Electrical Characterization of E7 Liquid Crystal Molecules under the Impact of an External Electric Field (THz): A Theoretical approach

2020 ◽  
Vol 15 (2) ◽  
pp. 95-101
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Order Parameter ◽  
Optical Switching ◽  
Rapid Change ◽  
Electrical Characterization ◽  
Optical Switching Devices ◽  
The Impact ◽  
Orientation Of Molecules

In this work, different parameters of E7 liquid crystal (LC) have been calculated under the influence of an electric field in THz frequency. The E7 LC parameters have positive as well as negative values of order parameter and birefringence under the influence for an electric field. The director angle of E7 LC shows fast fluctuations above the angle θ=45° and due to rapid change in the orientation of molecules, fast electro-optical switching devices based on E7 LC can be designed. The refractive index of the E7 LC maintains stability in THz frequency.

scholarly journals ELECTRO-OPTICAL SWITCHING OF THE MAIN OPTICAL AXIS OF A FERROELECTRIC LIQUID CRYSTAL SPIRAL NANOSTRUCTUREIN A PLANAR-ORIENTED DISPLAY CELL

Doklady BGUIR ◽  
2019 ◽  
pp. 21-27
Author(s):  
E. P. Pozhidaev ◽  
T. P. Tkachenko ◽  
A. V. Kuznetsov ◽  
I. N. Kompanets
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Optical Switching ◽  
Optical Axis ◽  
Modulation Frequency ◽  
Light Transmittance ◽  
Weak Electric Field ◽  
Ferroelectric Liquid Crystal ◽  
Light Modulation ◽  
Small Pitch

In a known display cell with the nematic liquid crystal (NLC) and interdigital electrodes on one of the glass substrates, the “In-Plane Switching” (IPS) mode is implemented, in which the NLC main optical axis reorients in a plane parallel to substrates, providing the most correct color reproduction at different angles view, up to 178 ° horizontally and vertically. Unfortunately, the creation of interdigital metal electrodes complicates and increases the technological process cost and causes a decrease in image contrast. At the same time, experimental results and calculations based on classical electro-optics of crystals indicate that electrooptical switching in the IPS mode is a natural and intrinsic feature of a conventional (with continuous electrodes) display cell with a planar-oriented layer of the ferroelectric liquid crystal (FLC), in which the effect of the deformed (by the electric field) helix FLC nanostructure is realized (DHF effect). In such a cell, the reorientation of the main optical axis under the influence of a weak electric field also occurs in the substrate plane if the FLC has a small pitch (about 100 nm or less) and a large tilt angle of molecules in the layer (about 38 ° or more). The dependences of the FLC cell light transmittance measured in this work, confirmed the achievement of the IPS electro-optical mode in the DHF FLC cell; moreover, the light modulation frequency was 1 kHz. Thus, while maintaining all the advantages of the IPS mode known in NLC, its implementation in FLC allows additionally obtaining technological advantages and multiple increase in modulation frequency.

scholarly journals Impact of Crystalline Orientation on the Switching Field in Barium Titanate Using Piezoresponse Force Spectroscopy

2014 ◽  
Vol 1652 ◽  
Author(s):  
Nikhil K. Ponon ◽  
Daniel J. R. Appleby ◽  
Erhan Arac ◽  
Kelvin S. K. Kwa ◽  
Jonathan P. Goss ◽  
...  
Keyword(s):  
Electric Field ◽  
Phase Change ◽  
Crystal Orientation ◽  
Force Spectroscopy ◽  
Ferroelectric Domain ◽  
Switching Field ◽  
The Impact ◽  
Non Destructive ◽  
Domain Level

ABSTRACTUnderstanding crystal orientation at the ferroelectric domain level, using a non destructive technique, is crucial for the design and characterization of nano-scale devices. In this study, piezoresponse force spectroscopy (PFS) is used to identify ferroelectric domain orientation. The impact of crystal orientation on the switching field of ferroelectric BaTiO3 is also investigated at the domain level. The preferential domain orientations for BaTiO3 thin films prepared by pulsed laser deposition (PLD) in this study are [001], [101] and [111]. They have been mapped onto PFS spectra to show three corresponding switching fields of 460, 330 and 120 kV/cm respectively. In addition, the electric field at which the enhanced piezoresponse occurs was found to vary, due to a phase change. The polarization reversal occurs via a 2-step process (rotation and switching) for [101] and [111] orientations. The piezoresponse enhancement is absent for the [001] (pure switching) domains. The results demonstrate that an electric field induced phase change causes the [101] and [111] domains to reverse polarization at a lower field than the [001] domain.

Electrical Characterization of Al2O3 - SiO2 Mos Structures

1999 ◽  
Vol 567 ◽  
Author(s):  
L-Å Ragnarsson ◽  
E. Aderstedt ◽  
P. Lundgren
Keyword(s):  
Electrical Characterization ◽  
Thickness Reduction ◽  
Initial Thickness ◽  
Equivalent Thickness ◽  
Conventional Furnace ◽  
Capacitance Voltage ◽  
Layered Dielectric ◽  
The Impact ◽  
Mos Structures

ABSTRACTA comparative capacitance voltage method is used to investigate the equivalent thickness reduction during post metallization annealing of thermally grown ultrathin (∼15-27 Å) oxides. It is found that a double layered dielectric consisting of a thin Al2O3—SiO2 sandwich is appropriate to describe both the increased capacitance and the nearly unaltered current after anneal. It is further shown that the impact of initial thickness and method of growth — in a conventional furnace or by rapid thermal oxidation — on the equivalent thickness reduction is negligible.

scholarly journals Nematic topological defects positionally controlled by geometry and external fields

2018 ◽  
Vol 9 ◽  
pp. 109-118 ◽  
Author(s):  
Pavlo Kurioz ◽  
Marko Kralj ◽  
Bryce S Murray ◽  
Charles Rosenblatt ◽  
Samo Kralj
Keyword(s):  
Electric Field ◽  
Topological Charge ◽  
Order Parameter ◽  
Topological Defects ◽  
Two Dimensional ◽  
External Fields ◽  
Nematic Ordering ◽  
Spatial Positioning ◽  
A Charge ◽  
The Impact

Using a Landau–de Gennes approach, we study the impact of confinement topology, geometry and external fields on the spatial positioning of nematic topological defects (TDs). In quasi two-dimensional systems we demonstrate that a confinement-enforced total topological charge of m > 1/2 decays into elementary TDs bearing a charge of m = 1/2. These assemble close to the bounding substrate to enable essentially bulk-like uniform nematic ordering in the central part of a system. This effect is reminiscent of the Faraday cavity phenomenon in electrostatics. We observe that in certain confinement geometries, varying the correlation length size of the order parameter could trigger a global rotation of an assembly of TDs. Finally, we show that an external electric field could be used to drag the boojum fingertip towards the interior of the confinement cell. Assemblies of TDs could be exploited as traps for appropriate nanoparticles, opening several opportunities for the development of functional nanodevices.

Ferroelectric liquid crystal driving method for optical switching devices in communication networks

1993 ◽  
Vol 149 (1) ◽  
pp. 159-169 ◽  
Author(s):  
Shigeto Kohda ◽  
Seiiti Shirai ◽  
Yoshie Takeuchi ◽  
Noriyoshi Yamauchi
Keyword(s):  
Liquid Crystal ◽  
Communication Networks ◽  
Optical Switching ◽  
Ferroelectric Liquid Crystal ◽  
Optical Switching Devices ◽  
Switching Devices

Thermal and Electrical Characterization of a Ferro Electric Liquid Crystal

2008 ◽  
Vol 39 (5) ◽  
pp. 1192-1195 ◽  
Author(s):  
M.L.N. Madhu Mohan ◽  
B. Arunachalam ◽  
C.R. Aravindh Sankar
Keyword(s):  
Liquid Crystal ◽  
Electrical Characterization

Optical Mode Characterization of the Configuration of a Thin Ferroelectric Liquid Crystal Cell Under an Applied Electric Field

1991 ◽  
Vol 38 (8) ◽  
pp. 1451-1461 ◽  
Author(s):  
C.R. Lavers ◽  
P.S. Cann ◽  
J.R. Sambles ◽  
E.P. Raynes
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Applied Electric Field ◽  
Liquid Crystal Cell ◽  
Ferroelectric Liquid Crystal ◽  
Optical Mode ◽  
Crystal Cell

Electric-field-induced change of the order parameter in a nematic liquid crystal

1993 ◽  
Vol 48 (5) ◽  
pp. 3818-3821 ◽  
Author(s):  
I. Lelidis ◽  
M. Nobili ◽  
G. Durand
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Nematic Liquid Crystal ◽  
Order Parameter
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