This PDF file contains the front matter associated with SPIE Proceedings Volume 10735, including the Title Page, Copyright information, Table of Contents, Author listing, and Conference Committee listing.

Owing to its excellent elasticity, wide spectral range of transparency, and outstanding chemical and thermal stability, polydimethylsiloxane (PDMS) is an elastomer of great technological importance, being widely used in the fabrication of microfluidic and optofluidic devices in particular. Compact, low loss optical waveguides are crucial in such devices for a dense integration of optical functionalities. Compared with photolithographic methods, multiphoton laser direct writing through photopolymerization has shown great promise in the fabrication of three-dimensional (3D) optical waveguides in PDMS without the limit of planar structures. Here we demonstrate a multiphoton laser direct writing process that produces low-loss, ultra-compact waveguides in PDMS. The fabrication employs a self-initiated multiphoton polymerization of phenylacetylene infused in PDMS without additional photoinitiator. The elimination of the photoinitiator results in an excellent refractive index homogeneity and thus a low propagation loss due to scattering, as well as a greater biocompatibility by involving the fewest possible chemicals (monomer only) in the polymerization reaction. Our characterizations show that the waveguides fabricated as such are on average 1.3 µm wide with a refractive index contrast of 0.06 and a propagation loss of 0.03 dB/cm in the spectral band of 650-700 nm. Our technique will enable a broad range of applications spanning from wearable photonics to chip-scale optical interconnects.

A colossal optical nonlinearity has been observed for the dye-doped liquid crystals under the condition that the nematic phase is very close to the isotropic condition, and it has been usually explained by the effect of the dye-induced torque on the liquid crystal. However, the direct observation of the photo-response by the time-resolved transient grating phase imaging revealed that the optical nonlinear polarization, causing the extraordinary refractive index change, was observed in the liquid crystal region, where the light was not irradiated. Furthermore, a shock-like wave was observed after this nonlinear response ended. We propose that a compression wave generated at the disordered/ordered interface induced the reorientation of liquid crystal molecules to generate a larger polarization, causing the optical nonlinearity.

Controlled formation of surface topographies has led to an interesting set of applications (friction control, cell adhesion and motility, self-cleaning and many more). Utilizing light-sensitive molecules in combination with liquid crystal network (LCN) coatings allows for the creation of surface structures upon irradiation. For these LCN coatings, the alignment determines the shape of the topography and thus the application of the material. An outstanding method to control the alignment of the liquid crystals locally, is utilizing a so-called photo-alignment layer. Here, we present the use of such a layer in combination with azobenzene-doped LCN coatings to create different shapes of topographies that can be used for oscillatory deformations. Azobenzene-doped LCN coatings were made with different planar alignments and defect lines. Upon UV light actuation, we obtained asymmetric or symmetric topographies defined by the symmetry of the defect. In this way we create asymptotic, hills, valleys or continuous sinusoidal topographies. In addition we show that these topographies can be addressed locally. We induced these oscillatory deformations by utilizing polarized UV light in combination with blue light to control the cis and trans formation of the azobenzene crosslinker. Since the azobenzene has dichroic properties, this illumination method induces a local actuation of the azo-LCN coating. Upon rotation of linear polarized UV light, the actuation becomes oscillatory and the surface structures dynamic.

Liquid crystals (LCs) have been suggested to have a place in biological sensing for detection and quantitation of biomolecules. Through many years, texture observation has long been the core technique in LC-based bioassays. Its principle stems from the texture change of LCs due to the interruption of the initially homeotropic alignment in nematic bulks or the radial-to-bipolar configuration transition in LC droplets in the presence of biomolecules. Biodetection through optical texture observation is convenient but remains a qualitative method, and alternative approaches of detection and quantitative analysis are necessary for the development of a practical LC-based biosensor. In this study, we explore the potential of two dye-enhanced LCs, a dye LC (DLC) and a dye-doped LC (DDLC), in biosensing and protein quantitation. Depending on the chromophore or dye incorporated in DLC and DDLC, the dichroic features of these LCs enable us to analyze the change in their orientation in the presence of biomolecules by transmission spectrometry, from which spectral parameters are derived to establish novel LC-based protein quantitative methods.

Cellular membrane separates the cytosol from the extracellular space and contains the molecules that facilitate transmission of life-sustaining signals exhibiting lateral heterogeneity through the compartmentalization of lipids, proteins, and carbohydrate molecules. Micro-domains of cholesterol and sphingolipid-rich membranes, called lipid rafts, have attracted much attention from their critical roles in cellular processes through the structural organization and the regulation of protein activation, signaling, and pathogenesis/treatment of neurological and psychiatric disorders. Using supported lipid membranes on wedge-shape substrates with alternating positive and negative curvatures, we represent the curvature-mediated asymmetry of lipid raft domains across the membrane leaflets accompanied by glycolipid receptor localization such as GM1 and GT1b. The raft domains initially appear only in membrane leaflets possessing negative curvature. In the presence of the inter-leaflet coupling, they evolve to generate the transverse registry across the membrane bilayer. We show that a human recombinant anti-body rHIgM12, known to be therapeutic in a mouse model of a neurologic disease, is co-localized with the rafts formed at the peaks and valleys of the wedge substrate, indicating that the spatial distribution of its receptor (GT1b) is indeed manifested by the site-specific formation of asymmetric raft domains through the curvature elasticity. Our methodological platform is a powerful tool of clarifying the mechanism for the leaflet asymmetry and lipid sorting in terms of the membrane curvature, the composition, and the receptor presentation.

The carapace of insects can generate optical information with vivid structural colors, which may be of paramount importance in the life and the evolution of most day-living animals. A cholesteric liquid crystal organization of chitin fibrils is recurrently at the origin of optical properties. We summarize some recent results on the carapace of scarab beetles with possible functions related to optical information and thermoregulation. In the case of Chrysina gloriosa, green bands include wavelength-selective micromirrors and silver stripes play the role of flat metallic reflector operating over the visible spectrum and into the NIR-IR spectrum. Bio-inspired materials might address broadband reflectors for energy savings, stealthiness, cryptography or wavelength-specific light modulators in routing technologies.

Azobenzene-based complex dyes (PAAD) have found many applications, in particular in liquid crystal based waveplates and flat lenses [1-2]. We investigated PAAD layers, both as individual thin films and as an alignment layer in liquid crystal waveplates, for modulating and steering laser beams. Thin (15-35 nm), stand-alone films of PAAD, illuminated by an interference fringe pattern, show considerable photo-sensitivity, in spite of limited thickness. We exploited this effect to record polarization patterns and observed considerable diffraction efficiency, with gratings formed through the refractive index change rather than surface relief. Diffraction efficiency depended strongly on the relative polarization of the pump versus the probe beam. The ratio between diffraction efficiencies in the two polarization states reached two orders of magnitude. These measurements were used to carry out preliminary modelling to investigate grating formation and optical axis distribution in the PAAD layer, thus opening the possibility of using optical measurements to study the PAAD thin film molecular dynamics. We also developed an optically controlled, half-wave plate based on a twisted nematic liquid crystal cell with a single PAAD alignment layer. The cell was bistable, with the two states controlled by one-step illumination of with visible light. The photo-alignment properties of the layer led to reversible switching between two perpendicular alignment states at the cell surface, resulting in controllable polarization manipulation. Reproducible modulation of the transmitted polarization with an optical contrast of up to 90-100% was achieved for different wavelengths of the probe beam, from visible to near infrared.

Liquid crystals have been used in displays, spatial light modulators, various phase/polarization modulators and lenses. In most lens applications, where a continuous variability is needed, the refractive lens approaches (particularly the gradient index (GRIN)) are privileged. However, this approach is limiting the achievable optical power variability range for application requiring larger clear aperture diameters (ophthalmic, augmented reality, etc.). We shall describe two new approaches allowing the further increase of that diameter while still keeping the optical quality of the lens as high. Those approaches are based on the addition of a control electrode and its dynamic control. The presentation will focus on design aspects, but the corresponding application requirements will be discussed also.

Debate on the origin of chirality has lasted for several centuries. Lots of theories in different fields have been propounded to illustrate the possible sources. However, there were no convincing proofs could be provided. In this work, through constructing the relationship between aggregation and chirality, a significant insight was brought to explain how the chirality was generated from the achiral system. Besides, aggregation-induced circular dichroism (AICD) effect was discovered in some AIEgens decorated with amino acid or sugars and aggregation-annihilated circular dichroism (AACD) effect was reported in axially chiral systems. In AICD systems, it was proved that the chirality could transfer from chiral centers to AIEgens in the aggregate state but not solution. Meanwhile, it was concluded that the right-handed helical structures corresponded to a negative Cotton effect and vice versa. For the AACD effect, further studies suggested that the annihilation was caused by the change of twist angle within the process of aggregation.

Liquid crystalline cholesteric blue phases (BPs) are of high interest for tunable electro-optic applications owing to their fast response times and quasi-polarization-independent phase modulation capabilities. Various approaches have recently been proposed to control the crystal orientation of BPs on substrates, but their basic orientation properties on standard, unidirectionally orienting substrates had not been investigated in detail. Here, detailed studies have been made on the Kossel diagrams of BPs on unidirectionally orienting substrates to understand the three-dimensional crystal orientation of BPs. We find that BPs show strong thermal hysteresis and that the structure of the preceding phase determines the orientation of BPs. Specifically, the BP II – I transition is accompanied by a rotation of the crystal such that the crystal direction defined by certain low-value Miller indices transform into different directions, and within the allowed rotations, different azimuthal configurations are obtained in the same cell depending on the thermal process. Our findings demonstrate that, for the alignment control of BPs, the thermal process is as important as the properties of the alignment layer.

Optical pattern formation is usually due either to the combination of diffraction and nonlinearity in a Kerr medium or the temporal modulation of light in a photosensitive chemical reaction. We present a different mechanism by which light spontaneously induces stripe domains between nematic states in a twisted nematic liquid crystal layer doped with azo-dyes. Due to the photoisomerization process of the dopants, light creates dissipative structures without the need of temporal modulation, diffraction, Kerr or other optical nonlinearity, but based on the different scales for dopant transport processes and nematic order parameter, which identifies a Turing mechanism for this instability. Theoretically, the emergence of the stripe patterns is described by a model for the dopant concentration coupled with the nematic order parameter.

Graphene, a monoatomically thick film made by carbon atoms arranged in honeycomb lattice, for its exceptional electrical, thermal and mechanical properties is one of the most attractive materials to be incorporated in electronic devices and in composites. New interest has been recently arisen from water suspensions of flakes of graphene oxide (GO), obtained from chemical exfoliation of graphite, since they form liquid crystal (LC) phases, for the easiness of handling graphene, otherwise forming aggregates, and their high yield. Interestingly, GO LC suspensions are responsive to electric fields with an extremely high Kerr coefficient resulting in an induced birefringence at macroscopic scale, achieved with very low electric fields. The LC phase formation and its responsiveness to electric fields are dependent on suspension characteristics such as flake average dimension, aqueous matrix and flake properties. In particular, bare graphene flakes have larger response to electric fields, due to their higher polarizability, than GO flakes. As it will be described, this results in improved electro-optic performance of reduced-graphene compared to GO LC with remarkably higher optical transmission for the same field strength thanks to a more efficient flake reorientation enabling a larger optical modulation.

Heating, ventilation, and air conditioning of buildings account for about 15% of the global energy consumption, but about 20% of this building-related energy is lost because of inefficient windows. Is there a solution to this challenging problem? Starting from an overview of the physical principles associated with energy loss through windows, I will describe our development of visibly transparent, infrared-reflecting, thermally super-insulating and mechanically robust materials that may replace or retrofit the inefficient windowpanes of residential and commercial buildings. I will discuss how this technology has much in common with liquid crystal displays and how production of such unusual transparent aerogel materials is aided by bacteria to make them affordable.

Optical and dielectric anisotropies of nematic liquid crystals are key properties in controlling light transmission when implemented with polarizers. On the other hand, optical metamaterial is artificial nano-structure composed of subwavelength inclusions permitting a variety of new optical functions. Combination of nematics with optical metamaterial leads to an optical device structure where transmission and reflection can be controlled by optical and electrical means. By constructing an optical metamaterial with optical anisotropy, nematics permits electric control of reflection and transmission. When V-shaped nano-antennas are introduced, anomalous refraction can also be electrically controlled by employing nematics. Rapid phase change of a light beam in a phase-discontinuity optical metamaterial leads to a strong deflection of beam path allowing observation of optical spin Hall effect. When nematics are placed in the beam path, post-selection in weak measurement can be electrically tuned, which allow an electric control of optical spin Hall transverse shift in optical metamaterial. Furthermore, a thin film of organics is shown to be a new epsilon-near-zero metamaterial. Molecular structure possessing a strong coupling between two neighboring excitons shows an epsilon-near-zero response, owing to superposition of large numbers of Lorentzian oscillators in a narrow spectral range.

Chromatic aberrations of diffractive waveplate optics for imaging applications can be corrected for different switchable states. Different opportunities for lenses and prisms, and their limitations are discussed.

Liquid crystal (LC) devices have been used for smart window and see-through display applications. Especially, LC devices which can be used to control the haze value have been studied for smart window applications. LC devices with the polymer structure, such as polymer-dispersed and polymer-stabilized LC cells, can be used to control the haze value. However, for wider applications, it is urgent to overcome disadvantages, such as the high operating voltage, low transmittance in the transparent state, and narrow viewing angle because of the index mismatch between the LC and polymer structure. In this paper, we introduce LC devices based on the electro-hydrodynamic effect. They can provide a high haze in the translucent state because of the turbulence caused by the electro-hydrodynamic effect. They can provide a high transmittance in the transparent state and wide viewing angle because it does not contain any polymer structure. We believe that LC devices based on the electro-hydrodynamic effect can be an excellent candidate for smart window applications.

In the past three decades, the volume of global data traffic has been growing at an astonishing rate with little sign to slow down. In responding to this need, the backbone of the network for long distance data communication has evolved from all electrical based on copper wires or radio, mixed optical and electrical with optical fibers in data transportation and electronics in switches and end-nodes, to all optical in which information is kept in the optical domain throughout the network until it reaches its final destination. To make use of the vast bandwidth available, concurrency among multiple channels of optical transmission is necessary, and the wavelength division multiplexing (WDM) is the main technique in use. A wavelength selective switch (WSS) is able to route selectively individual WDM channels of any formats entering its input fibre port to any of the output fibre ports according to the optical configuration controlled via software by the service providers. Phase-only liquid crystal on silicon (LCOS) spatial light modulator (SLM) is currently the most flexible optical engine for WSSs, one of the key enabling technologies for software defined reconfigurable all optical networks. We will review the advantages of LCOS WSSs and the use of holographic wavefront modulation for advanced switching functionalities and delivery of the key performance matrix. We will then introduce a new stacked WSS architecture based on 2D beam steering, where multiple independent WSSs can be integrated on a single LCOS device with common optics. This approach can significantly reduce the cost, footprint and power consumption and allow the WSSs to be reconfigured as ultra-high port count switches or non-blocking wavelength cross-connects (WXCs). Finally, we will address how this stacked WSS architecture can be utilized to meet the optical switching demand in large-scale data centres.

The photorefractive effect of smectic liquid crystal blends containing small amount of chiral compound was investigated. The photorefractive ferroelectric liquid crystal blends are known to exhibit a large photorefractive effect. They are composed of Smectic-C liquid crystals, photoconductive chiral compounds and a sensitizer. Smectic liquid crystal blends that contains several concentrations of a chiral compound while keeping a constant concentration of a photoconductive moiety were prepared. The effect of the concentration of the chiral dopant on the photorefractive properties of the liquid crystal blend was investigated.

"Ferroelectric smectic (SmC) phase" Anchoring effects on the polymer films in the liquid crystal (LC) display devices plays key role to create the restoring force to the black state for any types of display modes, such as IPS, STN, VA and OCB etc. On the contrary, we have designed the slippery interfaces in the homeotropic ferroelectric (SmC*) liquid crystals for the DH-FLC mode as walls wetted on the electrodes in the in-plane switching cell, and success to reduce the driving voltage keeping the ultra-fast response. "Principle & Design" We have invented the new principle to produce the slippery interfaces on the glass plates or even nano-interfaces embedded in the materials such as PSChBP. Slippery interfaces are created by the disorder effect induced by the several types of frustration. For example, the impurities with surface affinity weaken or melt the liquid crystalline (LC) order near the interfaces, then boundary region of LC spontaneously play roles on the slippery interfaces. Therefore, the anchoring effect disappears, and molecular motion is lubricated by the slippery interfaces. Especially, change of the anchoring to the slippery condition can be controlled by UV illumination on localized azo dye surfaces. "Evaluation" We measure the dynamics of surface director rotation under rotating magnetic field, and analyze the response of the surface director by changing the strength of the magnetic field and rotation speed of the cell. Therefore, we correctly evaluate the change of the anchoring condition which is related to the anchoring energy and viscosity of surface director. Anchoring phenomena is strongly dependent on the model of the slippery interface, the temperature and even the LC materials on the interface.

The ability to reversibly photo-pattern an infinite variety of high-quality, high-resolution alignment domain orientations and shapes makes photoswitchable LC devices ideal candidates for laser applications where electro-optical spatial-light modulators cannot be used due to their low laser-damage resistance (typically, 230 mJ/cm2 at 2.4 ns, 5 Hz at 1053 nm). Such all-optical devices also have the advantage of their inherent simplicity (no electrical interconnects or driver electronics) and convenient in-system write/erase capability. Azobenzene-based photoswitchable alignment materials are excellent candidates for such devices by virtue of their high laser damage thresholds at 1053 nm, which range from 24-66 J/cm2 (1.4 ns pulse). In this work, LC devices fabricated with commercial azobenzene photoalignment layers were exposed to a series of varying optical patterns that were sequentially written, erased and re-written into the assembled devices using either contact photolithography with a xenon/mercury high-pressure arc lamp source or a 433 nm diode laser. These devices were capable of being written, erased and re-written in excess of 30 times without showing significant image burn-in or loss of patterning resolution. Amplitude beam shaping of a 500 mW Nd;YLF 1053 nm laser beam in a laboratory bench-top setup was demonstrated using photoswitchable LC devices in which the beam-shaping profile had been written using the 433 nm diode laser setup and photolithography mask in a bench-top image relaying setup. Similar optical patterning experiments conducted on a series of new photoalignment materials synthesized in-house have shown one example in which written optical patterns have remained stable for more than 4 months under ambient conditions.

Organic semiconductors show promise in the development of a new age of electronics that are inexpensive, flexible, wearable, and bio-compatable. A great amount of work has been done to engineer and characterize new organic semiconductors in organic thin film transistors (OTFTs), resulting in charge carrier mobility values greater than 10cm2/Vs. The performances of these devices still fall well short of their silicon counterparts mostly due to molecular morphology, grain size, and carrier concentration. One solution to these problems is to use the intrinsic order found in liquid crystal (LC) mesophases. Previous work shows that [1]benzothieno[3,2-b][1]benzothiophene (BTBT) can be used to produce high-performing OFTFs. This is due large in part to the paramorphic SmE to crystal transition commonly seen in these materials that induces long-range molecular order within the crystal structure. In this work, we synthesized and characterized single-tailed BTBT molecules that contain a paramorphic SmE to crystal transition in single-step solution-processed OTFTs. Further, the addition of a pentafluorobenzene thiol (PFBT) self-assembled monolayer (SAM) to the gold electrodes improved charge injection, reducing the device threshold voltage and increasing the on/off ratio. It is suspected that the molecular packing is responsible for high mobility values. Future work will aim to explore the use of host-guest chemistry doping and LC alignment techniques to further improve carrier concentration and charge transfer properties to improve bulk material transport properties.

Patterning the surface alignment in liquid crystal devices is a highly effective strategy to realize additional functionalities to the liquid crystal electro-optic devices. One example is a switchable diffractive optical device that utilizes polarization/phase grating structures imprinted on the alignment surface. When it is working in the Pancharatnam-Berry phase mode, it is possible to realize a perfect beam diffraction without the loss of energy into higher order diffractions. In order to apply this attractive technology to a practical device, a drawback often encountered is the low throughput of the fabrication of such fine patterns with a spatial resolution comparable to the light wavelength, irrespective of the fabrication techniques employed. The purpose of this presentation is to describe an efficient scheme for fabricating fine polarization patterns over a large area based on the unique property of the Pancharatnam-Berry phase itself. We refer this scheme as “recursive photoalignment,” since the photoaligned pattern is used as the photomask for the subsequent photoalignment step; each step of photoalignment in this way allows us to prepare an enlarged pattern by a linear factor of 2, while maintaining the pattern resolution always the same as the original pattern. We demonstrated the feasibility of this technique by fabricating a 50mmX50mm photoalignment pattern with a finest resolution of a few micrometers, starting from a 2mmX2mm master pattern fabricated by a DMD-based maskless photoalignment processor. Although there are certain limitations on the type of pattern for this method to work, it also opens up a new opportunity to synthesize large area-fine resolution patterns from a less technically demanding photoalignment pattern.

In this paper, we present a new photoswitchable viscoelastic material with liquid crystalline natures, which exhibits two types of nematic liquid crystalline phases and a crystal phase beneath the isotropic liquid. We present its light-triggered phase behaviors and photo-switchability of the viscoelastic properties.

It was discovered recently that liquid crystal dimers with a flexible central linkage with an odd number of carbons, such as CB7CB, have bent molecular shapes and have anomalously small bend elastic constants. When such a dimer is doped into regular liquid crystals, it can greatly modify the properties of the hosts and can enable novel structures and electro-optical properties. We doped CB7CB to a regular thermotropic nematic liquid crystal and then dispersed the material in isotropic polymer with tangential anchoring condition, we obtained toroidal liquid crystal droplets, which was only realized before for lyotropic liquid crystals. When we doped CB7CB to a regular cholesteric liquid crystal, we obtained perfect planar state without any oily streak defects. Also by doping CB7CB to a cholesteric liquid crystal, we achieved stable Helfrich deformation and reflection color tuning under low driving voltages.

Liquid crystal phase boundaries play an important role in self-assembly processes defining nanostructured complex fluid systems. Surface boundary conditions, director- dependent surface tension and topological defects produce elastic forces that combine to define the architecture of multiphasic anisotropic fluids. Developing a detailed understanding of these forces is necessary for a first principals understanding of anisotropic biological structures and producing the next generation of mesoscopic materials. We will discuss our recent experimental progress on thermotropic LC and colloidal LC consisting of cellulose nanocrystals and graphite.

A prior simulation-only study of aspherical phase profiles [Hornburg et al, Proc SPIE 10743, 10743-4 (2018)] in geometric-phase lenses (GPLs) indicated that aspherical doublet lens systems should provide substantially improved off-axis performance than those using spherical phase profiles. In this work, we fabricate a liquid crystal GPL doublet (24.5 mm diameter, 40 mm back focal length at 633 nm) and compare it to with a reference spherical GPL singlet. We characterized the liquid crystal alignment quality, efficiencies, and spot performance. With these compact GP lens systems, we realize improved performance for wider fields of view, while maintaining low loss.

Optically addressed spatial light modulators (OASLM) are promising for holographic applications and optical limiters. Self-activated OASLMs can operate as autonomous energy devices, opening the route to stand-alone laser protection devices and smart windows. They are mainly based on liquid crystal (LC) devices, integrated with inorganic photovoltaic substrates such as LiNbO₃:Fe or dye-sensitized TiO₂. While robust, they also suffer from several restrictions such as high costs, low performances and/or small device area.

In this work, we propose a new type of an autonomous modulator. Blends of electron-donating (D) conjugated polymers and electron-accepting (A) fullerene molecules were used as a photovoltaic thin films and integrated into liquid crystal device. Such D/A bulk heterojunctions are the major building block of solution-processed organic solar cells and are known to convert incident light into electrical energy. In our case, the organic layer generates a photovoltaic field that is used to control the LC alignment under illumination. We carried out cross-polarized intensity measurements on this photovoltaic-LC device to demonstrate the expected occurrence of a light–dependent birefringence change, without an applied voltage. In this way, by combining solution-processed organic photovoltaic thin films with optical responsive liquid crystals, our work paves the way to low cost and large area self-sustained optical devices.

Liquid crystal materials have interesting properties in Terahertz wave range. Specially 0.3 – 10.0 range is interesting looking from application point of view. The structure and rotational and vibrational oscillations of liquid crystal molecules have influence on physical properties of the material in this frequency range. Chosen liquid crystal materials with dielectric anisotropy parameters (Δε form 0 to more than 30) and optical refractive index (Δn from 0 to about 0.6) in THz range ware investigated. Firstly transmission, absorption and permittivity of chosen liquid crystal molecules were simulate. Influence ofdifferent terminal group like F, CN, NCS and quantity of benzene rings were compared. Relations between structure of molecules and absorption spectra were observed. These parameters were compared with experimental data. Some liquid crystal materials (single compounds and mixtures) obtained in Institute of Chemistry MUT with very high polarization coefficients more that 2000 nC/cm2 and relatively low loss were tested. Significant differences in their dielectric losses and dichroism have been obtained. Refractive indices and absorption parameters were characterized. Acceptable dynamic parameters from application point of view were received. This kind of liquid crystal samples can have application in tunable terahertz devices, like tunable phase shifter and gratings.

In this paper, electro-optical properties of sandwich-like cells utilizing polymers (either weakly conducting or ferroelectric) and nematic liquid crystals are reported. The tuning of the threshold voltage for electrically controlled birefringence is demonstrated. Physical mechanisms of this tuning are discussed.

Transmittance-control devices, such as a suspended particle device, electrochromic device, and dye-doped liquid crystal (LC) device, have been studied for a smart window, eyewear, and automotive applications. These devices require a high transmittance difference between the transparent and opaque states. Among the dye-doped LC devices, a dye-doped chiral-nematic LC (CNLC) cell has been widely used for transmittance-control devices. However, the colors of cells are different between the homogeneously aligned and CNLC cell. In this study, we demonstrated a systematic approach to find optimum dye concentrations for black color in a dye-doped CNLC cell. We took its transmission spectrum into account in the numerical calculation to realize the black color in a dye-doped CNLC cell. Through the iterative method, we could optimize the concentration of each single dye for realizing the black color. We confirmed that a dye-doped CNLC cell designed by considering transmission spectrum of it could provide the black color in the CIE 1931 color space.