Liquid Crystal Alignment Effects Research Articles

Dielectric Meta-Atoms with Liquid Crystal Alignment Effect for Electrically Tunable Metasurface

Dielectric metasurfaces with tunable functions are increasingly appealing to both the academia and industrial communities. Among the many tuning mechanisms reported so far, metasurface immersed in liquid crystal (LC) stands out as one of the most viable approaches for industrial applications such as Lidar and 3D sensing. However, as with traditional LC devices, alignment processes are necessary for LC-based tunable metasurfaces, leading to additional costs in terms of time and materials. In this paper, we present a novel LC-based tunable metasurface, wherein the alignment of LC is provided by the metasurface structures. LC serves as the dielectric environment for the metasurface with an electrically tunable refractive index. Simultaneously, purposely engineered metasurface induces alignment effects within the LC. The alignment effect of the metasurface on the LC was quantitatively characterized using crossed polarizers. A marked transmission contrast was observed, indicating the high-quality alignment provided solely by the metasurface. Electrical tunability was also measured, recording a maximum modulation depth in transmission amplitude of 94% at near-infrared telecommunication wavelengths. This work highlights the remarkable advantages of LC-based tunable metasurface devices, making them highly valuable for next-generation metasurface-integrated LC on silicon devices.

Liquid crystal alignment effect and electro-optical characteristics of rubbing-atmospheric plasma coprocessing in ZnO alignment film according to concentration

Liquid crystal alignment effect and electro-optical characteristics of rubbing-atmospheric plasma coprocessing in ZnO alignment film according to concentration

THz Nematic Liquid Crystal Devices Using Stacked Membrane Film Layers

Twisted nematic type THz polarization control devices using liquid crystal immersed membrane films were fabricated by using simple stacking process. First of all, we verify the liquid crystal alignment effect in various kinds of membrane films. From THz Time-Domain Spectroscopy measurements, apparent refractive index anisotropy was observed in liquid crystal immersed Polytetrafluoroethylene and Polyolefin membrane films. Furthermore, transmission properties of twisted nematic type THz device are in rough agreement with 4 × 4 matrix calculation data. We believe that primary characteristic of THz TN device can be obtained by optimizing the fabrication processes and measurement method.

Multi-Dimensional Liquid Crystal Alignment Effect of Polymer Wall on Vertically Aligned Liquid Crystal Cell

This paper investigates the multi-dimensional liquid crystal (LC) alignment effect of a polymer wall. The polymer wall is formed on the pixel boundary by an anisotropic phase separation method, which affects the nearby LC orientation. Vertically aligned (VA) LC cells are fabricated in order to show the effect of the polymer wall on LC displays. The electro-optic characteristics of the LC cell are affected by the shape and orientation of the molecules that form the polymer wall. The VA LC cell that has a polymer wall formed by vertically-aligned anisotropic-molecules on the pixel boundary shows much faster turn-on and turn-off times than the conventional LC cell without polymer wall, as well as no loss of transmittance within its pixel area.

Liquid Crystal Alignment Effects on SiNx Thin Film Layers Treated by Ion-Beam Irradiation

Nematic liquid crystal (NLC) alignment effects on SiNx thin film layers treated by ion-beam irradiation for three types of N ratio were successfully studied for the first time. The SiNx thin film was deposited by plasma-enhanced chemical vapor deposition using three types of N ratio. To characterize the film, atomic force microscopy was performed. Good LC aligning capabilities on the SiNx thin film treated by ion-beam irradiation for all N ratios can be achieved. The low pretilt angle for an NLC on the SiNx thin film treated by ion-beam irradiation was observed and could be adopted in planar alignment liquid crystal display applications as in-plane switching and fringe-field switching modes.

Liquid Crystal Alignment Effects for Nematic Liquid Crystal on Homeotropic Polyimide Surface Using New Ion-Beam Source

We have studied the liquid crystal (LC) alignment and tilt angle generation of a nematic liquid crystal (NLC) on a homeotropic polyimide (PI) surface using a new ion beam source. The tilt angle of the NLC on the homeotropic PI surface for all incident angles is about 38° and this angle has a stabilization trend. A good LC alignment of the NLC on the homeotropic PI surface by to exposure ion beam of 45° incidence angle was observed. Also, the tilt angle of the NLC on the homeotropic PI surface by to exposure ion beam of 45° incidence angle had a tendency to decrease as ion beam energy density increased. Thus, we demonstrated that the tilt angle could be controlled from vertical to horizontal directions. Also, the alignment character of the NLC on the homeotropic PI surface with respect to ion beam energy was good at more than 1500 eV. Finally, a superior LC alignment thermal stability on the homeotropic PI surface subject to ion beam exposure was achieved.

Liquid Crystal Alignment Effects on Nitrogen-doped Diamond like Carbon Layer by Ion Beam Alignment Method

We have studied the nematic liquid crystal (NLC) alignment effects on a nitrogen-doped diamond-like carbon (NDLC) thin film layer with ion beam irradiation. The pretilt angle for NLC on the NDLC surface with ion beam exposure was observed below 1 degree. Also, we had the good LC alignment characteristics on the NDLC thin films with ion beam exposure of 1800 eV. In thermal stability experiments, the alignment defect of the NLC on the NDLC surface with ion beam irradiation above annealing temperature of can be observed. Therefore, the good thermal stability and LC alignment for NLC by ion beam aligned NDLC thin films can be achieved.

Homeotropic Alignment Effect for Nematic Liquid Crystal on the SiOxThin Film Layer by New Ion Beam Exposure

We studied homeotropic alignment effect for a nematic liquid crystal (NLC) on the <TEX>$SiO_{x}$</TEX> thin film irradiated by the new ion beam method. <TEX>$SiO_{x}$</TEX> thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) and were treated by the DuoPIGatron ion source. A uniform liquid crystal alignment effect was achieved over 2100 eV ion beam energy. Tilt angle were about <TEX>$90^{\circ}$</TEX> and were not affected by various ion beam energy.

LC Alignment Effects and EO Performances for Homeotropic Aligned NLC on the SiOx Thin Film Layer by e-Beam Evaporation

In this study, liquid crystal (LC) alignment effects for homeotropic alignment on the SiOx thin film by electron beam evaporation method with electron beam system and electro-optical (EO) performances of homeotropic aligned liquid crystal display (LCD) were studied. Also, the control of pretilt angles of homeotropic aligned LC on SiOx thin film as a function of thin film thickness were investigated. The uniform vertical LC alignment on the SiOx thin film surfaces with electron beam evaporation was achieved in any of the thin film thickness conditions. It is considered that the LC alignment on the SiOx thin film by electron beam evaporation is attributed to the elastic interaction between LC molecules and micro-grooves at the SiOx thin film surface created by evaporation. In addition, LC cell of the SiOx thin film by electron beam evaporation had good EO property.

Liquid Crystal Alignment Effects Using a-C:H Thin Films Deposited at RF Bias Condition

The nematic liquid crystal (NLC) aligning capabilities using a-C:H thin film deposited at the three kinds of rf bias condition were investigated. A high pretilt angle of about 11° by the ion beam alignment method was observed on the a-C:H thin film (polymer-like carbon) deposited at 1 W rf bias condition, and the low pretilt angle the NLC than 1 W rf bias conditions was observed on the a-C:H thin film (diamond-like carbon) deposited at rf 30 W and 60 W bias condition. Consequently, the high LC pretilt angle and the good aligning capabilities of LC alignment by the ion beam alignment method on the a-C:H thin film deposited at 1 W rf bisa condition can be achieved. Also, the good thermal stability of LC alignment by the IB alignment method on the a-C:H thin film as working gas at rf bias condition can be achieved.

Diamond-Like-Carbon 박막표면에 UV 배향법을 이용한 액정 배향 효과에 관한 연구

Diamond-Like-Carbon 박막표면에 UV 배향법을 이용한 액정 배향 효과에 관한 연구

N-(phenyl)maleimide 단독 중합체 광폴리머를 이용한 액정 배향 효과

N-(phenyl)maleimide 단독 중합체 광폴리머를 이용한 액정 배향 효과

Liquid Crystal Alignment Effects on the Photo-Crosslinkable Copolymer Surfaces Containing Cholesteryl Moiety

Pretilt angle generation for a nematic liquid crystal (NLC) and electro-optical (EO) performances of the vertical-alignment (VA)-liquid crystal display (LCD) photoaligned with obliquely polarized UV exposure on the three kinds of copoly (M4Ch-ChMA), copoly ((4-methacryloyloxy) chalcone - cholesteryl methacrylate) surfaces for homeotropic LC alignment were studied. The NLC pretilt angle of 81° was observed with UV exposure of 3 min on the photo-crosslinkable copolymer surface. The NLCs pretilt angle is attributable to increased chalcone with increasing the UV exposure time. Also, a good voltage-transmittance (V-T) curve and fast response time in the VA-LCD photoaligned with obliquely polarized UV exposure of 30 ° on the photo-crosslinkable copolymer surfaces can be achieved.

Liquid Crystal Alignment Effects on the Photo-Crosslinkable Copolymer Surfaces Containing Cholesteryl Moiety

Pretilt angle generation for a nematic liquid crystal (NLC) and electro-optical (EO) performances of the vertical-alignment (VA)-liquid crystal display (LCD) photoaligned with obliquely polarized UV exposure on the three kinds of copoly (M4Ch-ChMA), copoly ((4-methacryloyloxy) chalcone - cholesteryl methacrylate) surfaces for homeotropic LC alignment were studied. The NLC pretilt angle of 81° was observed with UV exposure of 3 min on the photo-crosslinkable copolymer surface. The NLCs pretilt angle is attributable to increased chalcone with increasing the UV exposure time. Also, a good voltage-transmittance (V-T) curve and fast response time in the VA-LCD photoaligned with obliquely polarized UV exposure of 30 ° on the photo-crosslinkable copolymer surfaces can be achieved.

Atomic force microscopy characterization and liquid crystal aligning effect of polymerizable diacetylene Langmuir Blodgett films

Abstract The surface topology of polymerizable diacetylenic lecithin Langmuir Blodgett (LB) films deposited on indium-tin oxide (ITO) coated glass substrates has been investigated using atomic force microscopic (AFM) techniques. The liquid crystal alignment effect of the LB films was compared to that of the random film formed by dipping the ITO glass into chloroform-lecithin solution. The orientation of a nematic monodomain based on these substrates was changed from homeotropic to tilted upon ultraviolet (UV) irradiation, and a planar alignment was achieved if the substrates were UV treated and buffed. AFM pictures reveal that the substrate surface corrugation is decreased by both random coating and LB film coating before photopolymerization. After UV irradiation, some unique star-like features were found on the monolayer LB film. These features provide evidence that the conformation of the diacetylene chains has been changed due to the photopolymerization, thus causing the liquid crystal orientation to undergo a transition from homeotropic to tilted alignment.