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Owing to the passive nature of liquid crystal (LC) materials, achieving luminous displays using pure LC materials is challenging. In addition, it is difficult to achieve a fast switching time using pristine ferroelectric LC devices without compromising their cell thickness. Herein, we have developed a fast switching and highly luminescent electro-optical device by dispersing a minute concentration of bimetallic nanoparticles (Au@Ag NPs) having a spherical gold core and a silver shell within a ferroelectric liquid crystal (FLC) host matrix, ZLI3654. Au@Ag core–shell NPs having synergic attributes of both counterparts were successfully synthesized by a facile seed-mediated route. The Au core helps to tune the shape of the Ag shell and provides enhanced electron density as well as improved stability against oxidation. Introducing nanoparticles induces little structural modifications to the host FLC, resulting in an improvement in the mesogenic alignment. Interestingly, ∼29-fold enhancement in the photoluminescence (PL) intensity is observed on dispersing 0.25 wt% of Au@Ag NPs into the FLC host matrix. The enhanced electromagnetic field in the FLC-nanocomposite is attributed to the Localized Surface Plasmon Resonance of Au@Ag NPs, which strengthens the photon absorption rates by the FLC molecules, culminating in the massive enrichment of the PL intensity. In addition, the improved localized electric field inside the FLC device led to a noticeable enhancement in the spontaneous polarization, dielectric permittivity, and, most interestingly, ∼53% fastening in the switching time at an optimum concentration (0.25 wt%) of Au@Ag NPs. The improved electro-optical parameters of the Au@Ag NPs/FLC composite have been compared with the performance of both pristine Au NPs/FLC and Ag NPs/FLC composites, respectively, for the comprehensiveness of the study. The present study paves a systematic way to develop FLC-based advanced electro-optical devices with faster switching and higher luminescence properties. [ABSTRACT FROM AUTHOR]

Interest in fullerene-based polymer structures has renewed due to the development of synthesis technologies using thin C60 polymers. Fullerene networks are good semiconductors. In this paper, heterostructure complexes composed of C60 polymer networks on atomically thin dielectric substrates are modeled. Small tensile and compressive deformations make it possible to ensure appropriate placement of monolayer boron nitride with fullerene networks. The choice of a piezoelectric boron nitride substrate was dictated by interest in their applicability in mechanoelectric, photoelectronic, and electro-optical devices with the ability to control their properties. The results we obtained show that C60 polymer/h-BN heterostructures are stable compounds. The van der Waals interaction that arises between them affects their electronic and optical properties. [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]

In this study, a novel light switch was developed by integrating polymer dispersion liquid crystals (PDLC) and polymer-stabilised cholesteric liquid crystals (PSCLC), leveraging the infrared shielding properties of these two liquid crystal films. The optimal formulation for each layer of the liquid crystal structure was investigated. Subsequently, the effects of light intensity, high temperature, and humidity on the performance of the light switch were examined. This new light switch can be selectively driven layer by layer at room temperature, achieving three states: the off state, PDLC layer-driven state, and full-driven (on state). This functionality serves the purpose of electrogenerated temperature control. Samples under optimal conditions exhibited a 31% enhancement in infrared shielding compared to a single-layer PDLC film. Moreover, the IR shielding rate could be adjusted according to the voltage applied, realising an intelligent temperature-control effect. The results of this study suggest that such bilayer liquid crystal structures hold significant potential for application in electro-optical devices and smart curtain systems. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescent (TADF) emitters attract interest as organic light‐emitting diode (OLED) materials with potentially 100% internal quantum efficiency (IQE). Their application in commercial displays is still hindered due to the not yet sufficient operational stability. We analyze the degradation mechanism in a TADF OLED by combining electro‐optical characterization and device simulations. We find that two trap states are being created at the HTL/EML interface during initial degradation. [ABSTRACT FROM AUTHOR]

The paper comprehensively addresses the integration of advanced technologies to enhance defense capabilities, with a particular focus on critical tasks such as object detection, tracking, and distance measurement. To this end, the integration of IMX219-77 cameras and Nvidia Jetson Nano is proposed, emphasizing the utilization of their respective features. Commonly used tools like open source computer vision (OpenCV) and GStreamer are preferred for ensuring cohesive integration between hardware and software components. On the software front, tools such as OpenCV and GStreamer are preferred for tasks related to computer vision and multimedia processing. The MOSSE algorithm is selected for object tracking due to its speed, efficiency, and resilience to changes in lighting conditions. Additionally, distance measurement is achieved through the use of Stereo Vision techniques. The results of the study demonstrate the effectiveness and accuracy of the proposed integration. It is found that accurate distance measurements with a margin of error ranging from 0 to 2 mm, falling within acceptable limits mentioned in relevant literature, can be achieved. This underscores the efficacy of the proposed technologies for tasks such as object detection, tracking, and distance measurement. The aim of the study is to conduct an in-depth examination of the integration of advanced tools such as IMX219-77 cameras and Nvidia Jetson Nano for use in defense operations. It seeks to showcase how this integration can strengthen defense strategies and provide protection against potential threats. Additionally, the study aims to lay the groundwork for ongoing innovation and development in defense technologies. In conclusion, the integration of electrooptical systems and computer vision technologies has the potential to significantly enhance defense capabilities and contribute to national security efforts. The advantages provided by this integration can serve as a valuable resource for researchers seeking to develop new solutions in defense and security domains. [ABSTRACT FROM AUTHOR]

We have developed a double-layer liquid crystal light shutter and investigated its temperature dependent morphological, electro-optical, and dielectric properties. The optical layers of the shutter are in direct contact, reducing optical losses. The shutter comprises a polymer dispersed liquid crystal film adjacent to an azo dye methyl red and CdSeS/ZnS quantum dot doped cholesteric liquid crystal layer. This novel double-layer light shutter device is switchable between opaque and transparent states at room temperature, and it exhibits low threshold and saturation voltages. Both the threshold (V th) and saturation (V sat) voltages are found to decrease with increasing temperature. The electrical characteristics of the shutter, namely the real part of dielectric constant (ε′) and the ac conductivity (σ ac) also increase with temperature in the low frequency region. Our results show that this double-layer light shutter has interesting potential for simple electro-optical devices and smart window applications. • A double-layer light shutter consisting of polymer dispersed liquid crystal and azo dye/quantum dot doped cholesteric liquid crystal composite was produced. • Temperature dependent electro-optical and dielectric properties of double-layer light shutter were investigated. • Threshold voltage (V th), saturation voltage (V sat), and contrast ratio (CR) parameters of double-layer light shutter were decreased with increasing temperature. • Dielectric constants (ε ′ and ε ′′) and ac conductivity (σ ac) values of double-layer light shutter were increased with increasing temperature. [ABSTRACT FROM AUTHOR]

CuInS2/ZnS core/shell quantum dots (CIS/ZnS QDs) dispersed ferroelectric liquid crystal (FLC) mixtures have been characterized for their application in electro-optical devices, energy storage, and solar cells. Physical properties of the CIS/ZnS QD-FLC (ferroelectric liquid crystal) mixtures have also been investigated with varying QD concentrations in order to optimize the critical concentration of QDs in mixtures. The presence of QDs breaks the geometrical symmetry in the FLC matrix, which results in a change in the physical properties of the mixtures. We observed the reduced values of primary and secondary order parameters (tilt angle and spontaneous polarization, respectively) for mixtures, which also depend on the concentration of QDs. The reduction of spontaneous polarization in QDs-FLC mixtures is attributed to the adverse role of flexoelectric contribution in the mixtures. The 92% faster electro-optic response and enhanced capacitance indicate the possible application of these mixtures in electro-optical devices and solar cells. Photoluminescence emission of pure FLC and QDs-FLC mixtures has been thermally tailored, which is explained by suitable models. [ABSTRACT FROM AUTHOR]

Colloidal liquid crystals are an emerging class of soft materials that naturally combine the unique properties of both liquid crystal molecules and colloidal particles. Chiral liquid crystal blue phases are attractive for use in fast optical displays and electrooptical devices, but the construction of blue phases is limited to a few chiral building blocks and the formation of blue phases from achiral ones is often counterintuitive. Herein we demonstrate that achiral dumbbell-shaped colloids can assemble into a rich variety of characteristic liquid crystal phases, including nematic phases with lock structures, smectic phase, and particularly experimental observation of blue phase III with double-twisted chiral columns. Phase diagrams from experiments and simulations show that the existence and stable regions of different liquid crystal phases are strongly dependent on the geometrical parameters of dumbbell-shaped colloids. This work paves a new route to the design and construction of blue phases for photonic applications. Colloidal liquid crystals account for various applications due to the combination of characteristics relevant for liquid crystals and colloids. The authors elaborate the impact of concave geometry on the properties of colloidal liquid crystals for development of functional materials. [ABSTRACT FROM AUTHOR]

This document, titled "P-13.4: Electro-optical properties of frequency-switched graphene oxide liquid crystal," discusses the electro-optical properties of graphene oxide (GO) liquid crystal (LC) material. The study explores the influence of electric frequency on the electro-optical behaviors of GO-LC and the potential for tuning its properties using the frequency-switched method. The research finds that the birefringence of GO-LC initially increases with frequency, reaches a saturated state, and then declines as the frequency exceeds 500 kHz. The optimal frequency range for maximum birefringence value varies with concentration. The study concludes that the interference intensity and sensitivity of GO-LC can be controlled by tuning the electric frequency within the optimal range. [Extracted from the article]

Effects of luminescent coupling are observed in monolithic 5V, five-junction GaAs phototransducers. Power conversion efficiency was measured at 61.6%±3% under the continuous, monochromatic illumination for which they were designed. Modeling shows that photon recycling can account for up to 350mV of photovoltage in these devices. Drift-diffusion based simulations including a luminescent coupling term in the continuity equation show a broadening of the internal quantum efficiency curve which agrees well with experimental measurements. Luminescent coupling is shown to expand the spectral bandwidth of the phototransducer by a factor of at least 3.5 for devices with three or more junctions, even in cases where multiple absorption/emission events are required to transfer excess carriers into the limiting junction. We present a detailed description of the novel luminescent coupling modeling technique used to predict these performance enhancements. [ABSTRACT FROM AUTHOR]

Detailed investigations of the quadratic nonlinear response of a series of new polyimides with covalently attached chromophore DR13 are performed by the Maker fringes method in the range of fundamental wavelength from 850 to 1450 nm. Polymer films with thickness of 100–400 nm were spin-coated on glass substrates and corona poled. For these materials, the maximum values of the second harmonic generation coefficients d33 are 80-120 pm/V. A red shift of the nonlinear response dispersion with respect to the linear absorption spectrum was observed for the DR13 chromophore. The temperature dependences of linear absorption and nonlinear coefficients d33 for studied structures are observed. It was found that the temperature changes of the absorption spectra lead to appreciable contribution to the value of the nonlinear coefficient d33. The demonstrated high temperature stability (up to 120 °C) of chromophore-containing polyimide thin films makes it possible to eliminate the degradation of their nonlinear optical properties in the future applications of such structures. [ABSTRACT FROM AUTHOR]

The societal impact of liquid crystals (LCs) in electrooptical displays arrived after decades of research involving molecular-level design of LCs and their alignment layers, and elucidation of LC electrooptical phenomena at device scales. The anisotropic optical, mechanical and dielectric properties of LCs used in displays also make LCs remarkable amplifiers of their interactions with chemical and biological species, thus opening up the possibility that LCs may play an influential role in a data-driven society that depends on information coming from sensors. In this article, we describe ongoing efforts to design LC systems tailored for chemical and biological sensing, efforts that mirror the challenges and opportunities in LC design and alignment tackled several decades ago during development of LC electrooptical displays. Now, however, traditional design approaches based on structure–property relationships are being supplemented by data-driven methods such as machine learning. Recent studies also show that computational chemistry can greatly increase the rate of discovery of chemically responsive LC systems. Additionally, non-equilibrium states of LCs are being revealed to be useful for design of biological sensors and more complex autonomous systems that integrate self-regulated actuation along with sensing. These topics and others are addressed in this article with the aim of highlighting approaches and goals for future research that will realise the full potential of LC-based sensors. [ABSTRACT FROM AUTHOR]

Integrated optical computing has the potential to enhance the computation abilities in terms of computing speed and power consumption during the post-Moore's law era. As one of the widely investigated approaches, electro-optic logic uses electro-optic switches as the building blocks to achieve complex functions. In this paper, we propose and experimentally demonstrate a multioperand electro-optic logic gate that contains multiple active regions in a single gate to further increase the versatility of gates. Thus, one gate can be controlled by several electrical inputs simultaneously. The ability of multioperand logic gates is thoroughly explored. The detailed comparison shows that the proposed gate can largely improve the circuit performance in terms of the area, latency, power, and insertion loss. We believe the multioperand logic gate has the potential to contribute to a more compact and power-efficient integrated optical computing system. [ABSTRACT FROM AUTHOR]

The embedded luminance sensor utilizes the electro‐optical properties of a‐Si film can indeed work for adjusting the degree of illuminance on a LCD panel. By screening the appropriate gate current, we can get the suitable leakage current and make the embedded luminance sensor have better electro‐optical characteristics. The results of reliability experiment also show us that the photo sensor has good performance under suitable electrical condition. [ABSTRACT FROM AUTHOR]

An attempt for specifying the concept of input effects has been made in the article in order more data to be systematized about them, to be specified the composition and their effect over the planning and functioning of electro-optical device. An analysis has been made, showing the impact of the input effects over the functionality of the electronic-optical device for measuring the position of distant objects according to angular coordinates. [ABSTRACT FROM AUTHOR]

The development of new organic simple and low-cost fluorophores is a current topic. To date innovative solutions include azo dyes because of the unique absorption behavior, but the azo group gives poor luminophores in the solid state. In order to produce a luminescent azo dye, we synthesized compound A2 , 4,4′-((1,1′)-(2,5-dimethoxy-1,4-phenylene)bis(diazene-2,1-diyl))dianiline, and its symmetrical Schiff-base derivative C2. The new compound C2 is a weakly luminescent fluorophore in the crystalline phase and when employed as building blocks in self-assembly of zinc (II) coordination polymer. Nevertheless, if used as a dopant in PS and PVK, C2 shows enhanced fluorescence and represents a good on-off naked-eye switch when dispersed in a room-temperature nematic polymer. PL azo dyes are very rare. We produced the symmetrical azo fluorophore C2 with considerable PL performances. The new fluorophore C2 is a yellow emitter weakly fluorescent in the crystalline phase but remarkably luminescent as a dopant in PS, PVK and in a LC matrix for on-off naked-eye PL switch. Unlabelled Image • A fluorescent azo dye employable for optical and electrooptical devices was synthetized. • Azobenzene fluorophores are investigated as emitters for LEDs and OLEDs. • The dye was employed as dopant in polymer matrixes and in the preparation of a zinc coordination polymer. [ABSTRACT FROM AUTHOR]

From a diamino dicyano-phenylenevinylene skeleton a symmetrically di-salen dye was obtained and employed both as a dopant in non-emissive polymer matrixes and as building blocks in the preparation of a zinc self-assembly polymer. The new fluorophore C1 belongs to the class of the luminescent liquid crystals (LLCs). The molecule produces red emission in the crystalline phase and yellow luminescence in the nematic phase, which dramatically decreases in on-off switch mode after LC order was lost. Both C1 and its self-assembly zinc-based coordination polymer suffers a lot aggregation caused quench effect (ACQ). Conversely, thin films obtained by dispersion in polystyrene (PS) and poly(9-vinylcarbazole) (PVK) show remarkably enhanced fluorescence, reaching the noteworthy value of 77% Photoluminescence Quantum Yield (PLQY) for the PVK doped sample. Unlabelled Image • A fluorescent organic dye employable for optical and electrooptical devices was synthetized. • Cyano-phenylenevinylene (PV) derivatives are widely investigated fluorogens for emitting layers. • The dye was employed as dopant in polymer matrixes and in the preparation of a zinc coordination polymer. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To deal with the registration of infrared and visible image with significant difference in contrast and large geometric distortion in electro-optical pod, a robust and fast registration method by using common structural features is proposed in this paper. First, to adjust the scales of input images, a geometric transformation model is built based on parameters of the cameras. Then, a global structural feature extraction strategy is developed by using phase congruency and significance ranking space. Those features are not only invariant to the scale and contrast but also embody the structural of the input images maximally and uniformly. Finally, to enhance the robustness to contrast, blurring, and incompleteness of structures, an adaptive feature matching method with kernelized correlation filter is presented. Experimental results demonstrate that the proposed method has better performance than several state-of-the-art methods in robustness and precision, and also confirm its validity in the real environment. [ABSTRACT FROM AUTHOR]

Measuring the transient voltages, including lightning or switching impulse overvoltage, is helpful for accident analysis of power system and insulation design. In this paper, a contactless transient voltage measuring system based on a metal-free integrated electro-optic electric field sensor was proposed, implemented, and tested. The lightning and switching impulse transients are proportional to the electric field they generate, and vice versa, enabling measurement of the transient voltage by measuring the associated electric field. The proposed method uses an electric field sensor to directly measure the field generated by the voltage without any capacitive coupling. In addition, a method to decouple the multiphase coupling was proposed. The performances of the measuring system were tested by simulation experiments and compared with that of a standard divider. The field data of the transient overvoltage on a 220 kV bus during the process of putting a capacitor voltage transformer into operation were given. The measurement results were found to coincide with the related physical process. [ABSTRACT FROM AUTHOR]

Microscale gas breakdown plays a critical role in microplasma generation for numerous applications and device lifetime for miniaturized electronics. This communication extends a previous investigation of pulsed breakdown morphology [G. Meng et al., Phys. Plasmas 25, 082116 (2018)] by providing further insight into the spatio-temporal dynamics of pulsed gas breakdown for different gap distances using an in-situ electrical-optical measurement method. Time-resolved sequential images and the corresponding photon number distributions are obtained to demonstrate the dynamic evolution of the breakdown channel morphology and the ionization intensity during breakdown development. For a 15 μm gap, breakdown transitions from a spot area on both electrode surfaces to a broad discharge region comprised of filamentary main breakdown channel (∼2.00 μm) and surrounding weak ionization area due to the local field enhancement. For a 2 μm gap, it transitions from a thin channel (∼1.09 μm) to a wider and uniform channel (∼2.14 μm) because the electric field is more uniform at smaller gaps. Interestingly, the main breakdown channel width at the instant of breakdown is independent of the gap width. For the 2 μm gap, field emission dominates the initial stage of breakdown and collision ionization (α process) dominates during breakdown development, while the Townsend avalanche dominates the breakdown process for the 15 μm gap. We apply a simple asymptotic theory to quantify the relative contribution of these phenomena and predict that breakdown will follow Paschen's law for gaps larger than 17.8 μm. [ABSTRACT FROM AUTHOR]

Abstract As well known, micro and nanosatellites are being proposed for a variety of space missions, due to the advantages offered in terms of flexibility, cost and development time-scales. They also allow the development of space missions based on distributed architectures, composed of a number of small platforms in coordinated flight. However, technological advancements are still needed to make micro and nanosatellite competitive with respect to larger platforms. In this paper, we explore the potentiality offered by hyper hemispheric lens for the development of miniaturized and multi-function sensors for use on board of micro satellites. Hyper hemispheric lens belong to the ultra-wide field-of-view optical objectives. Here a novel optics of this category is presented. Its field of view is 360° in azimuth (panoramic capabilities) and 135° for the off-boresight angle (hyper-hemispheric field). With such capabilities the lens may be exploited as a very-large field-of-view optics where moving parts can be avoided. This is of interest to space applications, in which devices with any moving part, representing a possible point of failure, shall be avoided or reduced to the minimum. A hyper hemispheric lens may, then, be adopted for electro optical devices in space satellite subsystems, such as star-, Sun- and Earth-sensors, or for monitoring the environment surrounding the satellite in the case of on-orbit servicing or active debris removal operations. Weight and cost budgets for small and micro satellites are also important parameters to determine their success. Hyper hemispheric lens may be kept quite compact in dimension and the need of a single imaging detector, for a so large field of view, strongly reduces costs. In this paper, we explore possible applications of a multi-purpose space device based on a hyper hemispheric lens on board of micro and nanosatellites. [ABSTRACT FROM AUTHOR]

Highlights • Compensate tracking boresight error by providing jitter for the signal light. • The electro-optic modulator (EOM) is used to provide jitter. • The EOM is used to estimate the boresight error. • The digital optical phase-locked loop is used. • The mixing efficiency and sensitivity of the communication system is well improved. Abstract A method for compensating the tracking boresight error by providing additional jitter for the signal light is proposed. The relationship between jitter angle and system performance is analyzed, which shows the sensitivity attenuation is within 0.1 dB when the angle is within 0.2–1.2 μrad. The optimal mathematical model of output power and compensation angle estimation is established. And the simulation results show the mixing efficiency of the coherent optical communication system is well improved. [ABSTRACT FROM AUTHOR]

Abstract The paper presents electrooptic properties of PDLC films obtained by photopolymerization-induced phase separation in different conditions and deposited on elastic substrates having different resistivity. The effect of the curing rate on the morphology of PDLC composite was confirmed. The faster is curing the lower is diameter of liquid crystal droplets and consequently switching voltages are higher and switching times are shorter. Choosing the proper liquid crystalline mixture for given polymer matrix one should take into account optical and dielectric properties, moreover solubility of mixture components in cured polymer matrix as well as their surface tension with respect to partly cured prepolymer. Both latter features can affect liquid crystal droplet shape and effective clearing point. It was shown that the resistivity of conducting layer of the elastic substrates can affect the morphology of the PDLC composite and consequently its electrooptic characteristics. Highlights • The effect of components properties on the PDLC morphology. • The effect of the resistance of conducting layer on the morphology and electrooptic properties of PDLC. • The reduction of the PDLC driving voltage. [ABSTRACT FROM AUTHOR]

Abstract We developed an alignment method for control of the polar pretilt angle at the boundaries of a liquid crystal (LC) layer in a continuous range 2–90° by introducing a low-density polymer network. The network was formed as a result of the electric field-induced segregation of a photo-reactive monomer added in concentrations of 0.5–1% to the LC host and subsequent in-situ UV-light-induced polymerization. LC director was "frozen" within a less than a micron-thick layer in the vicinity of the cell substrates at high average tilt angles anchoring the LC in the bulk similarly to a high-pretilt alignment layer. The resultant pretilt angle was determined by the voltage applied before and during polymerization and the duration of voltage application before UV-light exposure. The desired pretilt angle could be set over a small area of a sample which allowed for the fabrication of LC devices with spatially variable optical retardation. Using this method, we fabricated high-pretilt splay and bend LC cells, optically recorded converging lenses and bi-prisms with electrically controlled optical characteristics, and phase diffraction gratings with resolution better than 50 lines/mm. Highlights • We developed an effective method of pretilt angle control in nematic liquid crystal cells. • The paper includes our newest results on stabilization of high-pretilt bend structures in π-cells, the fastest display modes. • Our method of pretilt control eliminates a need for a photo-lithographically manufactured electrodes. • We present examples of an optically recorded lens, prism, and phase diffraction grating. • The optical elements demonstrate low light scattering, which allows for the commercial application. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we present a graphene-based plasmonic electro-optical multi-logic gate (MLG) operating at THz frequency. The designed MLG supports AND, XNOR, and NOR logic gates in a graphene-dielectric-metal structure, simultaneously. The propagation length of the surface plasmons (SPs), stimulated by a 27.35 THz incident TM wave, is about 62 times larger in ON state compared to OFF state. Simulation results by the finite difference time domain (FDTD) method show the minimum extinction ratio (ER) of 29.41, 97.38, and 29.40 dB for AND, XNOR, and NOR logic gates, respectively. Also, the minimum modulation depth (MD) is obtained 99.99% for XNOR and 99.88% for AND and NOR logic gates. The proposed MLG provides a high extinction ratio and ultra-compact logical block for using in digital processing circuits and THz applications. Highlights • Using graphene-dielectric-metal structure to stimulate the surface plasmons. • Supporting AND, XNOR, and NOR logic gates in a simple structure, simultaneously. • Having an ultra-compact footprint compared to the working wavelength. • Obtaining high extinction ratios and modulation depths for all three logic gates. [ABSTRACT FROM AUTHOR]

Thin films of WO 3 :H (~450 nm) were prepared on indium tin oxide (ITO) coated glass by reactive direct current magnetron sputtering at room temperature. The visible transmittance of the original state, and the X-ray photoelectron spectroscopy analysis of WO 3 :H films prove that H + ions have been introduced into the structure of WO 3 . Based on the optimized parameters of WO 3 :H thin film, the Glass/ITO/WO 3 :H/Ta 2 O 5 /NiO x /ITO electrochromic devices (ECDs) are prepared monolithically by magnetron sputtering. Different applied voltages of 1.0, 2.0 and 3.0 V were applied to the ECD for investigating its influence on the ECD's optical contrast and cycle life. Though the ECD can get a higher contrast about 42% at 550 nm under 3.0 V voltage, however, it will be destructed quickly. When the operating voltage is 2.0 V, the ECD has a stable cycle performance with the optical contrast of >30%. [ABSTRACT FROM AUTHOR]

We report a $1\times 2$ optofluidic switch which consists of a fluidic chamber and an electrowetting chamber. The fluidic chamber can realize light routing and power distribution. The electrowetting chamber can switch the light on and off. On the whole, the device can achieve a distribution of the incident light power to two outputs in any proportion (from 0% to 100%), and the light in each output can be switched on and off completely. Besides, due to light routing, the light loss of the proposed optofluidic switch is relatively low. The measured light loss of the device is less than ~0.35 dB. The proposed optofluidic switch has potential applications in optical switching networks, beam splitters, variable optical attenuators, and optical routers. [ABSTRACT FROM AUTHOR]

The doping of Cu2ZnSnSe4 semiconductor with Ge element has demonstrated improvements to kesterite solar cell efficiency. However, the impact of different Cu concentrations on Cu2ZnSnGeSe4/CdS solar cell performance has been poorly studied. In this work, Cu2ZnSnGeSe4 thin films with different Cu contents were synthesized by selenization of sequential thermal evaporation precursors. Solar cells based on kesterite-type Cu2ZnSnGeSe4 (CZTGSe) were fabricated and the influence of the Cu thickness on the chemical composition and morphology of the layers and electro-optical properties of solar cells was studied. The stacking process was performed at room substrate temperature. Efficiency values in the range of 2.0-6.8% are reported as a function of Cu concentration. The highest efficiency of 6.8%, was achieved for solar cell with glass/Mo/CZTGSe/CdS/i-ZnO/ITO structure using the stacking of Cu (3 nm)/Sn (248 nm)/Cu (112 nm)/Zn (174 nm)/Ge (20 nm). [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) thin film has in recent years emerged due to its unique physical, electrical and chemical properties. The microstructural and optical properties of nanocrystallite ZnO films fabricated using electrospinning and post-calcination, undoped and doped with aluminum, (AZO nanostructure films) were investigated in this study. The results indicated that the crystallized and monolithic AZO films comprised perfectly linked ZnO nanoparticles (NPs). Al incorporation deformed the lattice geometry ( a and c axis) and crystallite size of (002) plane, and led to formation of zinc vacancies and Al interstitial/substituted sites. Functional molecule groups and optical properties of pristine ZnO and AZO films were studied by far-FTIR, PL and UV–Vis techniques. Our findings showed that doping ZnO with Al resulted in the Zn-O bond shifting towards higher energy levels, and it polarized the visible lights more than pure ZnO thin films. Furthermore, the formation of the large concentration of point defects in sub-atomic structure of AZO (6 wt% Al) reduced the optical band gap energy of ZnO from the 3.4 e.V to 3.05 eV. The optical transmittance of AZO films was higher than 83% in visible light range. The electrical conductivity of ZnO film was improved by Al incorporation. The results of present work indicated that the electrospinning is a promising method to fabricate the nanostructured AZO films for use in electro-optical applications such as solar cells. [ABSTRACT FROM AUTHOR]

In this paper, the bimodal amplitude-and frequency modulation method of atomic force microscopy (AFM) is applied to investigate the residual oil film on KDP crystal surface after polishing and surface cleaning. The thickness map of residual oil film is obtained based on the relationship between the cantilever resonant frequency shift and the surface stiffness. The thickness maps measured by AFM and spectroscopic imaging ellipsometry methods are compared, and the results obtained by two methods are consistent. The measurement scheme extends the application of AFM technology to characterize the residual oil on the KDP surface quality quantitatively after polishing and surface cleaning. [ABSTRACT FROM AUTHOR]

Electro-optical measurements, i.e., optical waveguides and plasmonic based electrochemical impedance spectroscopy (P-EIS), are based on the sensitive dependence of refractive index of electro-optical sensors on surface charge density, modulated by an AC electrical field applied to the sensor surface. Recently, P-EIS has emerged as a new analytical tool that can resolve local impedance with high, optical spatial resolution, without using microelectrodes. This study describes a high speed image acquisition and processing system for electro-optical measurements, based on a high speed complementary metal-oxide semiconductor (CMOS) sensor and a field-programmable gate array (FPGA) board. The FPGA is used to configure CMOS parameters, as well as to receive and locally process the acquired images by performing Fourier analysis for each pixel, deriving the real and imaginary parts of the Fourier coefficients for the AC field frequencies. An AC field generator, for single or multi-sine signals, is synchronized with the high speed acquisition system for phase measurements. The system was successfully used for real-time angle-resolved electro-plasmonic measurements from 30 Hz up to 10 kHz, providing results consistent to ones obtained by a conventional electrical impedance approach. The system was able to detect amplitude variations with a relative variation of ±1%, even for rather low sampling rates per period (i.e., 8 samples per period). The PC (personal computer) acquisition and control software allows synchronized acquisition for multiple FPGA boards, making it also suitable for simultaneous angle-resolved P-EIS imaging. [ABSTRACT FROM AUTHOR]

A new octave bandwidth high selectivity compact microstrip diplexer working in the band from 10 to 20 GHz is presented, intended to be a part of an electro-optical interferometer covering the whole frequency band. The circuit is based on the combination of hybrid couplers and bandpass filters both on the microstrip technology. The diplexer provides two output frequency bands which cover the 10–14 GHz (relative bandwidth of 33%) and the 16–20 GHz (relative bandwidth of 22%) ranges, respectively, with a stop band in between from 14 to 16 GHz. Measured results show a insertion loss level of 3.3 dB for both output bands and high selectivity performance, exhibiting a rejection level between output bands higher than 20 dB and return loss better than 10 dB in all ports. [ABSTRACT FROM AUTHOR]

Purpose: To study the accommodative dynamics for predictable and unpredictable stimuli using manual and automated accommodative facility tests Materials and Methods: Seventeen young healthy subjects were tested monocularly in two consecutive sessions, using five different conditions. Two conditions replicated the conventional monocular accommodative facility tests for far and near distances, performed with manually held flippers. The other three conditions were automated and conducted using an electro-optical system and open-field autorefractor. Two of the three automated conditions replicated the predictable manual accommodative facility tests. The last automated condition was a hybrid approach using a novel method whereby far and near-accommodative-facility tests were randomly integrated into a single test of four unpredictable accommodative demands. Results: The within-subject standard deviations for far- and near-distance-accommodative reversals were (±1,±1) cycles per minute (cpm) for the manual flipper accommodative facility conditions and (±3, ±4) cpm for the automated conditions. The 95% limits of agreement between the manual and the automated conditions for far and near distances were poor: (−18, 12) and (−15, 3). During the hybrid unpredictable condition, the response time and accommodative response parameters were significantly (p < 0.05) larger for accommodation than disaccommodation responses for high accommodative demands only. The response times during the transitions 0.17/2.17 D and 0.50/4.50 D appeared to be indistinguishable between the hybrid unpredictable and the conventional predictable automated tests. Conclusions: The automated accommodative facility test does not agree with the manual flipper test results. Operator delays in flipping the lens may account for these differences. This novel test, using unpredictable stimuli, provides a more comprehensive examination of accommodative dynamics than conventional manual accommodative facility tests. Unexpectedly, the unpredictability of the stimulus did not to affect accommodation dynamics. Further studies are needed to evaluate the sensitivity of this novel hybrid technique on individuals with accommodative anomalies. [ABSTRACT FROM AUTHOR]