scholarly journals Influences of Central Units and Terminal Chains on the Banana-Shaped Liquid Crystals

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 857
Author(s):  
Tang Xin Ting ◽  
Mohd Sani Sarjadi ◽  
Md Lutfor Rahman
Keyword(s):  
Liquid Crystals ◽  
Data Storage ◽  
Smart Materials ◽  
Optical Data Storage ◽  
Optical Data ◽  
Display Devices ◽  
Functionalized Materials ◽  
Potential Applications ◽  
The Impact ◽  
Photoisomerization Process

Azo-functionalized materials are one of the appealing groups of the functionalized materials owing to their photoswitching behaviour and have been explored for various potential applications viz., optical data storage, sensor, display devices, nonlinear materials and molecular switches. Recently, azo-functionalized bent-core liquid crystals (BCLCs) have gained significant attention because they have dual properties of BCLCs and azobenzene, which enables to generate new multifaceted functional and smart materials. In this report, the recently synthesized azobenzene containing bent-core mesogens and its subclass, the so-called hockey stick and V-shaped molecules are summarized. The mesomorphic behaviour of reported BCLCs affected by the type of central core unit, the nature, number and position of the lateral substituents and the type and length of the terminal chain are discussed. The photoisomerization process of these photoresponsive BCLCs in solid, solution and mesophase, as well as the impact of light on the chemical and electrical properties of them, are discussed.

Recent Progress of Electro-optic Polymers for Device Applications

1997 ◽  
Vol 488 ◽  
Author(s):  
Alex K-Y. Jen ◽  
Qing Yang ◽  
Seth R. Marder ◽  
Larry R. Dalton ◽  
Ching-Fong Shu
Keyword(s):  
Data Storage ◽  
High Speed ◽  
Stable State ◽  
Optical Data Storage ◽  
Device Fabrication ◽  
Optical Data ◽  
Material System ◽  
Electro Optic ◽  
Potential Applications ◽  
Device Applications

AbstractElectro-optic (E-O) polymers have drawn great interest in recent years because of their potential applications in photonics devices such as high speed modulators and switches, optical data storage and information processing1–2. In order to have suitable materials for device fabrication, it is essential to design and develop polymeric material systems (active and passive polymers) with matched refractive indices, large E-O coefficients, good temporal and photochemical stability3–8 The E-O response of an active polymer commonly arises from the electric field induced alignment of its second-order nonlinear optical (NLO) chromophore, either doped as a guest/host system or covalently bonded as a side-chain. Because of the strong interaction among the electric dipoles, the poled structure is in a meta-stable state; the poled NLO chromophores which possess large dipole moment will tend to relax back to the randomly oriented state. As a result, the stability of the poled structure strongly depends on the rigidity of the overall material system. As it might be expected, the continuous increases of the rigidity and Tg of poled polymers imposes constraints on the selection of suitable chromophores that can survive the hightemperature poling and processing conditions. To circumvent this problem, we have developed a series of chromophores that possess conformation-locked geometry and perfluoro-dicyanovinylsubstituted electron-accepting group which demonstrate both good thermal stabilty and nonlinearity. This paper provides a brief review of these highly efficient and thermally stable chromophores and polymers for device applications.

New glassy liquid crystals for optical data-storage applications

1995 ◽  
Vol 61 (1) ◽  
pp. 59-62 ◽  
Author(s):  
H. J. Eichler ◽  
R. Elschner ◽  
G. Heppke ◽  
R. Macdonald ◽  
H. Schmid
Keyword(s):  
Liquid Crystals ◽  
Data Storage ◽  
Optical Data Storage ◽  
Optical Data ◽  
Glassy Liquid Crystals

Liquid crystals for holographic optical data storage

2007 ◽  
Vol 36 (12) ◽  
pp. 1868 ◽  
Author(s):  
Avtar S. Matharu ◽  
Shehzad Jeeva ◽  
P. S. Ramanujam
Keyword(s):  
Liquid Crystals ◽  
Data Storage ◽  
Optical Data Storage ◽  
Optical Data

In-Situ Tem Study of Crystallisation of Amorphous SbOx Films

1995 ◽  
Vol 404 ◽  
Author(s):  
R. Nayak ◽  
A. K. Petford-Long ◽  
R. C. Doole ◽  
C. N. Afonso
Keyword(s):  
Data Storage ◽  
Laser Pulses ◽  
Optical Data Storage ◽  
Optical Data ◽  
In Situ Tem ◽  
Video Tape ◽  
Random Nucleation ◽  
Video Frames ◽  
Potential Applications

AbstractAmorphous d.c. sputtered SbOx films (0.19< x<2.0) have been found to be fast crystallising materials sensitive to nano- and pico-second laser pulses, and have potential applications as optical data-storage media. They were crystallised in-situ in a JEOL 4000EX TEM, and the crystallisation recorded onto video tape. The crystallisation of the SbO0.37 films occurred by random nucleation followed by growth until coalescence. In contrast the crystallisation of the SbO0.533 films occurred by surface crystallisation across the whole film followed by bulk crystallisation through the film, during which contrast in the TEM increased steadily. Analysing the video frames in an image processing package enabled kinetic parameters such as transformation index and activation energy to be extracted. High resolution transmission electron microscopy showed the crystalline phase to contain nano-crystallites approximately 10 nm in size in a less-ordered matrix.

ChemInform Abstract: Liquid Crystals for Holographic Optical Data Storage

ChemInform ◽  
2008 ◽  
Vol 39 (8) ◽  
Author(s):  
Avtar S. Matharu ◽  
Shehzad Jeeva ◽  
P. S. Ramanujam
Keyword(s):  
Liquid Crystals ◽  
Data Storage ◽  
Optical Data Storage ◽  
Optical Data

Upconversion Luminescence Behaviour of Er3+/Yb3+ Doped MY2O4 (M=Ba, Ca, Sr) Phosphors

2018 ◽  
pp. 117-148
Author(s):  
Vikas Dubey ◽  
Neha Dubey ◽  
Ravi Shrivastava ◽  
Jagjeet KaurSaluja ◽  
Sudipta Som ◽  
...  
Keyword(s):  
Rare Earth ◽  
Data Storage ◽  
Upconversion Luminescence ◽  
Optical Transmittance ◽  
Optical Data Storage ◽  
Optical Data ◽  
High Optical Transmittance ◽  
Potential Applications ◽  
Rare Earth Doped ◽  
Upconversion Process

The upconversion (UC) of the rare earth doped MY2O4 (M=Ba, Sr, Ca) has been extensively investigated due to their potential applications in many fields, such as color display, high density memories, optical data storage, sensor and energy solar cell, etc. Many series of them, especially the Er3+, Yb3+ doped MY2O4 were studied in this chapter, due to the thermal and mechanical toughness, high optical transmittance from the ultraviolet to the infrared regions, and a low nonlinear refractive index compared to the other commercial laser glasses. The energy transfer (ET) mechanism of rare earth doped phosphor plays an important role in the upconversion process.

scholarly journals Photochromism in a New Light: Temperature-Dependent in situ Photocrystallography

2014 ◽  
Vol 70 (a1) ◽  
pp. C767-C767
Author(s):  
Jordan Cox ◽  
Ian Walton ◽  
Dinesh Patel ◽  
Mengyang Xu ◽  
Andrea Markelz ◽  
...  
Keyword(s):  
Data Storage ◽  
Computational Models ◽  
Incident Light ◽  
Anomalous Behavior ◽  
Optical Data Storage ◽  
Optical Data ◽  
Temperature Dependent ◽  
Photochromic Molecules ◽  
Potential Applications

Organic photochromic molecules including diarylethenes are of particular interest for their potential applications in fields of high density optical data storage and light-activated switches, among many others. However, one of the limitations in diarylethene-based systems has been the low photoconversion observed in neat single crystals which is often less than 20%. The low conversion is typically believed to be the result of screening effects in which the photoisomerized molecules at the surface absorb incident light preventing full isomerization of the crystal. To assess the effect of screening on a model diarylethene system, photocrystallographic experiments on microcrystals of the compound were performed using synchrotron radiation at the Advanced Photon Source at Argonne National Labs. During the course of the study, we discovered that the photoconversion of the diarylethene crystals exhibits highly unusual temperature dependent behavior which is incongruent with current computational models of diarylethene photochemistry. Herein we report the first temperature-dependent `constant irradiation' in situ photocrystallography experiments performed on a photochromic system. Through the application of this technique, combined with spectroscopic analysis, we demonstrate that the steady-state population arising from the photo-cyclization reaction shows a temperature dependence which has been heretofore unobserved. Possible explanations for this anomalous behavior and its role in the photochemical reactivity of this and other diarylethene systems will be presented.

The Microstructural Response of a Multilayer Thin Film to Local Laser Heating

1989 ◽  
Vol 152 ◽  
Author(s):  
Matthew R. Libera ◽  
Martin Chen ◽  
Kurt A. Rubin
Keyword(s):  
Data Storage ◽  
Laser Heating ◽  
Pulsed Laser ◽  
Optical Data Storage ◽  
Optical Data ◽  
Maximum Temperature ◽  
Additional Layer ◽  
Forming Temperature ◽  
Chalcogenide Layer ◽  
The Impact

ABSTRACTThe microstructures associated with pulsed-laser heating of multilayer thin films used for phase-change optical data storage are studied in three related films. Two employ the multilayer structure SiOx/TeGeSn/SiOx where the chalcogenide layer is either amorphous or crystalline. The third uses the same trilayer structure with a crystalline chalcogenide layer but with an additional layer of aluminum. Pulsed-laser melting of micron-sized spots leads to solidification in the non-aluminized specimens with a morphology dependent on the preexisting structure of the chalcogenide layer and to amorphization in the aluminized film. Heat-flow modelling shows that the maximum temperature reached is lower and the cooling rate through the glass-forming temperature range higher in the aluminized structure. Discussion centers on the thermal and optical properties of the different films and the impact of the pre-existing chalcogenide structure on the subsequent phase transformations.

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