scholarly journals Liquid Crystal-Based Reconfigurable Tunable Filter with DBR Topology

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
S. Missaoui ◽  
M. Kaddour
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Bias Voltage ◽  
Tunable Filter ◽  
Measured Data ◽  
Planar Technology ◽  
Crystal Anisotropy ◽  
Good Agreement

The use of liquid crystals for tunable filter in planar technology is proposed. The design is based on a dual-behavior resonator (DBR) topology. These resonators are based on the association of different parallel open-ended stubs and allow the designer to independently control the in-band and out-of-band responses of the filter. To benefit from liquid crystal anisotropy and thus obtain agility, a bias voltage is applied. The simulated results are compared with measured data, and good agreement is obtained.

Tunable properties of light propagation in photonic liquid crystal fibers

2006 ◽  
Vol 14 (4) ◽  
Author(s):  
K. Szaniawska ◽  
T. Nasilowski ◽  
T. Woliński ◽  
H. Thienpont
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Light Propagation ◽  
Solid Core ◽  
Simulation Methods ◽  
Pure Silica ◽  
Tunable Properties ◽  
Crystal Fibers ◽  
Propagation Properties ◽  
Good Agreement

AbstractTunable properties of light propagation in photonic crystal fibers filled with liquid crystals, called photonic liquid crystal fibers (PLCFs) are presented. The propagation properties of PLCFs strongly depend on contrast between refractive indices of the solid core (pure silica glass) and liquid crystals (LCs) filing the holes of the fiber. Due to relatively strong thermo-optical effect, we can change the refractive index of the LC by changing its temperature. Numerical analysis of light propagation in PLCF, based on two simulation methods, such as finite difference (FD) and multipole method (MM) is presented. The numerical results obtained are in good agreement with our earlier experimental results presented elsewhere [1].

Rectilinear low-frequency shear of homogeneously aligned nematic liquid crystals

1993 ◽  
Vol 441 (1913) ◽  
pp. 559-573 ◽  
Keyword(s):  
Thin Film ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Theoretical Analysis ◽  
Low Frequency ◽  
The Other ◽  
Critical Amplitude ◽  
Linear Shear ◽  
Theoretical Results ◽  
Good Agreement

A thin film of nematic liquid crystal (ZLI 1085) is sandwiched between two horizontally mounted glass blocks, whose faces have been treated to align the molecules of the liquid parallel to the plane of the blocks. By moving one block relative to the other in its own plane, the liquid crystal is subjected to an oscillatory linear shear. Above a certain frequency-dependent amplitude, mechanical Williams domains of alternating bright and dark stripes are observed perpendicular to the direction of shear. A theoretical analysis of this phenomenon is carried out to provide predictions for both the thickness of the stripes and the critical amplitude as a function of frequency. Good agreement is found between the experimental and theoretical results.

scholarly journals Ion-Generating and Ion-Capturing Nanomaterials in Liquid Crystals

Proceedings ◽  
2018 ◽  
Vol 2 (14) ◽  
pp. 1122
Author(s):  
Yuriy Garbovskiy
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Fields ◽  
Future Research ◽  
Research Directions ◽  
Liquid Crystal Devices ◽  
Proposed Model ◽  
Future Research Directions ◽  
Practical Implications ◽  
Good Agreement

The majority of tunable liquid crystal devices are driven by electric fields. The performance of such devices can be altered by the presence of small amounts of ions in liquid crystals. Therefore, the understanding of possible sources of ions in liquid crystal materials is very critical to a broad range of existing and future applications employing liquid crystals. Recently, nanomaterials in liquid crystals have emerged as a hot research topic, promising for its implementation in the design of wearable and tunable liquid crystal devices. An analysis of published results revealed that nanodopants in liquid crystals can act as either ion-capturing agents or ion-generating objects. In this presentation, a recently developed model of contaminated nanomaterials is analyzed. Nanoparticle-enabled ion capturing and ion generation regimes in liquid crystals are discussed within the framework of the proposed model. This model is in very good agreement with existing experimental results. Practical implications and future research directions are also discussed.

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.

scholarly journals Transition Temperatures of Thermotropic Liquid Crystals from the Local Binary Gray Level Cooccurrence Matrix

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
S. Sreehari Sastry ◽  
T. Vindhya Kumari ◽  
C. Nageswara Rao ◽  
K. Mallika ◽  
S. Lakshminarayana ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscope ◽  
Gray Level ◽  
Transition Temperatures ◽  
Statistical Parameters ◽  
Thermotropic Liquid Crystals ◽  
Phase Transition Temperatures ◽  
Good Agreement

This paper presents a method which combines the statistical analysis with texture structural analysis called Local Binary Gray Level Cooccurrence Matrix (LBGLCM) to investigate the phase transition temperatures of thermotropicp,n-alkyloxy benzoic acid (nOBA,n=4,6,8,10and 12) liquid crystals. Textures of the homeotropically aligned liquid crystal compounds are recorded as a function of temperature using polarizing optical microscope attached to the hot stage and high resolution camera. In this method, second-order statistical parameters (contrast, energy, homogeneity, and correlation) are extracted from the LBGLCM of the textures. The changes associatedwiththe values of extracted parameters as a function of temperature are a helpful process to identify the phases and phase transition temperatures of the samples. Results obtained from this method have validity and are in good agreement with the literature.

New structure induced by elastic anisotropy in cylindrical nematic liquid crystal

2017 ◽  
Vol 13 (2) ◽  
pp. 4705-4717
Author(s):  
Zhang Qian ◽  
Zhou Xuan ◽  
Zhang Zhidong
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystal ◽  
Elastic Anisotropy ◽  
Nematic Liquid Crystals ◽  
Gennes Theory

Basing on Landau–de Gennes theory, this study investigated the chiral configurations of nematic liquid crystals confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls. When the elastic anisotropy (L2/L1) is large enough, a new structure results from the convergence of two opposite escape directions of the heterochiral twist and escape radial (TER) configurations. The new defect presents when L2/L1≥7 and disappears when L2/L1<7. The new structure possesses a heterochiral hyperbolic defect at the center and two homochiral radial defects on both sides. The two radial defects show different chiralities.

scholarly journals Liquid Crystal Devices for Beam Steering Applications

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 247
Author(s):  
Rowan Morris ◽  
Cliff Jones ◽  
Mamatha Nagaraj
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Adaptive Optics ◽  
Beam Steering ◽  
Optical Components ◽  
Advantages And Disadvantages ◽  
Liquid Crystal Devices

Liquid crystals are valuable materials for applications in beam steering devices. In this paper, an overview of the use of liquid crystals in the field of adaptive optics specifically for beam steering and lensing devices is presented. The paper introduces the properties of liquid crystals that have made them useful in this field followed by a more detailed discussion of specific liquid crystal devices that act as switchable optical components of refractive and diffractive types. The relative advantages and disadvantages of the different devices and techniques are summarised.

scholarly journals Optical Response Associated with the Orientation and Structure of Liquid Crystals with Respect to Phosphatidylcholine Concentration

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 678
Author(s):  
Yuqi Han ◽  
Yan Jiang ◽  
Wei Guo ◽  
Bing Li ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Reflectance Spectrum ◽  
Optical Response ◽  
The Self ◽  
Cholesteric Liquid Crystals ◽  
Anchoring Effect ◽  
Self Assembling ◽  
Sensitization Effect ◽  
Structure Of Liquid

Based on the anchoring effect due to the self-assembling behavior of the phospholipid molecules at the interface between the liquid crystal and water phases on the orientation of liquid crystals, the optical response associated with the orientation and structure of liquid crystals with respect to the concentration of 1,2-didodecanoyl-sn-glycero-3-phosphocholine solution has been investigated. The optical response owing to changes in the orientation and structure of the mixed cholesteric liquid crystals with respect to the change in the concentration of phosphatidylcholine has been obtained. Moreover, the feasibility of using as-prepared mixed cholesteric liquid crystals to measure the phosphatidylcholine concentration has been verified. A methodology to measure the reflectance spectrum by using mixed cholesteric liquid crystals to sensitize the phosphatidylcholine concentration has been further realized. The sensitization effect of the mixed cholesteric liquid crystals on the measurement of phosphatidylcholine concentration was also verified.

scholarly journals Optofluidic Platform Based on Liquid Crystals in X-Cut Lithium Niobate: Thresholdless All-Optical Response

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 908
Author(s):  
Fabrizio Ciciulla ◽  
Annamaria Zaltron ◽  
Riccardo Zamboni ◽  
Cinzia Sada ◽  
Francesco Simoni ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Light Intensity ◽  
Lithium Niobate ◽  
Photovoltaic Effect ◽  
Optical Control ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Threshold Behaviour ◽  
All Optical

In this study, we present a new configuration of the recently reported optofluidic platform exploiting liquid crystals reorientation in lithium niobate channels. In order to avoid the threshold behaviour observed in the optical control of the device, we propose microchannels realized in a x-cut crystal closed by a z-cut crystal on the top. In this way, the light-induced photovoltaic field is not uniform inside the liquid crystal layer and therefore the conditions for a thresholdless reorientation are realized. We performed simulations of the photovoltaic effect based on the well assessed model for Lithium Niobate, showing that not uniform orientation and value of the field should be expected inside the microchannel. In agreement with the re-orientational properties of nematic liquid crystals, experimental data confirm the expected thresholdless behaviour. The observed liquid crystal response exhibits two different regimes and the response time shows an unusual dependence on light intensity, both features indicating the presence of additional photo-induced fields appearing above a light intensity of 107 W/m2.

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