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Electrochromic devices (ECDs) have attracted substantial attention on account of their unique characteristics and prosperous applications. However, their monotonous color modification remains a momentous challenge that significantly restricts their application scope. Integrating structural colors that arise from the interaction between light and periodic micro/nanostructures with electrochromic materials (ECMs) turns out to be an effective approach to enhancing the comprehensive performance of ECDs more than the coloration effectiveness. This review provides an overview on the recent burgeoning development of structural color ECDs regarding strategies and applications. The performance parameters of ECDs and physical principles regarding the generation of structural colors are introduced. Then, strategies that introduce structural colors into ECDs are discussed according to the category of chromogenic micro/nanostructures, namely, gratings, (single‐layer and multilayer) thin films, photonic crystals, plasmonic metasurfaces, and composite structures. The current state‐of‐the‐art research activities of structural color ECDs for display application including segmented and pixelated devices are also presented. Additionally, the future perspective of structural color ECDs with respect of major challenges and potential solutions is proposed. [ABSTRACT FROM AUTHOR]

Tomatoes are an important fruit consumed worldwide. Within protected cultivation environments, artificial light using energy-efficient light-emitting diodes can be applied in tomato production as an effective way to improve productivity and nutritional value. Several studies have investigated the effects of supplementing artificial light on various aspects of tomato growth, encompassing flowering, fruit development, ripening, and nutritional composition. However, the outcomes of previous studies offer inconclusive insights into whether the observed impacts on tomato growth have resulted from the provision of additional photons or discrepancies in the spectral distribution of light during artificial light supplementation. Within this context, this study aimed to specifically explore the independent effects of monochromatic blue and red light, along with their dichromatic mixture (blue + red), on fruit growth and nutrient accumulation in comparison with multispectral white light. These four different light treatments were implemented after anthesis under the same photosynthetic photon flux density to mitigate possible variabilities arising from different light intensities and originating during the vegetative growth stage. As a result, under the same light intensity conditions, red and blue + red light irradiance during the reproductive growth stage delayed fruit ripening by up to 4.33 days compared to white light. Regarding fruit productivity, the fresh weight of fully ripe tomato fruit in the blue, red, or blue + red light treatment groups was not different from that in the white-light treatment group, whereas the blue light treatment significantly reduced the number of fruits in the plant. Finally, nutrient content, including soluble sugars, lycopene, and β-carotene, significantly increased by 10.0%, 27.1%, and 65.2%, respectively, in the blue compared to the white light-irradiated group. This study demonstrated that the application of distinct light spectra during the reproductive growth phase could have varying impacts on tomato fruit development and nutrient accumulation. By integrating our findings with results from prior studies, a more efficient light intervention strategy could be developed to effectively regulate traits of tomato fruit within an indoor production system. [ABSTRACT FROM AUTHOR]

Dynamic optical metasurfaces with ultrafast temporal response, i.e., spatiotemporal optical metasurfaces, provide attractive solutions and open fascinating perspectives for modern highly integrated optics and photonics. In this work, electro-optically controlled optical metasurfaces operating in reflection and utilizing resonant waveguide mode excitation are demonstrated from the viewpoint of free-space propagating light modulation. The modulation of reflected light power with superior characteristics in comparison with prior research is achieved by identifying a suitable low-loss waveguide mode and exploiting its resonant excitation. The electro-optic Pockels effect in a 300 nm-thick lithium niobate (LN) film sandwiched between a continuous thick gold film and an array of gold nanostripes, serving also as control electrodes, is exploited to realize fast and efficient light modulation. The fabricated compact (active area

Abstract The increasing demand for the multidimensional and dynamic control of light has spurred the development of stimuli‐responsive, reconfigurable, and programmable optical systems. Liquid crystals (LCs), which combine liquid‐like stimuli‐responsiveness and crystal‐like orientational ordering, have emerged as highly appealing soft materials. Owing to their exceptional optical performance and programmable functionalities, they are becoming incredibly important materials in active planar optics and photonics. Additionally, silk proteins, luminescent materials, and metasurfaces exhibit dynamic optical properties, enabling remarkable multifunctional applications. This review focuses on the advancements in stimuli‐responsive materials, including LCs, silk proteins, luminescent materials, and active metasurfaces as well as some of these materials paired with LCs. Their attractive tunable applications in optics and photonics, along with the great potential for the future development of active optical systems, are also emphasized.

Improving the quality of wavefront shaping (WFS) is a major problem of anti-scattering optical information transmission in the perturbation environment. To tackle this issue, we propose a simple and robust method, named Point Guard algorithm (PGA), to manipulate the optical interference by encoding the digital micromirror device (DMD). The PGA method is inspired by the movement strategies of Point Guard (PG) in professional basketball association. Compared with the most popular method genetic algorithm (GA), the proposed PGA method has a stronger anti-perturbation capacity. In the experiment, the scattering medium consists of ground glass and polystyrene microspheres (PS) suspended in deionized water, and the movement of microspheres is used to cause a perturbation. It is found that PGA still has a better modulation quality when the suspension is too thick to see the ballistic light. PGA puts a new perspective in applications such as optogenetics and biomedical imaging in complex environment.

On-chip optical communications are in increasingly demand for low-loss, small-footprint and power-efficient waveguiding solutions in the telecom band. However, most integrated optical circuits suffer from high propagation loss and low integration degree. Through manipulating the valley-dependent topological phase of light, we have experimentally demonstrated both robust optical transport and electrical modulation of lightwaves at telecom wavelengths in the valley photonic crystals. With the adoption of valley kink states, the 25 Gbit/s optical signal at 1550 nm is successfully transmitted through a highly twisted interface. Furthermore, an extreme high data rate of 100 Gbit/s is demonstrated with such topological waveguide by wavelength division multiplexing. The electrical tunability of the topological modulators based on thermo-optic effect is also verified, opening a novel route towards active valley kink photonic devices. Our study shows a great possibility of making use of the topological protection in building up high-speed datalinks on a chip.

As the vital elements for building environments, windows are utilized to bring light as well as thermal irradiation into the interior places and afford the medium for the communication between the interior and exterior of buildings. Liquid crystal (LC)‐based smart windows, which are mainly made of LC materials or polymer/LC composites, can dynamically modulate light transmittance and regulate the heat radiation entering buildings from the sun via the orientation variation of the LC molecules. Such smart windows play an important role in intelligent buildings and building energy conservation, which contributes to providing a more comfortable and low‐energy‐consumption living environment for mankind. In this review, recent progress in LC‐based smart windows of each category is overviewed. New materials, new ideas, and new methods to improve the performance of conventional LC‐based smart windows and create novel smart window technologies are outlined. Different advanced LC‐based smart window technologies, including electrochromism, thermochromism, photochromism, humidity‐triggered chromism, mechanical self‐powered technique, and dynamic infrared regulating mechanisms, are discussed systematically. The applications of LC‐based smart windows in indoor illumination/privacy protection switching, human‐machine interaction, and thermal regulation for intelligent buildings are highlighted. Last, the challenges and perspectives of LC‐based smart windows are also provided. [ABSTRACT FROM AUTHOR]

A series of (CH3NH 3) 2- x Cs x AgBiBr 6 films (x =0, 0.1, 0.2, 0.3, 0.4) were fabricated on ITO/glass substrates through the sol-gel method. 15 % Cs doping (x =0.3) was the optimal condition for enhancing the film quality and achieving nonvolatile bipolar resistive switching (BRS) performance in the devices. The on/off ratio in the (CH 3 NH 3) 1.7 Cs 0.3 AgBiBr 6 (Cs-MAABB-3)-based RS device reached 7.7×104, high and low resistance states were maintained for over 104 s. Under different light intensities with a wavelength of 430 nm, six distinct resistance states were recorded at −0.3 V in the Au/Cs-MAABB-3/ITO/glass device. These multilevel states remained after 5000 s and 650 cycles, indicating the excellent retention and endurance of multilevel RS memory in the Au/Cs-MAABB-3/ITO/glass device. The RS behavior in this device followed the trap-controlled space charge-limited current and conductive filament models. Cs-doping increased the concentration of intrinsic vacancies appropriately, leading to a more prominent RS effect. With varying intensities of illumination, the change of Schottky-like barrier at the Au/Cs-MAABB-3 interface, modulated by the photo-induced carriers, affected the multilevel resistance states in the device. The excellent multilevel RS performance was observed for the first time in the Cs-MAABB-3-based device. It presents broad possibilities for improving high-density memory in lead-free halide double perovskite-based devices. [Display omitted] • The 15% Cs-doping at the A-site could improve the flatness and density of (CH 3 NH 3) 2 AgBiBr 6 (MAABB) film. • Retention, endurance and the ON/OFF ratio in the 15% Cs doped MAABB (Cs-MAABB-3)-based RS memory were enhanced substantially. • Six levels of resistance states were exhibited in the Au/Cs-MAABB-3/ITO/glass device with different intensities of light. •.RS behavior was controlled by SCLC and CF models in the Cs-MAABB-3 layer under optical and electric fields. •.Reversible change in the Schttky barrier at the Au/Cs-MAABB-3 interface was also attributed to the RS behavior under light. [ABSTRACT FROM AUTHOR]

Tomatoes are an important fruit consumed worldwide. Within protected cultivation environments, artificial light using energy-efficient light-emitting diodes can be applied in tomato production as an effective way to improve productivity and nutritional value. Several studies have investigated the effects of supplementing artificial light on various aspects of tomato growth, encompassing flowering, fruit development, ripening, and nutritional composition. However, the outcomes of previous studies offer inconclusive insights into whether the observed impacts on tomato growth have resulted from the provision of additional photons or discrepancies in the spectral distribution of light during artificial light supplementation. Within this context, this study aimed to specifically explore the independent effects of monochromatic blue and red light, along with their dichromatic mixture (blue + red), on fruit growth and nutrient accumulation in comparison with multispectral white light. These four different light treatments were implemented after anthesis under the same photosynthetic photon flux density to mitigate possible variabilities arising from different light intensities and originating during the vegetative growth stage. As a result, under the same light intensity conditions, red and blue + red light irradiance during the reproductive growth stage delayed fruit ripening by up to 4.33 days compared to white light. Regarding fruit productivity, the fresh weight of fully ripe tomato fruit in the blue, red, or blue + red light treatment groups was not different from that in the white-light treatment group, whereas the blue light treatment significantly reduced the number of fruits in the plant. Finally, nutrient content, including soluble sugars, lycopene, and β-carotene, significantly increased by 10.0%, 27.1%, and 65.2%, respectively, in the blue compared to the white light-irradiated group. This study demonstrated that the application of distinct light spectra during the reproductive growth phase could have varying impacts on tomato fruit development and nutrient accumulation. By integrating our findings with results from prior studies, a more efficient light intervention strategy could be developed to effectively regulate traits of tomato fruit within an indoor production system.

Cyanobacteria are microorganisms that are well-adapted to sudden changes in their environment, namely to light conditions. This has allowed them to develop mechanisms for photoprotection, which encompass alteration in pigment composition. Therefore, light modulation appears to be a suitable strategy to enhance the synthesis of specific pigments (e.g., phycocyanin) with commercial interest, in addition to conveying a more fundamental perspective on the mechanisms of acclimatization of cyanobacterium species. In this study, Synechocystis salina was accordingly cultivated in two light phase stages: (i) white LED, and (ii) shift to distinct light treatments, including white, green, and red LEDs. The type of LED lighting was combined with two intensities (50 and 150 µmolphotons·m−2·s−1). The effects on biomass production, photosynthetic efficiency, chlorophyll a (chl a) content, total carotenoids (and profile thereof), and phycobiliproteins (including phycocyanin, allophycocyanin, and phycoerythrin) were assessed. White light (under high intensity) led to higher biomass production, growth, and productivity; this is consistent with higher photosynthetic efficiency. However, chl a underwent a deeper impact under green light (high intensity); total carotenoids were influenced by white light (high intensity); whilst red treatment had a higher effect upon total and individual phycobiliproteins. Enhanced PC productivities were found under modulation with red light (low intensities), and could be achieved 7 days earlier than in white LED (over 22 days); this finding is quite interesting from a sustainability and economic point of view. Light modulation accordingly appears to be a useful tool for supplementary studies pertaining to optimization of pigment production with biotechnological interest. [ABSTRACT FROM AUTHOR]

Subwavelength dielectric resonators have been demonstrated to provide an authentic platform to excite high-Q resonances in flat optics. Here, we present a strategy to modulate the high-Q resonances electrically using graphene. In the proposed strategy, the high-Q resonance is invoked through the use of a lateral guided-mode resonance that is spectrally aligned with a vertical thin film interference, while graphene is employed to engineer the overall absorption rate. This configuration allows for near unity modulations in both the transmission and the reflection simultaneously. Theoretical analysis shows that the excitation of the high-Q guided-mode resonance is dictated by the electrically tunable interband absorption in graphene while the radiative coupling channel remains intact. In particular, it is shown that the electrical modulation of the high-Q guided-mode resonance facilitates remarkably efficient light modulation without being limited by the graphene quality.

The threat of cascading damage to downstream components caused by the light modulation intensification of laser repaired morphology on the surface of fused silica optics cannot be ignored in high-power laser systems. This paper uses the angular spectrum diffraction theory based on the analysis of repaired surface morphology of CO2 laser rapid ablation mitigation to study the influence of different repaired morphologies on the downstream 355 nm laser transmission. Studies show that the arc-shaped laser processing lines on the repaired surface are formed by the residual height superposition of the material after laser scanning of two adjacent layers, and the short-pulse laser can substantially suppress the heat-affected zone of the repaired area. The off-axis ring caustic and on-axis hotspot are sequentially generated in the downstream modulated light fields of the conical repaired sites with different diameters. A secondary peak with modulation larger than 3 emerges downstream of the modulation curve. Meanwhile, the maximum modulation and the secondary peak increase with the diameter and cone angle of the repaired site, and the position of the secondary peak appears farther away from the rear surface. The modulations of three repaired sites with cone angles of 15°, 20°, and 25° can finally be stabilized below 3. Overall, the downstream optics should be installed far away from the positions where the maximum modulation and the secondary peak emerge. Additionally, the maximum value and the secondary peak of the downstream light modulation of double repaired sites are larger than that of the single repaired site, and both rise as the repaired sizes increase. Thus, large-scale and large-size repairing of multiple surface damages in the same area should be avoided in the laser repairing of fused silica. [ABSTRACT FROM AUTHOR]

Single-color reflectrometry is a sensitive and robust detection method in optical biosensor applications, for example for bioanalysis. It is based on the interference of reflected monochromatic radiation and is label free. We present a novel setup for single-color reflectometry based on the patented technology of Berner et al. from 2016. Tilting areas of micro-mirrors allow us to encode the optical reflection signal of an analyte and reference channel into a particular carrier frequency with the amplitude being proportional to the local reflection. Therefore, a single photodiode is sufficient to collect the signals from both channels simultaneously. A 180∘ phase shift in the tilt frequency of two calibrated micro-mirror areas leads to a superposition of the analyte and reference signal which enables an efficient reduction of the baseline offset and potential baseline offset drift. A performance test reveals that we are able to detect changes of the refractive index n down to Δn < 0.01 of saline solutions as regents. A further test validates the detection of heterogeneous binding interaction. This test compromises immobilized testosterone-bovine serum albumin on a three-dimensional layer of biopolymer as ligand and monoclonal anti-testosterone antibodies as analyte. Antibody/antigen binding induces a local growth of the biolayer and change in the refractive index, which is measured via the local change of the reflection. Reproducible measurements enable for the analysis of the binding kinetics by determining the affinity constant KA = 1.59 × 10− 7 M− 1. In summary, this work shows that the concept of differential Fourier spotting as novel setup for single-color reflectometry is suitable for reliable bioanalysis. [ABSTRACT FROM AUTHOR]

Quantitative detections of proteins for single cells have made great contributions to tumor heterogeneity and immune variance while effective tools of measuring single-cell intracellular proteins are under developments. This study reported a flow cytometer based on constriction microchannel and light modulation, which was capable of quantifying intracellular proteins for single cells with high resolution. Cells tagged with fluorescein labelled antibodies were squeezed into the constriction microchannel as either the calibration or detection structure where a light source with a carrier wave was used for fluorescent modulation, which was further demodulated into the low-frequency domain and translated into numbers of single-cell proteins. In platform characterization, the inclusion of light modulation was shown to effectively improve the detection resolution from ~1000 intracellular proteins per cell without modulation to ~100 intracellular proteins per cells with modulation. As demonstrations, expressions of mutant p53 or phosphorylated p53 from tens of thousands of single T47D and/or A431 cells were quantitatively measured by the microfluidic quantitative flow cytometer, which were 1.78 ± $0.96 \times10$ 5 mutant p53 per cell for T47D cells (${N}_{c} =10\,315$), 1.99 ± $1.49\times10$ 5 mutant p53 per cell for A431 cells (${N}_{c} =15\,665$), and 6.34 ± $7.50\times10$ 3 phosphorylated p53 per cell for A431 cells treated with doxorubicin (${N}_{c} =12\,812$). In conclusion, the inclusion of light modulation can effectively decrease electrical and optical noises and therefore improve detection resolution in microfluidic quantitative flow cytometry. [ABSTRACT FROM AUTHOR]

In this work, the authors demonstrate the control of quality factor (Q‐factor) is laterally coupled vertical cavities. A 3 μm‐side‐length square cavity directly connected to a 1.5 μm‐width, 10 μm‐length Fabry–Perot (FP) cavity has been fabricated and measured. Dynamic tuning of the Q‐factor has been successfully observed by bringing the square cavity and FP cavity into resonance. The vertical‐cavity‐based Q‐factor control scheme provides a new choice for the modulation of light and holds potentials for applications associated with optical information processing.

Undoubtedly, optical choppers are one of the oldest and most common light modulation tools, which still have many applications in optoelectronic devices such as guidance systems, opto-mechanical mouses, and photoacoustic systems. In this study, transmission function of a chopper with circular shape apertures was studied whereas the distribution of the incident beam was considered Gaussian. A mathematical model was obtained for transmitted signals through the circular chopper. Studies were done for different ratios of apertures diameter to the beam cross section and the effect of this ratio on the profile of output pulses were studied. Finally, this model was validated by a simple optical experiment. This model can be easily extended for any laser beam profiles such as top hat beams and can be a leading method in optical devices and techniques based on the use of chopper wheels. • A new theoretical method for modeling output pulses from a chopper wheel with circular shape apertures was presented. • A new geometry of the problem was redefined which can obtain the transmission function with a very high accuracy. • Numerical studies were carried out for different ratios of apertures diameter to the beam cross section. • This model was easily extended for both the Gaussian and top hat beams. • Finally, this model has been confirmed through an optical experiment. [ABSTRACT FROM AUTHOR]

The modulation and spectral characteristics of self-organized ensembles of nematic domains with the disclination lines non-aligned and aligned in a magnetic field have been studied using an electric field. The obtained experimental voltage dependences of the light transmission agree well with the dependences calculated using the model considerations. These dependences have been compared with the electro-optical characteristics of a homogeneous planar nematic layer. The amplitude component of the optical transmission determined by light scattering and the oscillating component caused by the phase modulation have been examined. The effect of the spectral dispersion of transmission on the electro-optical characteristics of domain ensembles has been evaluated. [Display omitted] • SEND is a promising material for light modulators. • Light modulation in SEND occurs due to interference effect in the absence of polarizers. • Light scattering in SEND is significantly reduced when disclination lines are ordered in a magnetic field. • The spectral dispersion of SEND light transmission is controlled by electrical voltage. [ABSTRACT FROM AUTHOR]

The aim of the study was observation of the effect of light modulation on blood testosterone levels and libido in male American mink. The study was performed on 64 Black Velvet male mink on a farm located in the north-west of Poland. Day length was modified using artificial lighting placed above mink cages. Two variants of lighting programs were applied to males: (I) from 8 of February and (II) from 12 of February. In order to measure blood testosterone concentration samples were collected from males of the experimental groups and the control groups (animals kept under natural light conditions). As a result of the experiment, the males subjected to extended lighting were found to have had slightly higher libido than those outside the treatment, although no strong or clear effect of lighting on the pattern of testosterone levels in male mink has been found. It remains unexplained whether slightly, non-significantly higher libido of the experimental males is related to the applied modulation of photoperiod. In order to unambiguously clarify the effect of day light modulation on the results of males sexual activity, further studies should be performed on a larger population and possibly using modified extended lighting programs.

Cyanobacteria are microorganisms that are well-adapted to sudden changes in their environment, namely to light conditions. This has allowed them to develop mechanisms for photoprotection, which encompass alteration in pigment composition. Therefore, light modulation appears to be a suitable strategy to enhance the synthesis of specific pigments (e.g., phycocyanin) with commercial interest, in addition to conveying a more fundamental perspective on the mechanisms of acclimatization of cyanobacterium species. In this study, Synechocystis salina was accordingly cultivated in two light phase stages: (i) white LED, and (ii) shift to distinct light treatments, including white, green, and red LEDs. The type of LED lighting was combined with two intensities (50 and 150 µmolphotons·m−2·s−1). The effects on biomass production, photosynthetic efficiency, chlorophyll a (chl a) content, total carotenoids (and profile thereof), and phycobiliproteins (including phycocyanin, allophycocyanin, and phycoerythrin) were assessed. White light (under high intensity) led to higher biomass production, growth, and productivity; this is consistent with higher photosynthetic efficiency. However, chl a underwent a deeper impact under green light (high intensity); total carotenoids were influenced by white light (high intensity); whilst red treatment had a higher effect upon total and individual phycobiliproteins. Enhanced PC productivities were found under modulation with red light (low intensities), and could be achieved 7 days earlier than in white LED (over 22 days); this finding is quite interesting from a sustainability and economic point of view. Light modulation accordingly appears to be a useful tool for supplementary studies pertaining to optimization of pigment production with biotechnological interest.

The reversible metal electrodeposition device (RMED) is a novel electrochromic application that utilizes the appearance and disappearance of a metal layer to achieve spectrum control. A thin metal film with a thickness of a few tens of nanometers would be highly reflective in the visible and infrared region, making it an ideal material to achieve light and heat modulation. Because of their outstanding spectrum control ability, RMEDs can be applied to displays, smart windows, and thermal camouflage. However, as is the case with many other electrochromic devices, difficulties in device enlargement pose significant challenges to the application of RMEDs. Herein, an overview of the milestone advances of RMEDs is provided, with a focus on their application as smart windows, which is the most extensively studied topic. Recent attempts to improve their open‐circuit stability and designs for device enlargement are highlighted. Finally, insight into the remaining challenges and future prospects in this field is provided. [ABSTRACT FROM AUTHOR]

A very large dynamic optical reflection modulation from a simple unpatterned layered stack of phase‐change material ultra‐thin films is experimentally demonstrated. Specifically, this work demonstrates that properly designed systems comprising deeply subwavelength GeSbTe (GST) films, a dielectric spacer, and a metallic mirror produce a dynamic modulation of light in the near‐infrared from very strong reflection (up to R≈80%) to perfect absorption (A>99.995%) by simply controlling the crystalline state of the phase‐change material. While the amplitude of modulation experimentally reaches an optical contrast higher than 104, intermediate levels of reflection in between extreme values can also be actively encoded, corresponding to partial crystallization of the GST layer. Several layered system designs are further explored and guidelines are provided to tailor the efficient wavelength range, the angle of operation, and the degree of crystallization leading to perfect absorption. [ABSTRACT FROM AUTHOR]

Liquid-liquid interfaces hold the potential to serve as versatile platforms for dynamic processes, due to their inherent fluidity and capacity to accommodate surface-active materials. This study explores laser-driven actuation of liquid-liquid interfaces with and without loading of gold nanoparticles and further exploits the laser-actuated interfaces with nanoparticles for tunable photonics. Upon laser exposure, gold nanoparticles were rearranged along the interface, enabling the reconfigurable, small-aperture modulation of light transmission and the tunable lensing effect. Adapting the principles of optical and optothermal tweezers, we interpreted the underlying mechanisms of actuation and modulation as a synergy of optomechanical and optothermal effects. Our findings provide an analytical framework for understanding microscopic interfacial behaviors, contributing to potential applications in tunable photonics and interfacial material engineering.

In this work, the authors demonstrate the control of quality factor (Q‐factor) is laterally coupled vertical cavities. A 3 μm‐side‐length square cavity directly connected to a 1.5 μm‐width, 10 μm‐length Fabry–Perot (FP) cavity has been fabricated and measured. Dynamic tuning of the Q‐factor has been successfully observed by bringing the square cavity and FP cavity into resonance. The vertical‐cavity‐based Q‐factor control scheme provides a new choice for the modulation of light and holds potentials for applications associated with optical information processing. [ABSTRACT FROM AUTHOR]

The threshold switching (TS) phenomenon in memristors has drawn great attention for its versatile applications in selectors, artificial neurons, true random number generators, and electronic integrations. The transition between nonvolatile resistive switching and volatile TS modes can be realized by doping, varying annealing and voltage sweeping conditions, or imposing different compliance current. Here, a strategy is reported to achieve such transition by the noninvasive UV light stimulus based on InP/ZnS quantum dot (QD) memristor. The core–shell InP/ZnS QDs with quasi‐type II band alignment ensures photoexcited electrons localized in InP core, photoexcited hole state distributed in the outer shell, and subsequent lifetime controlling of conductive filament under light irradiation. Systematic mechanism investigations indicate that UV photogenerated holes are accumulated on the surface of the QD film, which is consistent with rapid transfer of photogenerated holes in the core–shell InP/ZnS structure. Based on the light‐modulated effect, a reconfigurable 9 × 9 visual data storage array with a key pattern and a simple leaky integrate‐and‐fire circuit are constructed. These results suggest the potential of direct optical modulation of memory mode through energy band engineering, leading to future optoelectronic and electronic device for the implementation of neuromorphic visual system and artificial neural networks. [ABSTRACT FROM AUTHOR]

Light-modulated lead-free perovskites-based memristors, combining photoresponse and memory, are promising as multifunctional devices. In this work, lead-free double perovskite Cs2AgBiBr6 films with dense surfaces and uniform grains were prepared by the low-temperature sol-gel method on indium tin oxide (ITO) substrates. A memory device based on a lead-free double perovskite Cs2AgBiBr6 film, Pt/Cs2AgBiBr6/ITO/glass, presents obvious bipolar resistive switching behavior. The ROFF/RON ratio under 445 nm wavelength light illumination is ~100 times greater than that in darkness. A long retention capability (>2400 s) and cycle-to-cycle consistency (>500 times) were observed in this device under light illumination. The resistive switching behavior is primarily attributed to the trap-controlled space-charge-limited current mechanism caused by bromine vacancies in the Cs2AgBiBr6 medium layer. Light modulates resistive states by regulating the condition of photo-generated carriers and changing the Schottky-like barrier of the Pt/Cs2AgBiBr6 interface under bias voltage sweeping.

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Speed and quality of wavefront shaping (WFS) are considered to be two major challenges in anti-scattering optical information transmission. Confronted with this, a novel optimization approach, namely Point Guard algorithm (PGA), is proposed based on the movement strategies of Point Guard (PG) in professional basketball association. The PGA manipulates the optical interference by encoding the digital micromirror device (DMD). The performance of the PGA can only be affected by one parameter (boundary value, BV), and the strategy of self-adaptive updating is adopted for this parameter to accelerate the speed of searching optimal pattern. Compared with the most popular WFS method genetic algorithm (GA), the PGA improves the speed and peak-to-background ratio (PBR) of single-point focusing by a factor of 10.49 and 4.05 within 500 iterations. We also accomplish 7-point focusing and form a bright and uniform Z-shape pattern in a short optimization period. Furthermore, it is demonstrated that the PGA can quickly reconstruct the visible image information through the scattering medium. With the ability to uniquely identify its target area, the reconstructed image ensures the secure optical communication. We also experimentally demonstrate that the PGA can parallel reconstruct three images in a short optimization period without obvious cross-talk. This new method has good potential in applications such as optogenetics, optical trapping and optical information transmission in complex environment. • The anti-scattering optical information transmission is well completed with the proposed method PGA. • PGA significantly improves the speed and quality of wavefront shaping in turbid media compared with the most popular method GA. • PGA also accomplish the 7-point focusing and 3-image information parallel transmission in a short optimization period. [ABSTRACT FROM AUTHOR]

Avian eggshells are variedly coloured, yet only two pigments, biliverdin and protoporphyrin IX, are known to contribute to the dramatic diversity of their colours. By contrast, the contributions of structural or other chemical components of the eggshell are poorly understood. For example, unpigmented eggshells, which appear white to the human eye, vary in their ultraviolet (UV) reflectance, which may be detectable by birds. We investigated the proximate mechanisms for the variation in UV-reflectance of unpigmented bird eggshells using spectrophotometry, electron microscopy, chemical analyses, and experimental manipulations. We specifically tested how UV-reflectance is affected by the eggshell cuticle, the outermost layer of most avian eggshells. The chemical dissolution of the outer eggshell layers, including the cuticle, increased UV-reflectance for only eggshells that contained a cuticle. Our findings demonstrate that the outer eggshell layers, including the cuticle, absorb UV-light, probably because they contain higher levels of organic components and other chemicals, such as calcium phosphates, compared to the predominantly calcite-based eggshell matrix. These data highlight the need to examine factors other than the known pigments in studies of avian eggshell colour.

Breaking Lorentz reciprocity is one necessary condition of optical isolator design. Unidirectional wavelength-mode conversion will be realized in a time-dependent system through a short operating range. Based on plasma dispersion effect, generate space-asymmetric periodical time-space modulation on silicon waveguide, and non-reciprocal propagation is realized in the waveguide. The designed unidirectional wavelength-mode conversion waveguide demonstrated that in the forward direction, input 1.55 μ m fundamental mode light signal and then output 1.5492 μ m is of 1st-order mode, while in the backward direction, input 1.5492 μ m is of 1st-order mode light signal and then output 1.5484 μ m is of fundamental mode. Based on this non-reciprocal structure, mode conversion waveguide and two-ring resonance filters were designed then, to accomplish on-chip optical isolation. The scale of the designed isolator is 160  μ m × 60 μ m, and the isolation is 21 dB, revealing perfect application potential. [ABSTRACT FROM AUTHOR]

• The anti-scattering optical information transmission is well completed in the perturbation environment. • The proposed PGA can quickly transmit the image information in scattering light field of perturbation. • PGA put a new perspective for wavefront shaping in noise environment. Improving the quality of wavefront shaping (WFS) is a major problem of anti-scattering optical information transmission in the perturbation environment. To tackle this issue, we propose a simple and robust method, named Point Guard algorithm (PGA), to manipulate the optical interference by encoding the digital micromirror device (DMD). The PGA method is inspired by the movement strategies of Point Guard (PG) in professional basketball association. Compared with the most popular method genetic algorithm (GA), the proposed PGA method has a stronger anti-perturbation capacity. In the experiment, the scattering medium consists of ground glass and polystyrene microspheres (PS) suspended in deionized water, and the movement of microspheres is used to cause a perturbation. It is found that PGA still has a better modulation quality when the suspension is too thick to see the ballistic light. PGA puts a new perspective in applications such as optogenetics and biomedical imaging in complex environment. [ABSTRACT FROM AUTHOR]

Measuring the external quantum efficiency (EQE) of a solar cell is a standard method to gain deeper insights into its opto-electrical properties. For the case of crystalline silicon solar cells, the EQE of a solar cell is often used to assess the quality of the emitter and the passivation scheme. However, the standard EQE measurement method employs a monochromator which means that several minutes are typically needed to complete a single measurement. In academic environments this can form a bottleneck in the research output, while in industrial environments with production speeds of at least 1800 wafers/hour EQE measurements cannot be readily used. In this work, we introduce a new patented characterization tool which we call the Fast Optical Measurement System (FOMS). When using the FOMS, it becomes possible to measure the EQE of amorphous and crystalline silicon solar cells about 3 orders of magnitude faster when compared to a conventional monochromatic measurement. This means that a measurement of the full visible/near-infrared (VIS/NIR) spectrum can be done in 1–10 s, without compromising on accuracy. Additionally, the FOMS can also be used to perform ultrafast reflectance/transmittance once further add-ons to the system are implemented. This opens a path to many optical applications, also outside the photovoltaics field, where fast and accurate broadband measurements are needed. [ABSTRACT FROM AUTHOR]

The cone and Gaussian repaired damage craters are two typical morphologies induced by CO2 laser evaporation and nonevaporation technologies. The mathematical models are built for these two types of repaired craters, and the light modulation at 355 nm induced by the millimeter-scale repaired damage morphology is studied by scalar diffraction theory. The results show that the modulation of the Gaussian repaired morphology has one peak and then decreases with the increasing distance from 0 to 30 cm. While the modulation for cone repaired morphology remains stable after decreasing quickly with the increasing distance. When the horizontal radius increases, the modulation looks like a saw-tooth. However, the modulation has irregular variations for two kinds of morphologies with the increasing vertical depth. The simulated results agree well with experimental results. The horizontal and vertical dimensions, and downstream distance have different influences on the modulation. The risk of damage to downstream optical components can be suppressed to improve the stability of the optical system if the shape and size of repaired craters are well controlled and the positions of downstream optical components are selected appropriately. [ABSTRACT FROM AUTHOR]

We present a scheme in which light is modulated through coherent perfect activity. By irradiating two coherent beams from both sides to a magnetic material and controlling their relative phases, we can manipulate the output light. Through coherent perfect polarization rotation process, large polarization rotation angles can be observed, which makes possible the light modulation. It is realized that this coherent process provides the light modulation by using a very low intensity coherent light. • We have used a new (CPPR) method to modulate light. • The CPPR method has been applied to a thin magnetic slab. • Without increasing the magnetic field, polarization rotation is improved. • The role of influential parameters in modulation have been discussed. [ABSTRACT FROM AUTHOR]

Abstract Bipolar resistive switching behavior in ZnO/BiFeO 3 device is demonstrated, which can be modulated by white light at room temperature. The light-control resistive switching effect in ZnO/BiFeO 3 device shows excellent stability in the light conditions when operating external sweep voltages. The ZnO/BiFeO 3 device device can maintain superior stability over 439 cycles under the irradiation with power density of 2 mW/cm2. Based on the double-logarithm current-voltage(I-V) fitting curves, the electrons trapping and de-trapping in the Schottky-Like depletion layer in the interface of our memory cells should dominate the resistive switching behavior. This work can provide a possible mechanism for the light-control resistive switching system. Highlights • The resistive switching effect in ZnO/BiFeO 3 bilayer is reported. • The resistive switching effect in ZnO/BiFeO 3 bilayer can be modulated by white light and voltage. • The resistive switching in ZnO/BiFeO3 device device can maintain superior stability. [ABSTRACT FROM AUTHOR]