. Ertman ◽  
T. Woliński ◽  
V. Chigrinov
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Azo Dye ◽  
Laser Light ◽  
Alignment Method ◽  
Uv Laser ◽  
Orientation Control ◽  
Photo Alignment

AbstractA photo-alignment method for micro capillaries based on the SD-1 azo-dye is demonstrated. In this work a liquid-crystal molecules aligning layer is created by point-by-point irradiation of the azo-dye film by using an UV laser light. The method opens up new possibilities for an improved molecules’ orientation control in both glass- and polymer-based photonic liquid crystal fibres.

Photoexcitation and diffusion of azo dye molecules in nematic liquid crystals

1998 ◽  
Author(s):  
Bendaoud Saad ◽  
Marie-Marguerite Denariez-Roberge ◽  
Tigran V. Galstian
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Nematic Liquid Crystals ◽  
Dye Molecules ◽  
And Diffusion

All-optical switchable holographic Fresnel lens based on azo-dye-doped polymer-dispersed liquid crystals

2011 ◽  
Vol 50 (22) ◽  
pp. 4295 ◽  
Author(s):  
Hossein Jashnsaz ◽  
Nahid Hosain Nataj ◽  
Ezeddin Mohajerani ◽  
Amir Khabbazi
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Fresnel Lens ◽  
Polymer Dispersed Liquid Crystals ◽  
All Optical ◽  
Polymer Dispersed ◽  
Doped Polymer

scholarly journals Photo-patterning micro-mirror devices using azo dye-doped cholesteric liquid crystals

2006 ◽  
Vol 14 (10) ◽  
pp. 4479 ◽  
Author(s):  
Tsung-Hsien Lin ◽  
Yuhua Huang ◽  
Ying Zhou ◽  
Andy Y. Fuh ◽  
Shin-Tson Wu
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Cholesteric Liquid Crystals

scholarly journals Reduced-Threshold Emission of Capillary Filled by Doped-Dye Cholesteric Liquid Crystals With Photo-Alignment Polyimide Films

2018 ◽  
Vol 10 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Yue-Lan Lu ◽  
Xiang-Bao Yin ◽  
Zuo-Ren Xiong ◽  
Yue Yang ◽  
Wei-Min Sun ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Cholesteric Liquid Crystals ◽  
Polyimide Films ◽  
Photo Alignment

Tunable Optical Filter with Variable Bandwidth Based on Cholesteric Liquid Crystal

2011 ◽  
Vol 181-182 ◽  
pp. 273-276
Author(s):  
Shi Chao Zhang ◽  
Yu Hua Huang
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Incident Light ◽  
Cholesteric Liquid Crystal ◽  
Optical Filter ◽  
Tunable Filter ◽  
Cholesteric Liquid Crystals ◽  
Central Wavelength ◽  
Variable Bandwidth ◽  
Tunable Optical Filter

An optical tunable filter with variable bandwidth has been demonstrated using two cholesteric liquid crystals. The incident light was first reflected by the first cholesteric liquid crystal and then by the second one. By rotating the two cholesteric liquid crystals simultaneously, the central wavelength can be tuned. By fixing one of the cholesteric liquid crystals and rotating the other one, the bandwidth of the tunable filter can be varied. The central wavelength of the tunable optical filter can be tuned from 513.4 nm to 576.8 nm and the bandwidth is varied from 10 nm to 80 nm. This property will allow it to be widely used in many fields, including optical communications and multispectral and hyperspectral imaging systems.

Optically controllable and focus-tunable Fresnel lens in azo-dye-doped liquid crystals using a Sagnac interferometer

2011 ◽  
Vol 36 (8) ◽  
pp. 1311 ◽  
Author(s):  
Hui-Chen Yeh ◽  
Yi-Chieh Kuo ◽  
Shih-Hung Lin ◽  
Jia-De Lin ◽  
Ting-Shan Mo ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Azo Dye ◽  
Fresnel Lens ◽  
Sagnac Interferometer
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