Transient laser phenomena in nematic liquid crystals subject to ac electric fields

1974 ◽  
Vol 24 (11) ◽  
pp. 529-531 ◽  
Author(s):  
W. S. Quon ◽  
E. Wiener‐Avnear
Keyword(s):  
Liquid Crystals ◽  
Electric Fields ◽  
Nematic Liquid Crystals ◽  
Ac Electric Fields

scholarly journals Electrically Controlled Diffraction Grating in Azo Dye-Doped Liquid Crystals

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1051 ◽  
Author(s):  
Chuen-Lin Tien ◽  
Rong-Ji Lin ◽  
Chi-Chung Kang ◽  
Bing-Yau Huang ◽  
Chie-Tong Kuo ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Fields ◽  
Azo Dye ◽  
Nematic Liquid Crystals ◽  
Polarized Light ◽  
Dielectric Anisotropy ◽  
Linear Effect ◽  
Periodic Distribution ◽  
The Difference

This research applies the non-linear effect of azo dye-doped liquid crystal materials to develop a small, simple, and adjustable beam-splitting component with grating-like electrodes. Due to the dielectric anisotropy and optical birefringence of nematic liquid crystals, the director of the liquid crystal molecules can be reoriented by applying external electric fields, causing a periodic distribution of refractive indices and resulting in a diffraction phenomenon when a linearly polarized light is introduced. The study also discusses the difference in the refractive index (Δn), the concentration of azo dye, and the rising constant depending on the diffraction signals. The experimental results show that first-order diffraction efficiency can reach ~18% with 0.5 wt % azo dye (DR-1) doped in the nematic liquid crystals.

ELECTRO-OPTICAL PHENOMENA DUE TO INFLUENCE OF LIGHT BEAMS ON MATERIAL PARAMETERS OF LIQUID CRYSTALS

1999 ◽  
Vol 08 (03) ◽  
pp. 389-401 ◽  
Author(s):  
NELSON V. TABIRYAN ◽  
CESARE UMETON
Keyword(s):  
Liquid Crystals ◽  
Electric Fields ◽  
Diffusion Processes ◽  
Material Parameters ◽  
Ac Electric Fields ◽  
Absorption Of Light ◽  
Optical Phenomena ◽  
Light Beams

Modulation of material parameters of liquid crystals (LC) due to absorption of light beams allows to control the reorientation of the LC under the influence of ac electric fields. Particularly, it makes possible recording of photorefractive-like orientation gratings. Such gratings are phase shifted with respect to the pattern of interfering light beams. The material and external parameters determine the magnitude of the shift. These photorefractive-like phase shifted gratings are stationary, and no diffusion processes are involved in their build-up.

Behaviour of Nematic Liquid Crystals in Inhomogeneous Electric Fields

1979 ◽  
Vol 55 (1) ◽  
pp. 193-207 ◽  
Author(s):  
V. G. Chigrinov ◽  
I. N. Kompanets ◽  
A. A. Vasiliev
Keyword(s):  
Liquid Crystals ◽  
Electric Fields ◽  
Nematic Liquid Crystals

scholarly journals Patterns driven by combined ac and dc electric fields in nematic liquid crystals

2014 ◽  
Vol 89 (5) ◽  
Author(s):  
Alexei Krekhov ◽  
Werner Decker ◽  
Werner Pesch ◽  
Nándor Éber ◽  
Péter Salamon ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Electric Fields ◽  
Nematic Liquid Crystals ◽  
Dc Electric Fields

Nematic liquid crystals in frequency and amplitude modulated electric fields

2001 ◽  
Vol 28 (7) ◽  
pp. 973-982 ◽  
Author(s):  
B. I. Lev ◽  
V. N. Sergienko ◽  
P. M. Tomchuk ◽  
E. K. Frolova
Keyword(s):  
Liquid Crystals ◽  
Electric Fields ◽  
Nematic Liquid Crystals

A Novel Method for Measuring the Difference in Flexoelectric Coefficients of Nematic Liquid Crystals

2011 ◽  
Vol 181-182 ◽  
pp. 26-32
Author(s):  
Benjamin I. Outram ◽  
Steve J. Elston
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystal ◽  
Electric Fields ◽  
Nematic Liquid Crystals ◽  
Angle Of Incidence ◽  
Rotation Method ◽  
Twisted Nematic ◽  
Novel Method ◽  
The Difference

The difference between e1 and e3 parameters for flexoelectric polarization, as originally defined byMeyer, is measured for nematic liquid crystal materials E7 and BL087 in Twisted Nematic (TN) cells with In-Plane Switching (IPS) electric fields using the crystal rotation method, which measures transmission as a function of angle of incidence. Values of e1 − e3 for E7 and BL087 are found to be 7.2±1.0 pCm−1 and 9.4±1.0 pCm−1 respectively.

scholarly journals Dynamic FT-IR spectroscopy of liquid crystals and polymer films

1993 ◽  
Author(s):  
Βασίλειος Γρηγορίου
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Fields ◽  
Polymer Films ◽  
Spectroscopic Techniques ◽  
Ac Electric Fields ◽  
Pulsed Dc ◽  
Ft Ir ◽  
Reorientation Dynamics ◽  
Director Reorientation

This dissertation describes the use of continuous-scan and step-scan Fourier transform infrared (FT-IR) spectroscopic techniques to study the dynamics of the response of polymer films and liquid crystals to external perturbations. The investigation of liquid crystals includes both nematic and chiral smectic C examples. In these studies the dynamic infrared absorbance is used to explore the submolecular (functional group) contributions to the reorientation dynamics of the liquid crystal director in response to both pulsed (DC) and modulated (AC) electric fields. Continuous-scan stroboscopic FT-IR and step-scan impulse-response FT-IR were used to analyze the rise dynamics of reorientation resulting from pulsed DC perturbations; whereas step-scan FT-IR was used to monitor both rise and decay processes in response to synchronously modulated (AC) electric fields. In the step-scan measurements this sub-molecular view of the dynamics of liquid crystal director reorientation was enhanced by frequency correlation analysis, to yield 2D FT-IR spectra. For the nematic liquid crystal 4-pentyl-4$\sp\prime$-cyanobiphenyl (5CB) the data suggest a different rate of response of the rigid and floppy parts of the LC molecules. The second application of dynamic step-scan FT-IR reported is the study of the response of various polymer films to sinusoidally modulated tensile strain. The main advantage of the technique is that it can provide valuable information at the molecular level that can be used to interpret the macroscopic properties of the polymeric material under investigation. Examples of application to different types of polymer films are presented. Results for several heterogeneous polymers including semicrystalline high density/low density polyethylene blends, the micro-phase separated copolymer Kraton$\sp\circler$ and a homogeneous polymer blend of polystyrene/polydimethylphenylene oxide are presented. Finally, the modification of a research-grade FT-IR spectrometer (Nicolet Instruments, System 800) for step-scan operation is described. Some applications of the instrument to photoacoustic spectroscopy (PAS) are presented.

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