A5027241232- Liquid Crystal Research Advancements
- Advanced Antenna and Metasurface Technologies
- Microwave Engineering and Waveguides
- Antenna Design and Analysis
- Nonlinear Dynamics and Pattern Formation
- Advanced Materials and Mechanics
- Surfactants and Colloidal Systems
- Semiconductor Lasers and Optical Devices
- Molecular spectroscopy and chirality
- Advanced Optical Imaging Technologies
- Photonic Crystals and Applications
- Photochemistry and Electron Transfer Studies
- Advanced MRI Techniques and Applications
- Electrowetting and Microfluidic Technologies
- Surface Roughness and Optical Measurements
- NMR spectroscopy and applications
- Synthesis and Properties of Aromatic Compounds
- Lanthanide and Transition Metal Complexes
- Optical and Acousto-Optic Technologies
- Image and Video Quality Assessment
- X-ray Diffraction in Crystallography
- Silicon and Solar Cell Technologies
- Antenna Design and Optimization
- Electrical and Thermal Properties of Materials
- Material Dynamics and Properties
Merck (Germany)
2006-2024
Christoffel Blinden Mission
2024
Merck & Co., Inc., Rahway, NJ, USA (United States)
2006
Crystal Consulting (Germany)
2003
We report a liquid crystal 1 that shows ferroelectricity at room temperature. directly enters the ferroelectric nematic phase from isotropic upon cooling, without formation of conventional phase. The synthesis, microscopic texture observations and dielectric spectroscopy measurement results are presented. A relative permittivity over 20000 is observed in Together with its low melting point new will accelerate application research device prototyping various directions.
Abstract We present a new ferroelectric nematic material, 4-((4′-((trans)-5-ethyloxan-2-yl)-2′,3,5,6′-tetrafluoro-[1,1′-biphenyl]-4-yl)difluoromethoxy)-2,6-difluorobenzonitrile (AUUQU-2-N) and its higher homologues, the molecular structures of which include fluorinated building blocks, an oxane ring, terminal cyano group, all contributing to large dipole moment about 12.5 D. observed that AUUQU-2-N has three distinct liquid crystal phases, two were found be polar phases with spontaneous...
We report the smectic $A_F$, a new liquid crystal phase of ferroelectric nematic realm. The $A_F$ is small polar, rod-shaped molecules which form two-dimensional fluid layers spaced by approximately mean molecular length. uniaxial, with director, local average long-axis orientation, normal to layer planes, and ferroelectric, spontaneous electric polarization parallel director. Polarization measurements indicate almost complete polar ordering $\sim 10$ Debye longitudinal dipoles, hysteretic...
We demonstrate an exceptional ability of a high-polarization 3D ferroelectric liquid to form freely suspended fluid fibers at room temperature. Unlike threads in modulated smectics and columnar phases, where translational order is prerequisite for forming fibers, recently discovered nematic forms with solely orientational molecular order. Additional stabilization mechanisms based on the polar nature mesophase are required this. propose model such mechanism show that these nonlinear optical...
In ferroelectric nematics, strong splay rigidity can be attributed to the electrostatic self-interaction of polarisation, avoiding polarisation splay.
A tunable phase shifter using liquid crystal (LC) is presented. The device fabricated in a fashion similar to LC displays which makes fabrication very simple compared, for example, MEMS approaches. At the targeted operation frequency of 20 GHz offers performance above 60° differential shift per dB insertion loss and minimum tuning speed 340 ms.
Novel approaches of tunable devices for millimeter wave applications based on liquid crystal (LC) are presented. In the first part paper, a novel concept LC phase shifter realized in Low Temperature Cofired Ceramics technology is shown while second paper deals with high-gain antenna an reflectarray. The reflectarray features continuously beam scanning between<mml:math...
The optical birefringence (Δ n ) and dielectric anisotropy ε of nematic liquid crystals were calculated using the well-known theories Vuks Maier-Meier, respectively. molecular dipole moments polarizabilities needed for estimation taken from semiempirical AM1 calculations. values are in good agreement with experimental results investigated compounds having different core structures polar substituents.
In this paper a novel transmission line topology partially filled with liquid crystal is investigated in terms of its usability as high performance continuously tunable phase shifter. At first the special properties crystals are described briefly. Then theoretical results based on developed simulation tool discussed order to explain advantages waveguide structure compared other techniques. Experimental confirm expected by showing an excellent Figure-of-Merit Ka-band region.
Liquid crystal mixtures dedicated to microwave application have been developed. They high tuning ranges, low dielectric losses and reliability against the heat stress. These help realize agile LC-based components devices, such as phase shifter, tunable filter, phased array- or reflect array antennas.
A tunable resonator based on change of substrate permittivity is fabricated using a new high performance liquid crystal GT3-23001. The results show measured frequency tuning range 8.2% compared with simulated 8.5% around centre 2.8 GHz, lower insertion loss to standard crystals.
A tunable substrate-integrated waveguide phase shifter using low-temperature co-fired ceramic (LTCC)-technology is presented in this paper. By changing the effective permittivity liquid crystal (LC)-filled waveguide, differential can be tuned continuously. This achieved by means of an analog signal applied to electrodes, surrounding LC. The design allows for precise tuning phase, which proven with a Monte Carlo measurement resulting errors less than 3° at 28 GHz. Besides that, ambient...
The complex dielectric constant of 4- n -pentyl-4 ′ -cyanobiphenyl (5CB) was measured between 0.0001 Hz and 1 kHz in nematic isotropic phases. Dielectric relaxation due to space-charge polarization observed for both In the phase, diffusion coefficient D ⊥ mobility µ ions 5CB were determined by theoretical analysis frequency dependence constant. ∥ estimated an extrapolation procedure utilizing a magnetic field. activation energies calculated accordance with Arrhenius plots; furthermore,...
This paper presents investigations conducted with tunable reflectarray unit cells based on nematic liquid crystals (LC), at frequencies around 77 GHz. The structure of the is presented, as well their performance measured in a waveguide simulator setup. Encouraging results phase ranges high 280° tuning voltages up to 15V have been achieved. investigated will be used electronically reconfigurable reflectarrays.
The performance of a Rotman lens, which forms fixed beams at 0°, ±15° and ±30°, is augmented using liquid crystal phase shifters to simultaneously steer each beam by up ±7.5°. Measured results are used demonstrate that the true time delay property antenna voltage controlled can be exploited provide continuously scanned with full coverage over an angular range ±37.5°, operation band 6–10 GHz.
This paper investigates the realization of reconfigurable reflectarrays based on tunable liquid crystals (LC). Two different concepts unit cells using highly anisotropic LC have been designed and measured, showing good results possibility employing them in a full-scale reflectarray. A 16 times fixed beam microstrip reflectarray has developed order to verify feeding concept. Good agreement is obtained between simulation measurement
The distribution of the local electric field in a liquid-crystal cell containing mobile ions was simulated accordance with Poisson equation steady state under DC voltage application. determined to be markedly unbiased due contribution bound charges on electrodes induced by ions. This result suggests that intensity acting can approximated external field, for analyzing space-charge polarization small AC application even very low frequency region, where diffusion distance during period becomes...
This paper describes the development of a liquid crystal (LC) controlled waveguide filter demonstrator for space application. The can be used in satellite input multiplexer section (IMUX) and allows shifting frequency from 19.7...20.2 GHz with 200 MHz bandwidth. magnetically or electrically. electrical field is generated by dedicated LTCC electrodes.
Low Temperature Cofired Ceramic (LTCC) is used as a substrate material for microelectronic devices in satellite communication. Its dielectric properties and excellent variability allows good compactness high level of integration. An LTCC antenna array microwave signals operating at 30 GHz presented. All components such radio frequency distribution network, four waveguide phase shifters horn antennas are integrated one ceramic module. The implemented volume cavities the LTCC. A tailored...
ABSTRACT An electronically reconfigurable Rotman lens is described which generates multiple beams that can be switched from monopulse sum to difference radiation patterns when used in conjunction with a six element Vivaldi antenna array. This achieved by exploiting the voltage‐dependent dielectric anisotropy property of nematic state liquid crystals provide 0° and 180° phase shifts array feed lines. The viability concept demonstrated designing an exhibits dynamically over frequency band 6–10...
Abstract A significant reduction of the power consumption a liquid crystal display can be achieved either by application lower driving voltage or – even more effectively use holographically structured reflective scattering type without colour filters. The first option requires strongly polar materials with extremely high reliability, second one new types crystals birefringence as possible in order to optimize effect. molecular modeling based method for prediction reliability parameters is presented.
Abstract Liquid crystal (LC) materials with features of coexistence high birefringence and low rotational‐viscosity were developed, by introducing novel class tolane substances. Those LC mixtures exhibit voltage‐holding‐ratio enough for active matrix addressing, their excellent physical properties improve the TN‐mode display performances significantly. The extremely fast switching characteristics enable TN panels to be applicable field sequential color displays.