P-Cyanoazobenzene as a command molecule for azimuthal anisotropy regulation of a nematic liquid crystal upon exposure to linearly polarized visible light

Langmuir ◽  
1993 ◽  
Vol 9 (3) ◽  
pp. 857-860 ◽  
Author(s):  
Kunihiro Ichimura ◽  
Yuko Hayashi ◽  
Yuji Kawanishi ◽  
Takahiro Seki ◽  
Takashi Tamaki ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Visible Light ◽  
Nematic Liquid Crystal ◽  
Azimuthal Anisotropy ◽  
Linearly Polarized

OPTICAL ANISOTROPY AND FOUR POSSIBLE ORIENTATIONS OF A NEMATIC LIQUID CRYSTAL ON THE SAME FILM OF A PHOTOCHROMIC CHIRAL SMECTIC POLYMER

2000 ◽  
Vol 09 (01) ◽  
pp. 1-10 ◽  
Author(s):  
LEV M. BLINOV ◽  
RICCARDO BARBERI ◽  
MIKHAIL V. KOZLOVSKY ◽  
VLADIMIR V. LAZAREV ◽  
MARIA P. DE SANTO
Keyword(s):  
Liquid Crystal ◽  
Visible Light ◽  
Nematic Liquid Crystal ◽  
Optical Anisotropy ◽  
Liquid Crystalline ◽  
Uv Light ◽  
Glassy State ◽  
Electric Vector ◽  
Exciting Light ◽  
Linearly Polarized

Spin coated films of a chiral comb-like liquid crystalline copolymer containing azobenzene chromophores in its side chains are optically isotropic in their twisted smectic-like glassy state. In contact with a nematic liquid crystal (5CB, E7, MBBA) they provide a degenerate planar orientation. When irradiated by unpolarized UV light, they orient the same nematics homeotropically. Treated with linearly polarized UV light they orient nematics homogeneously with the director along the electric vector of the exciting light. After a combined irradiation first with unpolarized UV light and then with linearly polarized visible light, the films again provide a homogeneous liquid crystal orientation, this time with the director perpendicular to the visible light electric vector. The phenomena observed are related to the light induced optical anisotropy. Two main processes are responsible for the anisotropy (1) a UV light depletion of trans-isomers of the azobenzene chromophores from the chosen direction and (2) a reorientation of the chromophores by polarized visible light.

Generation of nematic liquid crystal alignment with polyimides exposed to linearly polarized light of long wavelength

1998 ◽  
Vol 84 (1) ◽  
pp. 181-188 ◽  
Author(s):  
Yinghan Wang ◽  
Chunying Xu ◽  
Akihiko Kanazawa ◽  
Takeshi Shiono ◽  
Tomiki Ikeda ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Polarized Light ◽  
Long Wavelength ◽  
Liquid Crystal Alignment ◽  
Linearly Polarized ◽  
Crystal Alignment

ON THE BEHAVIOR OF POLARIZED LIGHT IN TWIST-ORIENTED NEMATIC LIQUID CRYSTALS WITH ANISOTROPIC ABSORBENT DYE

2020 ◽  
Vol 54 (1 (251)) ◽  
pp. 56-60
Author(s):  
H.H. Hovakimyan
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystal ◽  
Azimuthal Angle ◽  
Polarized Light ◽  
Transmitted Light ◽  
Propagation Of Light ◽  
Linearly Polarized ◽  
Incoming Light

In this work we study the propagation of light in a twist-oriented pleochroic nematic liquid crystal with pleochroic dye. The dependence of the intensity of transmitted light on the azimuthal angle of the linearly polarized incoming light has been investigated experimentally. As a result, the role of absorption anisotropy has been identified.

scholarly journals Anomalous Lehmann Rotation of Achiral Nematic Liquid Crystal Droplets Trapped under Linearly Polarized Optical Tweezers

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4108
Author(s):  
Jarinee Kiang-ia ◽  
Rahut Taeudomkul ◽  
Pongthep Prajongtat ◽  
Padetha Tin ◽  
Apichart Pattanaporkratana ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Optical Tweezers ◽  
Nematic Liquid Crystal ◽  
Laser Power ◽  
Optical Trap ◽  
Laser Trapping ◽  
Laser Trap ◽  
Continuous Rotation ◽  
Linearly Polarized ◽  
Optical Levitation

Continuous rotation of a cholesteric droplet under the heat gradient was observed by Lehmann in 1900. This phenomenon, the so-called Lehmann effect, consists of unidirectional rotation around the heat flux axis. We investigate this gradient heat effect using infrared laser optical tweezers. By applying single trap linearly polarized optical tweezers onto a radial achiral nematic liquid crystal droplet, trapping of the droplet was performed. However, under a linearly polarized optical trap, instead of stable trapping of the droplet with slightly deformed molecular directors along with a radial hedgehog defect, anomalous continuous rotation of the droplet was observed. Under low power laser trapping, the droplet appeared to rotate clockwise. By continuously increasing the laser power, a stable trap was observed, followed by reverse directional rotation in a higher intensity laser trap. Optical levitation of the droplet in the laser beam caused the heat gradient, and a breaking of the symmetry of the achiral nematic droplet. These two effects together led to the rotation of the droplet under linearly polarized laser trapping, with the sense of rotation depending on laser power.

scholarly journals Influence of X7GeS5I (X = Ag, Cu) Superionic Nanoparticles on Structural Changes in Nematic Liquid Crystal

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 413
Author(s):  
Peter Bury ◽  
Marek Veveričík ◽  
Peter Kopčanský ◽  
Milan Timko ◽  
Ihor P. Studenyak ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Nematic Liquid Crystal ◽  
Acoustic Waves ◽  
Structural Changes ◽  
Light Transmission ◽  
Surface Acoustic Waves ◽  
Switching Behavior ◽  
Suspension Stability ◽  
Linearly Polarized

The effect of two types of superionic nanoparticles; Cu7GeS5I and Ag7GeS5I, respectively on nematic liquid crystal (6CB) behavior under an external electric field is investigated. The response of both attenuation of surface acoustic waves propagating along with the substrate/liquid crystal interface and light transmission are used to study the structural changes induced by applied electric field. The increasing/decreasing regime as well as jumped change of applied field were used. The light transmission was investigated using linearly polarized laser beam (532 nm) propagating through the liquid crystal. Results obtained from both measurements for three different concentrations (0.01, 0.05 and 0.10 wt%) and in addition two different sizes of nanoparticles are compared and results, relying on structural changes, suspension stability and switching behavior are evaluated.

scholarly journals Геометрическая оптика твист-ориентированного нематического жидкого кристалла с анизотропным поглощением

2019 ◽  
Vol 127 (11) ◽  
pp. 787
Author(s):  
А.О. Овакимян ◽  
А.Э. Айвазян ◽  
Л.С. Асланян
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Anisotropic Medium ◽  
Light Propagation ◽  
Light Wave ◽  
Spatial Dynamics ◽  
Polarized Light ◽  
Asymmetric Effect ◽  
Electric Component ◽  
Linearly Polarized

The spatial dynamics of polarized light in a smoothly inhomogeneous anisotropic medium mixed with an anisotropic absorbing dye is analyzed. As such a medium, a twist-oriented nematic liquid crystal with a pleochroic dye was considered. In the geometrical-optical approximation, a system of coupled shortened equations for the Cartesian components of the electric component of the light wave is obtained. A system of coupled complex equations was analytically solved and the behavior of a linearly polarized wave in such a medium was analyzed in the case of both absorption and amplification. An asymmetric effect of these two processes on the spatial dynamics of light propagation in the medium is found.

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