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Metasurfaces garner widespread attention for their remarkable ability to precisely manipulate light and construct optical multiplexing devices. However, there is still a lack of effective solutions for achieving high‐performance wavelength decoupling in the realm of wavelength multiplexing. In this work, a novel wavelength decoupling method based on minimalist metasurfaces featuring a single‐celled configuration is proposed. These metasurfaces are composed of only two types of nanobricks, each capable of modulating the phase of two different wavelengths simultaneously as desired. The proposed minimalist metasurfaces possess the advantages of flexible design, enabling wavelength decoupling with incidences at both co‐ and cross‐polarization states. Interestingly, by integrating the wavelength decoupling metasurface with liquid crystal devices, information encryption can be achieved. The proposed wavelength decoupling method holds broad application prospects in the fields of optical data storage, image display, information security, and beyond. [ABSTRACT FROM AUTHOR]

Liquid crystals have been applied to light modulation devices by taking advantage of their prominent feature of electro-optical response. The modulation contains the amplitude (intensity) modulation and the phase modulation. The most common device of the intensity modulation is a liquid crystal display. On the other hand, devices that apply the phase modulation function have also been attracting attention in the market in recent years. However, the operating principle of phase modulation devices is difficult to understand because the concept of phase is less familiar than that of intensity. Taking up a simple light beam steerer using liquid crystal as an example of the phase modulator, this paper explains its operating principle through numerical simulation. [ABSTRACT FROM AUTHOR]

The present work was the preliminary study of phase diagrams and miscibilities of low-temperature metallomesogen (MOM) model structures based on rod-like palladium (Pd) alkyl/alkoxy-azobenzene metal complexes and their mixtures with commercial liquid crystal materials for potential application. The initial results indicated the accessible temperature range and mesgenic miscibility between parent ligand, MOMs and commercial liquid crystal mixtures. The eutectic ligand/MOM composition with other MOMs and commercial nematic liquid crystal materials exhibited complete mesogenic miscibility and wide low-temperature mesogenic stability for eventual utilization in commercial liquid crystal devices. [ABSTRACT FROM AUTHOR]

Optics has advanced through centuries of research into the fundamental properties of light and its interactions with matter. Within this rich history, one optical component stands out: the diffraction grating. Liquid crystals (LCs) have emerged as promising candidates in diffraction gratings. LCs are versatile and adaptable materials influenced by various external factors. Diffractive LC grating devices can be produced through methods such as photo alignment, using polymer walls, or employing patterned electrodes. However, photo alignment poses challenges in terms of manufacturing complexity, and using polymer walls is associated with some drawbacks, such as high driving voltage and slower response times, which must be considered in their application. Currently, research efforts are predominantly focused on manufacturing techniques involving patterned electrodes. In this review, we comprehensively explored the theoretical foundations underpinning diffraction gratings. Additionally, we summarized research on diffractive gratings based on LC using patterned electrodes and conducted a comparative analysis of the characteristics of each device. [ABSTRACT FROM AUTHOR]

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Herein, we propose a brush‐coated zirconium‐doped lanthanum oxide (ZrLaO) film as a liquid crystal (LC) alignment layer. The film‐curing temperature was adjusted to 70, 150, and 230°C. Polarized optical microscopy and pre‐tilt angle analysis confirmed that there was uniform and homogeneous LC alignment on the 230°C cured ZrLaO film. Atomic force microscopy revealed that the surface had a nano/microgroove structure, which was caused by the shear stress generated by the brush‐coating process. This structure induced the uniform LC alignment. X‐ray photoelectron spectroscopy verified that the ZrLaO film was well‐formed on a glass substrate. The ZrLaO film displayed hydrophilic characteristics, and its surface energy increased as the film‐curing temperature increased. The ZrLaO alignment layer displayed suitable optical transmittance for LC device applications. The ZrLaO layer‐based twisted‐nematic LC cell exhibited more stable switching properties and better threshold voltage characteristics than conventional polyimide layers. Therefore, we expect that this brush‐coated ZrLaO layer will be a suitable LC alignment layer for LC device applications. [ABSTRACT FROM AUTHOR]

A novel material‐constrained method for the design of liquid crystal optical devices – computer‐generated liquid crystal‐based holograms – and their manufacture using photo‐patterning is demonstrated. The developed topology optimization method is compared to the Gerchberg‐Saxton algorithm, and key advantages and disadvantages are outlined. The key novelties and advantages of the method are that it accounts for the natural relaxation and material properties of the liquid crystal and that it can account for different material or manufacturing constraints, such as maximum optical axis gradients. The viability of the method is applied for different binary and greyscale target images of varying complexity, target image sizes, and algorithms that account for the material properties of the liquid crystal. Finally, with the topology optimization design approach and photo‐patterning, it is possible to produce high‐accuracy and high‐contrast liquid crystal‐based computer‐generated holograms. [ABSTRACT FROM AUTHOR]

Spatiotemporal structured light has opened up new avenues for optics and photonics. Current spatiotemporal manipulation of light mostly relies on phase-only devices such as liquid crystal spatial light modulators to generate spatiotemporal optical fields with unique photonic properties. However, simultaneous manipulation of both amplitude and phase of the complex field for the spatiotemporal light is still lacking, limiting the diversity and richness of achievable photonic properties. In this work, a simple and versatile spatiotemporal holographic method that can arbitrarily sculpt the spatiotemporal light is presented. The capabilities of this simple yet powerful method are demonstrated through the generation of fundamental and higher-order spatiotemporal Bessel wavepackets, spatiotemporal crystal-like and quasi-crystal-like structures, and spatiotemporal flat-top wavepackets. Fully customizable spatiotemporal wavepackets will find broader application in investigating the dynamics of spatiotemporal fields and interactions between ultrafast spatiotemporal pulses and matters, unveiling previously hidden light-matter interactions and unlocking breakthroughs in photonics and beyond. The authors showcase a spatiotemporal holographic method that can arbitrarily sculpt spatiotemporal light by generating various spatiotemporal wavepackets. The ability to deploy these fully customizable wavepackets opens up exciting avenues for their use in broader applications. [ABSTRACT FROM AUTHOR]

Liquid crystal devices have been in practical use for more than half a century and are now widely used as low-voltage, low-power-consumption displays and optical elements. We have confirmed the partial NOT logic operation of some optical interference peaks in two-slit Young's interference experiments using a liquid crystal device with a self-aligned structure. In this report, we report that we were able to obtain a fully NOT logic operation of the entire optical interference pattern by investigating the liquid crystal alignment of antiparallel direction. [ABSTRACT FROM AUTHOR]

In this paper, we study the influence of the protein Bovine Serum Albumin (BSA) on the dielectric properties of liquid crystals (LCs) such as 4-cyano-4-pentyl biphenyl (5CB) and Octyl-4-biphenylcarbonitrile (8CB). Studying the effect of proteins on the dielectric properties of LC is essential for both fundamental research and practical applications in material science, biomedical engineering, biotechnology, and optoelectronic devices. It helps understand the protein behaviour on the surface of LCs, which offers an opportunity to develop novel sensing platforms. A polarising optical microscope (POM) was used to examine the correlation between textures formed by LCs interacting with different concentrations of BSA. In the dielectric studies, dielectric parameters such as impedance (Z), real (Z') and imaginary (Z") parts of the impedance, and the tangential loss (tan δ) were measured. The investigation involved analysing relaxation times using the collected data, revealing distinct behaviours between 5CB and 8CB liquid crystals. Bode and Nyquist's plots were constructed and analysed to investigate the changes LCs undergo while interacting with BSA. An equivalent electrical circuit (EEC) was constructed using Bode and Nyquist data, from which circuit element values were successfully extracted. The results obtained from the POM studies and the interferences drawn from the EIS can help enhance the performance of protein-based liquid crystal devices. [ABSTRACT FROM AUTHOR]

For liquid crystal display‐based devices, the memory sub‐system and backlight consume a notable amount of energy, posing a critical concern, especially for portable devices. This work introduces an integrated display system (IDS) aimed at combining technologies for energy‐efficient memory usage and backlight power optimization, which have been addressed independently until now in the existing literature. Two modifications of approximated memory are proposed to find an optimal scheme for energy‐efficient memory usage as part of the proposed IDS schemes. Additionally, three distinct IDS schemes are proposed and compared to identify an optimum solution, ensuring energy efficiency maximization while maintaining image quality for each image. Experimental results demonstrate that 42.19% of energy consumption in memory access and 37.57% of the backlight power consumption can be reduced, while maintaining the image quality in terms of two different metrics. [ABSTRACT FROM AUTHOR]

This article presents the theoretical study, numerical simulation and fabrication of a phase shifter and a stub resonator for use in microstrip ridge gap waveguide (MRGW) technology, using a liquid crystal (LC) in the substrate as a reconfigurable material. The phase shifter and the stub resonator are filled with LC, and thanks to the LC's dielectric anisotropy properties, the phase shift and the resonance response can be easily controlled using an external electric or magnetic bias field. The phase shifter was designed to operate in the range of 10 to 20 GHz, and the resonator was designed to operate in the range of 7.8 to 8.8 GHz. The phase shifter's responses (including both phase shift and insertion losses), associated with both the parallel and perpendicular permittivity values of the LC, were computed and measured, and then the corresponding figure of merit (FoM) was extracted. The resonator's frequency responses, associated with both the LC's parallel and perpendicular permittivity, were computed. The resonator's frequency responses, which provided different polarization voltages, were measured and compared to the simulation results. All technological issues related to both prototypes are also discussed here. The good agreement between the simulation and measurement results confirm this technology as a viable approach to the practical implementation of these microwave reconfigurable devices. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the use of two-photon polymerization direct laser writing in the production of continuously tuneable optical vortex beam (OV) generators in a liquid crystal (LC) layer sandwiched between glass substrates. Results are presented that show how an OV generator can be inscribed into a 20 μm-thick LC layer and how the order of the OV beam can be tuned with the application of a voltage. Importantly, only a single pair of electrodes is needed to tune the order of the vortex as the required phase profile is generated through the 3D structuring of the polymer network using the laser writing process. Following the design and fabrication of the LC-OV generator, a Mach–Zehnder interferometer is subsequently employed, in conjunction with polarizing optical microscopy, to characterize the devices to confirm the generation of OVs of different orders and to determine the corresponding chirality. The paper concludes by considering whether these LC-OV generators can function at a range of different operation wavelengths. Such devices would be of potential importance in applications ranging from optical communications to quantum physics. [ABSTRACT FROM AUTHOR]

Liquid crystals are widely used in photonics because of their profound electro–optic properties. However, the slow switching speeds (milliseconds) and the fluid nature of liquid crystals restrict their potential use in integrated photonics. In this work, polymer‐stabilized liquid crystals are utilized as the functional material to improve the response time with a polymer network that helps pre‐orientate the liquid crystal. Additionally, plasmonic slot structures are simultaneously employed to minimize the switch voltage by confining the optical field within the electrode spacing at subwavelength scales. Thanks to the large overlap of the optical and electric fields, the scattering states of the polymer‐stabilized liquid crystal can be effectively manipulated to modulate the loss of the propagating wave, resulting in strong optical attenuation in the integrated photonic platform. Specifically, a plasmonic enhanced polymer‐stabilized liquid crystal photonic device for operation at 1550 nm, which has a length of only 10 µm and shows an extinction ratio of 0.38 dB µm−1, with a power consumption of less than 6 µW and a response time ≈20 µs, resulting in a figure‐of‐merit of 0.012 mW. [ABSTRACT FROM AUTHOR]

Wavelength‐tuneable lasers can play a crucial role across many fields, and their applications continue to expand with advancements. Cholesteric liquid crystal (CLC) devices are developed, enabling good wavelength‐tuneable lasers. In CLC devices, pitch control is required to tune the desired wavelength. However, pitch control takes a long time and is difficult, which limits the speed and range of laser wavelength tuning. Here, by applying a voltage once and forming an electric field gradient along the wedge direction in the CLC wedge cell, we could realize CLC pitch gradient arrays that achieve continuous wavelength tuning over 500 nm in only 10 min through the electrothermal effect while continuously generating laser lines in the full visible spectrum. The laser wavelength could be rapidly tuned over the full visible spectrum by moving within the array in the wedge cell. The study of CLC cells for electric field application in real time is able to observe the dynamic process of pitch change directly. This new laser device and strategy has potential in many fields that require active laser tuning and is expected to lead to innovative changes in the development of future practical laser devices in the optical industry. [ABSTRACT FROM AUTHOR]

We review recent research in various types of optical quantum computing using liquid crystal devices. First, we have investigated Young's Interference experiment using self-aligned liquid crystal (LC) devices and a logical "NOT" operation is achieved. Second, numerical quantization of interfering small photons using an LC retarder is investigated. Third, a Mach–Zehnder interferometer with an optical phase control by a twisted nematic (TN) LC device was studied. Fourth, a basic experiment on 2-bit quantum calculations related to the Deutsch-Jozsa algorithm on a linear optical quantum computer using the LC device as a linear optical element was investigated. [ABSTRACT FROM AUTHOR]

Due to the limitation of materials, PIC cannot achieve large magnitude phase modulation in a small size, and lacks the reconfigurable ability. Because of its birefringence characteristic, liquid crystal can be used in the liquid crystal on silicon (LCoS) device to achieve a large amount of phase modulation in a small size and has the capacity of reconstruction. Based on the experimental results of LCoS devices and basic liquid crystal waveguide devices, the liquid crystal waveguide device is prepared. While retaining the LCoS spatial optical phase modulation capability, the liquid crystal waveguide and phase modulation capability are realized. The beam splitter, optical switch, and Mach–Zehnder interferometer structure are constructed, which verifies the feasibility of the liquid crystal waveguide phase modulator. [ABSTRACT FROM AUTHOR]

The polarization‐independent liquid crystal (LC) phase modulators can greatly improve the efficiency and reduce the complexity of the optical system. However, it is difficult for the LC phase modulator to achieve both good low‐loss modulation and polarization‐independent properties. A LC phase modulator of single layer multi‐microdomain orthogonal twisted (MMOT) structure is proposed which may achieve good polarization independence and low loss in different phase depth. A lightcontrolled azimuth angle (LCAA) process based on the rotation effect of cholesteric liquid crystal (CLC) is developed for the fabrication of the single layer MMOT structure. The measurement results showed that the single layer MMOT LC phase modulator may get very low polarization dependence, about 3.52% under 2Ï€ phase modulation depth, with low loss. The device shows good potential application in optical communication, wearable device, and display. [ABSTRACT FROM AUTHOR]

The fringe field effect in liquid crystal (LC) devices can cause pixel crosstalk issues. Therefore, LC devices with multiple electrode structures require multiple calibrations to achieve an approximate distribution of the target phase modulation. At the same time, optical inverse design based on data‐driven algorithms is also a highly popular topic. This article introduces a deep‐learning approach to realize inverse phase modulation in LC devices. By adopting the deep learning method for inverse phase modulation in LC devices, can effectively alleviate the problems caused by fringe field effects and achieve more precise and accurate phase modulation distribution. [ABSTRACT FROM AUTHOR]

PDLC films, synthesized via polymerization-induced phase separation (PIPS) utilizing both temperature and UV monochromatic radiation, were derived from a blend of E7 nematic liquid crystal (LC) and PolyEGDMA875 (polyethyleneglycoldimethacrylate) oligomers, serving as the precursor for the polymeric matrix. The influence of the curing temperature on thermal polymerization, UV light intensity on photochemical polymerization, and exposure time during these processes on the electro-optical characteristics of PDLC films was thoroughly examined. Observations revealed that employing thermal polymerization during device preparation notably enhanced the permanent memory effect of the PDLC films. Sustained high transparency (TOFF = 45%) over an extended duration at room temperature, even subsequent to voltage cessation, was achieved. This transition initiated from an opaque state (T0 = 0%) through to a transparent state (TMAX = 65%), resulting in a substantial 70% permanent memory effect. [ABSTRACT FROM AUTHOR]

Photoalignment by azo dye nanolayers can provide high alignment quality for large-area liquid crystal devices. Application of this technology to active optical elements for signal processing and communications is a hot topic of photonics research. In this article, we review recent demonstrations and performance of liquid crystal photonic devices, discuss the advantages of the proposed technology, and identify challenges and future prospects in the research field of photoaligned multi-domain liquid crystal structures. We believe that the developments discussed here can provide directions for future research and potential opportunities for applications of liquid crystal devices based on multi-domain photoalignment. [ABSTRACT FROM AUTHOR]

Electro-optical effect-based liquid crystal devices have been extensively used in optical modulation techniques, in which the Kerr coefficient reflects the sensitivity of the liquid crystals and determines the strength of the device's operational electric field. The Peterlin–Stuart theory and the O'Konski model jointly indicate that a giant Kerr coefficient could be obtained in a material with both a large geometrical anisotropy and an intrinsic polarization, but such a material is not yet reported. Here we reveal a ferroelectric effect in a monolayer two-dimensional mineral vermiculite. A large geometrical anisotropy factor and a large inherent electric dipole together raise the record value of Kerr coefficient by an order of magnitude, till 3.0 × 10−4 m V−2. This finding enables an ultra-low operational electric field of 102–104 V m−1 and the fabrication of electro-optical devices with an inch-level electrode separation, which has not previously been practical. Because of its high ultraviolet stability (decay <1% under ultraviolet exposure for 1000 hours), large-scale production, and energy efficiency, prototypical displayable billboards have been fabricated for outdoor interactive scenes. This work provides new insights for both liquid crystal optics and two-dimensional ferroelectrics. [ABSTRACT FROM AUTHOR]

The polarization‐independent liquid crystal (LC) phase modulators can greatly improve the efficiency and reduce the complexity of the optical system. However, it is difficult for the LC phase modulator to achieve both good low‐loss modulation and polarization‐independent properties. A LC phase modulator of single layer microdomain twisted structure has been proposed to achieve good polarization independence and low loss in phase modulation. However, the multi‐exposure in fabrication is difficult to realize in production process. To simplify the fabrication process, an alternate LC (ALC) mask is proposed with the alternate arrangement of twist‐nematic (TN) LC and nematic LC. The fabrication process is optimized to two steps exposure with the usage of ALC and is suitable for large‐amount‐production. The measurement results showed that the single layer microdomain twisted LC phase modulator may get very low polarization dependence, about 3.52% under 2π phase modulation depth, with low loss. The device shows good potential application in optical communication, wearable device, and display. [ABSTRACT FROM AUTHOR]

Abstract This letter presents a Ka‐band low‐cost microstrip line phase shifter based on liquid crystal (LC) technology. Furthermore, a sum‐difference beamforming antenna array based on the LC phase shifter is designed. The phase shifter is composed of two coaxial connectors, a metal base, an intermediate dielectric layer, a gradient metal sheet and a top glass layer. The simulated results show that a nearly 360° phase shift coverage can be achieved with the effective permittivity of LC varying from 2.5 to 3.5. The sum‐difference beam antenna array is composed of a circulator, a sum‐difference network, a one‐to‐eight power‐division network, eight liquid crystal phase shifters, and a serious fed antenna array. The simulation results show that the antenna array can achieve sum‐difference beam scanning range of ±30°. A prototype of LC phase shifter is fabricated and tested. The results show that the designed LC phase shifter can achieve a 360° phase coverage by applying a direct current (DC) voltage ranging from 0 to 12 V. Compared to traditional phase shifters, the proposed design offers a simple structure at a lower cost. When applied in the design of a sum‐difference beam antenna array, it can reduce the producing cost and enable integrated design.

This letter presents a Ka‐band low‐cost microstrip line phase shifter based on liquid crystal (LC) technology. Furthermore, a sum‐difference beamforming antenna array based on the LC phase shifter is designed. The phase shifter is composed of two coaxial connectors, a metal base, an intermediate dielectric layer, a gradient metal sheet and a top glass layer. The simulated results show that a nearly 360° phase shift coverage can be achieved with the effective permittivity of LC varying from 2.5 to 3.5. The sum‐difference beam antenna array is composed of a circulator, a sum‐difference network, a one‐to‐eight power‐division network, eight liquid crystal phase shifters, and a serious fed antenna array. The simulation results show that the antenna array can achieve sum‐difference beam scanning range of ±30°. A prototype of LC phase shifter is fabricated and tested. The results show that the designed LC phase shifter can achieve a 360° phase coverage by applying a direct current (DC) voltage ranging from 0 to 12 V. Compared to traditional phase shifters, the proposed design offers a simple structure at a lower cost. When applied in the design of a sum‐difference beam antenna array, it can reduce the producing cost and enable integrated design. [ABSTRACT FROM AUTHOR]

The utilization of liquid crystal (LC) devices has become more significant in a wide range of technical applications due to their ability to modify optical characteristics and their versatility. Nevertheless, a crucial factor that impacts their performance is the stabilization of the photoalignment layer, which assumes a fundamental function in regulating the orientation of liquid crystals. The present study focuses on the difficulties and progress in achieving stability in the photoalignment layer utilized in liquid crystal devices. This paper provides an overview of the existing body of research, which encompasses a wide range of procedures, materials, and techniques that have been utilized to improve the stability of these layers. In this paper, we worked with different concentration ratios of RM257 on the SD1 alignment layer with different UV light polarization times. We studied that a higher concentration of RM and longer irradiation time gives a good photostability and the thickness of RM layers is also considerable like 5 nm the photoalignment properties of these materials are made possible by using photoalignment composite materials to create high‐quality liquid crystal photoalignment. The present analysis examines the constraints identified in prior studies, which encompass concerns related to longevity, environmental sensitivity, fabrication complexity, and performance trade‐offs. The abstract further emphasizes the crucial requirement for approaches that effectively manage the trade‐off between stability, optical quality, and feasible application in real‐life scenarios. Moreover, it underscores the need to comprehend degradation mechanisms for long‐term durability. The primary objective of this research study is to present a thorough and all‐encompassing examination of the area, with a specific focus on identifying potential future breakthroughs in stabilizing photoalignment layers for liquid crystal devices by UV polarization with a suitable RM concentration. [ABSTRACT FROM AUTHOR]

The relationship among the liquid crystal thickness, fringing field effect and diffractive efficiency of the Liquid Crystal on Silicon (LCoS) device is studied in this paper, by measuring two prepared LCoS devices working at 1550nm with liquid crystal thickness of 5µm and 7µm respectively. The width of the fly back region of the LCoS devices was measured under microscopy to characterize the effect of the fringing field effect. The results demonstrated that in most cases, the smaller the thickness of the liquid crystal layer, the narrower the fly back region, and the higher the diffractive efficiency, but the direction of the grating may also affect the width of the fly back region to a certain extent. [ABSTRACT FROM AUTHOR]

We consider new LC photonics devices based on photoalignment and photopatterning technology using azodye nanolayers. [ABSTRACT FROM AUTHOR]

Many researches have been carried out on the high performance of cholesteric liquid crystal (CLC), blue phase liquid crystal (BPLC) and sphere phase liquid crystal (SPLC), such as wide bandwidth, high reflectivity, multi‐wavelength, and good thermal stability. Among them, templating process is an attractive technique, which may induce the twist structure by polymer template and achiral nematic liquid crystals (LCs). A multi‐wavelength filter with Templated‐BPLCs was demonstrated that it may get much narrower bandwidth, better thermal stability compared with the CLC filters. Furthermore, the central wavelength and bandwidth can be easily controlled by the fabrication process and the optimization of the material concentration. And a high reflectivity CLC filter with a single‐layer template was proposed, which may reflect both right‐ and left‐handed polarized light. [ABSTRACT FROM AUTHOR]

We selected and summarized the most important aspects of liquid crystal alignment. Alignment by the surface profile and flat surface alignment are discussed as the main factors leading to the high-quality orientation of liquid crystals. The advanced level of understanding and formulation allows linking the alignment layer properties to the molecular structure of the alignment material. The paper reviews and combines the latest knowledge about liquid crystal alignment, dwells upon the relationship between the polar and azimuthal anchoring energy, explains the major particularities regarding anchoring measurements in the case of birefringent alignment materials with truly high azimuthal anchoring energy, and observes the current trends of water-friendly alignment materials and their application in geometrical phase device fabrication. [ABSTRACT FROM AUTHOR]

Intrinsically fluorescent liquid crystals are highly sought after for a variety of applications. Most of the measurements of photo-physical properties of liquid crystals are made in dilute solutions, which is mainly due to the relative ease of both these measurements and the interpretation of data. The fluorescence spectra depend on a number of parameters including the concentration in liquid crystal solutions, the device geometry, and the mesophase in which the spectra have been measured. Working with neat, or concentrated, liquid crystal samples adds experimental complexities such as the inner filter effect (IFE), which affects the collection of data, interpretation of the results, and accuracy of the conclusions. In this paper, we present a systematic study of the photo-physical properties of both a model reference material, Nile red, and a nematic liquid crystal, 4-cyano-4′-pentylbiphenyl (5CB). The influence on the emission spectra of an increasing solute concentration is investigated and discussed. Moreover, a detailed investigation of the influence of the used device geometry, as well as the choice of appropriate data fitting methodologies, are presented. [ABSTRACT FROM AUTHOR]

Thin-film-transistor-liquid crystal displays (TFT-LCDs) still dominate most of the display markets due to a big leap in image quality while keeping low cost and superior reliability, and its evolution is continuing to compete with emerging emissive displays. In this paper, recent progress in liquid crystal technologies mainly focusing on fringe-field switching (FFS) and polymer-stabilized vertical alignment (PS-VA) modes and materials for improving electro-optic performances is reviewed. [ABSTRACT FROM AUTHOR]

The electrical and non-linear optical characteristics of 1-dodecyl 3-methyl-imidazolium chloride (C12MIM.Cl or DDMIM.Cl) and 1-dodecyl 3-methyl-imidazolium bromide (C12MIM.Br or DDMIM.Br) ionic liquid crystals for optoelectronic devices were investigated in this study utilising B3LYP method and 6-311++G(d,p) basis set with Gaussian09 software. The majority of ionic liquid crystal research to date has been experiment-driven, with very few theoretical studies on the material's optical characteristics. Additional understanding of the behaviour of ionic liquid crystals is revealed through molecular spectroscopic research. The electronic properties (molecular energy band gap, electrostatic potential map and HOMO–LUMO orbitals) and spectroscopic (IR, UV) characteristics were assessed with the aid of a theoretical/computational model at B3LYP/6-311++G(d,p), whereas a nonlinear optical (NLO) study was carried out using the B3LYP and M06-2X methods with 6-31G(d) and 6-311++G(d,p) basis sets. Results demonstrate reasonable nonlinear optical characteristics in these molecules. [ABSTRACT FROM AUTHOR]

Polymer-stabilised liquid crystal devices have found widespread use in intelligent displays and dimming glass applications, but their high driving voltage induces high power consumption and needs to be reduced. In this paper, we use several small phenylacetylene molecule materials with linear structures to reduce the driving voltage and obtain a high contrast ratio in reverse-mode polymer-stabilised cholesteric liquid crystals (RPSCLC). In particular, the drive voltage of the 8-micron-thick sample was reduced by nearly 40%, and the 20-micron-thick sample was reduced by nearly 45%. Additionally, we explore the physical mechanism through which various small phenylacetylene molecule materials improve the electro-optical properties, based on polymer network morphology effects. The results will be of great value for enhancing the use of RPSCLC devices. [ABSTRACT FROM AUTHOR]

A simple and novel setup for high-frequency dielectric spectroscopy of materials has been developed using a portable vector network analyzer. The measurement principle is based on radio frequency reflectometry, and both its capabilities and limitations are discussed. The results obtained on a typical liquid crystal prove that the device can provide reliable spectra between 107 and 109 Hz, thus extending the capabilities of conventional impedance analyzers. [ABSTRACT FROM AUTHOR]

High-speed imaging of dynamic scenes is a challenging and important task in many applications. However, conventional imaging methods based on charge coupled devices or complementary metal oxide semiconductors have limitations in temporal resolution and photon sensitivity. To address this problem, we propose a novel high-speed imaging scheme that combines single-pixel imaging with single photon detection and time-correlated single photon counting. Our scheme can achieve high-speed imaging with 64 ps resolution by repeating the motion scenes and using binary outputs from single photon detectors. We demonstrate our scheme by reconstructing the switching process of a digital micro-mirror device and a liquid crystal spatial light modulator. Our scheme can be further improved to 1 ps resolution by using a more accurate time-correlated single photon counting system. Moreover, our scheme can adapt to different speed scenes by adjusting the temporal resolution and reducing the sampling time. Our high temporal resolution imaging scheme further expands the application areas of single-pixel imaging and provides solutions for scenes requiring single photon detection and higher temporal resolution, such as reproducible chemical reaction processes imaging, cellular or sub-cellular bio imaging, single-molecule imaging of rotary motors, high-speed equipment inspection, and other periodic high-speed scenes imaging. [ABSTRACT FROM AUTHOR]

In this paper, we propose new fast response FFS LC devices with virtual walls by using alternating (or multi) rubbing directions, which can be generated by using photo‐alignment. These new devices can offer much‐enhanced response‐speed compared to the conventional FFS LC device. By choosing different types of "local" LC molecular arrangements or designs (easily achievable by using photo‐alignment), we may be able to alter the virtual wall pitch length, and hence also alter the response speed and transmission of these fast response LC devices. These new designs can provide a new and alternative approach to generating virtual walls by "locally" varying the rubbing angle using photo‐alignment. These devices are attractive for VR applications where high speed operation of liquid crystal devices is required. [ABSTRACT FROM AUTHOR]

Spatial light modulators, as dynamic flat-panel optical devices, have witnessed rapid development over the past two decades, concomitant with the advancements in micro- and opto-electronic integration technology. In particular, liquid-crystal spatial light modulator (LC-SLM) technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude. These devices have gained significant interest in the nascent field of structured light in space and time, facilitated by their ease of use and real-time light manipulation, fueling both fundamental research and practical applications. Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications, covering topics as diverse as beam shaping and steering, holography, optical trapping and tweezers, measurement, wavefront coding, optical vortex, and quantum optics. Finally, we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.

The Journal of the Chinese Chemical Society (JCCS) recently published an editorial expressing gratitude to its supporters and announcing its achievements in 2023. The journal saw a modest increase in its impact factor, published 7 regular issues and 5 special issues, and received submissions from 38 countries. The editorial also announced the winners of the 2023 Best Article Award and introduced the Highly Cited Paper Award. JCCS plans to release a special issue in August 2024 focusing on precise measurement in analytical chemistry and curates virtual issues highlighting recent research. The journal aims to improve the quality of submissions and the review process while facilitating communication in the field of chemistry. [Extracted from the article]

Electrically driven multi-stable cholesteric liquid crystals can be used to adjust the transmittance of incident light. Compared with the traditional liquid crystal optical devices, the multi-stable devices only apply an electric field during switching and do not require a continuous electric field to maintain the various optical states of the device. Therefore, the multi-stable devices have low energy consumption and have become a research focus for researchers. However, the multi-stable devices still have shortcomings before practical application, such as contrast, switching time, and mechanical strength. In this article, the latest research progress on electrically driven multi-stable cholesteric liquid crystals is reviewed, including electrically driven multi-stable modes, performance optimization, and applications. Finally, the challenges and opportunities of electrically driven multi-stable cholesteric liquid crystals are discussed in anticipation of contributing to the development of multi-stable liquid crystal devices. [ABSTRACT FROM AUTHOR]

Tunable circular devices made of liquid crystals or other materials, like lenses, axicons, or phase plates, are often constrained by limitations in size, tunability, power, and other parameters. These constraints restrict their use and limit their applicability. In this review, a thorough study of the use of light's orbital angular momentum in the manufacturing of liquid crystal (LC) devices is presented. Twisted light fosters the simultaneous optimization of most critical parameters. Experimental demonstrations of the unmatched performance of tunable LC lenses, axicons, and other elements in parameters such as lens diameter (>1″), power and tunability (>±6 diopters), fill factor (>98%), and time response have been achieved by reversible vortex generation created by azimuthal phase delay. This phase delay can eventually be removed within the optical system so that lens performance is not affected. [ABSTRACT FROM AUTHOR]

In this work, we report on measurements of the contact angle of sessile droplets of aqueous solutions of a chromonic liquid crystal at different temperatures and concentrations and on different hydrophobic surfaces, and we show that the wettability of this complex fluid can be easily controlled by an external electric field. Specifically, electrically induced variations of the contact angle up to 70° were obtained using external DC voltages. Complementary tensiometric measurements of the aqueous solutions confirmed that the observed variations in the contact angle were mainly related to variations in the surface tension, while they did not show an evident connection with the internal molecular order of the liquid crystal droplets. Our study is relevant in view of the use of chromonic liquid crystals in microfluidic devices, where the control of wettability is an important tool for handling fluid flow. [ABSTRACT FROM AUTHOR]

Optical edge detection can significantly compress the data volume and is highly pursued in imaging processing. The commonly used methods extract the optical edge information but lose the capability to distinguish colors, which is another key information for imaging. Here, a design for color-selective optical edge detection is proposed and demonstrated with a cholesteric liquid crystal q-plate. The corresponding optical edge detection exhibits a narrow reflection band characteristic due to the one-dimensional photonic crystal configuration of the cholesteric liquid crystal. The monochromatic band is thermally and reversibly tuned ∼300 nm within 5.3 °C. Color-selective optical edge detection is verified by a series of chromatic images. This work introduces a thermally responsive liquid crystal device to release the color dimension of optical edge detection, which may upgrade existing imaging processing techniques. [ABSTRACT FROM AUTHOR]

The applications of liquid crystals continue to expand. They include conventional and advanced liquid crystal displays, electrically controlled lenses, tunable optical elements such as filters, light shutters, waveplates, and spatial light modulators, smart windows and sensors, and reconfigurable antennas and microwave devices, to name a few. As a rule, liquid crystal devices are controlled by applying an external electric field. This field reorients liquid crystals in a desirable way, thus leading to the tunability of their physical properties. The electric-field-induced reorientation of liquid crystals can be affected by ions typically present in molecular liquid crystals. In the case of liquid crystal displays, ions in liquid crystals can lead to image sticking, a reduced voltage holding ratio, and altered electro-optical performance. Therefore, the development of efficient ways to better control ions in liquid crystal devices is of utmost importance to existing and future liquid crystal technologies. In this paper, we discuss how nanomaterials can affect the electrical properties of molecular liquid crystals. In general, nanomaterials in molecular liquid crystals can behave as ion-capturing objects or act as a source of ions. Ion-capturing nanomaterials in molecular liquid crystals can enhance their electrical resistivity. On the other hand, ion-releasing nanoparticles can lead to the opposite effect. By considering the competition between two nanoparticle-induced ionic processes, namely the ion capturing and ion releasing effects, the electrical resistivity of liquid crystals can be controlled in a desirable way. [ABSTRACT FROM AUTHOR]

Polymer stabilised liquid crystal (PSLC) is widely used in various applications such as smart windows due to its fast response speed and wide viewing angle. However, there are still limitations in terms of high driving voltage and poor contrast ratio. Therefore, there is a need to explore methods to enhance the electro-optical performance of PSLC devices. In this paper, the influence of a few types of styryl molecules on the electro-optical characteristics of PSLC was investigated. The experimental results demonstrated that the addition of an appropriate amount of small styryl molecules significantly reduced the driving voltage and improved the contrast ratio. For an 8-micron-thick sample, the threshold voltage and saturation voltage were approximately 5.3 V and 6.5 V, respectively, resulting in a contrast ratio of approximately 14.4. For a 20-micron-thick sample, the threshold voltage, saturation voltage, and contrast ratio were approximately 10.2 V, 14.5 V, and 109, respectively. Combined with the effects of different small styryl molecules on the morphology of polymer networks, the physical mechanism of different small styryl molecules to improve electro-optical properties was studied. The findings will contribute to the advancement of RPSCLC devices and their practical applications. [ABSTRACT FROM AUTHOR]

We demonstrate using a diffractive smart window with homogeneous-aligned (HA) liquid crystals (LCs) owing to the large spatial phase difference in all directions in the opaque state. The proposed grating cell had a high haze value (88.57%), which was 1.16 times higher than the previously reported vertically aligned (VA) grating cells because the proposed grating cell had a higher twist angle than what the VA grating cell had. Our proposed HA grating cell can be used in various smart window applications. [ABSTRACT FROM AUTHOR]

In recent years, the emergence of virtual reality (VR) and augmented reality (AR) has revolutionized the way we interact with the world, leading to significant advancements in 3D display technology. However, some of the currently employed 3D display techniques rely on stereoscopic 3D display method, which may lead to visual discomfort due to the vergence-accommodation conflict. To address this issue, several true 3D technologies have been proposed as alternatives, including multi-plane displays, holographic displays, super multi-view displays, and integrated imaging displays. In this review, we focus on planar liquid crystal (LC) devices for different types of true 3D display applications. Given the excellent optical performance of the LC devices, we believe that LC devices hold great potential for true 3D displays. [ABSTRACT FROM AUTHOR]

A polymer-stabilized liquid crystal (PSLC) device has been a promising candidate in several scenarios like smart vehicle windows and glass curtain walls in recent years due to its remarkable features like a fast switch from the initial transparent state to the scattering state with a rather low driving voltage, high transmittance at off-state, and broad viewing angle. The electro-optical characteristics of PSLC devices are determined by the synergistic attributions of liquid crystal (LC) molecules and the influence of the polymer network exerted on the movement of LC molecules. A systematic study of the influence of the polymer network on the movement of LC molecules is conducted, with the polymer network formed by methoxy/cyano/carboxyl monomers and diacrylate C6M. The polymer network morphology of PSLC film is greatly affected by the molecular structures and content of monoacrylic monomers. Additionally, the electro-optical performance and peel strength of PSLC films could be improved by modulating the molecular structures and morphology of polymer networks. PSLC devices containing carboxyl monomers show enhanced electro-optical performance and peel strength due to their directional filiform topology. This study might provide guidance for optimizing the performance of PSLC devices and establishing the relationship between the molecular structure, polymer network morphology, and electro-optical performance of reverse-mode dimming films. [ABSTRACT FROM AUTHOR]

Microfluidic platforms enable more precise control of biological stimuli and environment dimensionality than conventional macroscale cell-based assays; however, long fabrication times and high-cost specialized equipment limit the widespread adoption of microfluidic technologies. Recent improvements in vat photopolymerization three-dimensional (3D) printing technologies such as liquid crystal display (LCD) printing offer rapid prototyping and a cost-effective solution to microfluidic fabrication. Limited information is available about how 3D printing parameters and resin cytocompatibility impact the performance of 3D-printed molds for the fabrication of polydimethylsiloxane (PDMS)-based microfluidic platforms for cellular studies. Using a low-cost, commercially available LCD-based 3D printer, we assessed the cytocompatibility of several resins, optimized fabrication parameters, and characterized the minimum feature size. We evaluated the response to both cytotoxic chemotherapy and targeted kinase therapies in microfluidic devices fabricated using our 3D-printed molds and demonstrated the establishment of flow-based concentration gradients. Furthermore, we monitored real-time cancer cell and fibroblast migration in a 3D matrix environment that was dependent on environmental signals. These results demonstrate how vat photopolymerization LCD-based fabrication can accelerate the prototyping of microfluidic platforms with increased accessibility and resolution for PDMS-based cell culture assays. [ABSTRACT FROM AUTHOR]