Self-polarized RGB device realized by semipolar micro-LEDs and perovskite-in-polymer films for backlight applications

In backlighting systems for liquid crystal displays,conventional red,green,and blue(RGB)light sources that lack polarization properties can result in a significant optical loss of up to 50%when passing through a polarizer.To address this inefficiency and optimize energy utilization,this study presents a high-performance device designed for RGB polarized emissions.The device employs an array of semipolar blueμLEDs with inherent polarization capabilities,coupled with mechanically stretched films of green-emitting CsPbBr3 nanorods and red-emitting CsPbI3-Cs4PbI6 hybrid nanocrystals.The CsPbBr3 nanorods in the polymer film offer intrinsic polarization emission,while the aligned-wire structures formed by the stable CsPbI3-Cs4PbI6 hybrid nanocrystals contribute to substantial anisotropic emissions,due to their high dielectric constant.The resulting device achieved RGB polarization degrees of 0.26,0.48,and 0.38,respectively,and exhibited a broad color gamut,reaching 137.2%of the NTSC standard and 102.5%of the Rec.2020 standard.When compared to a device utilizing c-plane LEDs for excitation,the current approach increased the intensity of light transmitted through the polarizer by 73.6%.This novel fabrication approach for polarized devices containing RGB components holds considerable promise for advancing next-generation display technologies.

Deep learning-assisted common temperature measurement based on visible light imaging

Real-time,contact-free temperature monitoring of low to medium range(30℃-150℃)has been extensively used in industry and agriculture,which is usually realized by costly infrared temperature detection methods.This paper proposes an alternative approach of extracting temperature information in real time from the visible light images of the monitoring target using a convolutional neural network(CNN).A mean-square error of<1.119℃was reached in the temperature measurements of low to medium range using the CNN and the visible light images.Imaging angle and imaging distance do not affect the temperature detection using visible optical images by the CNN.Moreover,the CNN has a certain illuminance generalization ability capable of detection temperature information from the images which were collected under different illuminance and were not used for training.Compared to the conventional machine learning algorithms mentioned in the recent literatures,this real-time,contact-free temperature measurement approach that does not require any further image processing operations facilitates temperature monitoring applications in the industrial and civil fields.

Finely regulated luminescent Ag-In-Ga-S quantum dots with green-red dual emission toward white light-emitting diodes

Ag-In-Ga-S(AIGS)quantum dots(QDs)have recently attracted great interests due to the outstanding optical properties and eco-friendly components,which are considered as an alternative replacement for toxic Pb-and Cd-based QDs.However,enormous attention has been paid to how to narrow their broadband spectra,ignoring the application advantages of the broadband emission.In this work,the AIGS QDs with controllable broad green-red dual-emission are first reported,which is achieved through adjusting the size distribution of QDs by controlling the nucleation and growth of AIGS crystals.Resultantly,the AIGS QDs exhibit broad dual-emission at green-and red-band evidenced by photoluminescence(PL)spectra,and the PL relative intensity and peak position can be finely adjusted.Furthermore,the dual-emission is the intrinsic characteristics from the difference in confinement effect of large particles and tiny particles confirmed by temperature-dependent PL spectra.Accordingly,the AIGS QDs(the size consists of 17 nm and 3.7 nm)with 530 nm and 630 nm emission could successfully be synthesized at 220°C.By combining the blue light-emitting diode(LED)chips and dual-emission AIGS QDs,the constructed white light-emitting devices(WLEDs)exhibit a continuous and broad spectrum like natural sunlight with the Commission Internationale de l’Eclairage(CIE)chromaticity coordinates of(0.33,0.31),a correlated color temperature(CCT)of 5425 K,color rendering index(CRI)of 90,and luminous efficacy of radiation(LER)of 129 lm/W,which indicates that the AIGS QDs have huge potential for lighting applications.

Effect of artificial natural light on the development of myopia among primary school-age children in China:a three-year longitudinal study

AIM:To assess the efficacy of artificial natural light in preventing incident myopia in primary school-age children.METHODS:This is a prospective,randomized control,intervention study.A total of 1840 students from 39 classes in 4 primary schools in Foshan participated in this study.The whole randomization method was adopted to include classes as a group according to 1:1 randomized control.Classrooms in the control group were illuminated by usual light,and classrooms in the intervention group were illuminated by artificial natural light.All students received uncorrected visual acuity and best-corrected visual acuity measurement,non-cycloplegic autorefraction,ocular biometric examination,slit lamp and strabismus examination.Three-year follow-up,the students underwent same procedures.Myopia was defined as spherical equivalent refraction≤-0.50 D and uncorrected visual acuity<20/20.RESULTS:There were 894 students in the control group and 946 students in the intervention group with a mean±SD age of 7.50±0.53y.The three-year cumulative incidence rate of myopia was 26.4%(207 incident cases among 784 eligible participants at baseline)in the control group and 21.2%(164 incident cases among 774 eligible participants at baseline)in the intervention group[difference of 5.2%(95%CI,3.7%to 10.1%);P=0.035].There was also a significant difference in the three-year change in spherical equivalent refraction for the control group(-0.81 D)compared with the intervention group[-0.63 D;difference of 0.18 D(95%CI,0.08 to 0.28 D);P<0.001].Elongation of axial length was significantly different between in the control group(0.77 mm)and the intervention group[0.72 mm;difference of 0.05 mm(95%CI,0.01 to 0.09 mm);P=0.003].CONCLUSION:Artificial natural light in the classroom of primary schools can result in reducing incidence rate of myopia during a period of three years.

学术期刊引领建构中国自主知识体系的实践探索——以Light学术出版中心为例

学术期刊作为中国自主知识体系的建构者之一,在建构中国自主知识体系中发挥着重要作用。以Light学术出版中心为例,分析其通过自主办刊、国际交流、创新性学术活动和新技术应用等举措不断实践和探索,发挥学术期刊的多维度引领作用。在引领中国自主知识体系建构中,学术期刊从业者应通过平衡发展学科影响力,树立办刊者的自觉性,把握国际交流合作中的尺度,优化现有资源和评价体系等具体策略,以创新和实践持续推动中国自主知识体系的建构和发展。

Lightweight Cross-Modal Multispectral Pedestrian Detection Based on Spatial Reweighted Attention Mechanism

Multispectral pedestrian detection technology leverages infrared images to provide reliable information for visible light images, demonstrating significant advantages in low-light conditions and background occlusion scenarios. However, while continuously improving cross-modal feature extraction and fusion, ensuring the model’s detection speed is also a challenging issue. We have devised a deep learning network model for cross-modal pedestrian detection based on Resnet50, aiming to focus on more reliable features and enhance the model’s detection efficiency. This model employs a spatial attention mechanism to reweight the input visible light and infrared image data, enhancing the model’s focus on different spatial positions and sharing the weighted feature data across different modalities, thereby reducing the interference of multi-modal features. Subsequently, lightweight modules with depthwise separable convolution are incorporated to reduce the model’s parameter count and computational load through channel-wise and point-wise convolutions. The network model algorithm proposed in this paper was experimentally validated on the publicly available KAIST dataset and compared with other existing methods. The experimental results demonstrate that our approach achieves favorable performance in various complex environments, affirming the effectiveness of the multispectral pedestrian detection technology proposed in this paper.

RelightGAN:基于生成对抗网络的暗图像增强

针对成像设备在夜间或低光环境下拍摄图像出现光照不足、对比度低和信息丢失等问题.设计基于生成对抗网络(generative adversarial network,GAN)改进的暗图像增强网络RelightGAN,该网络包含两个判别器和一个生成器,由两组对抗损失和循环损失共同约束生成器,使之生成更优异的光照层.为增强网络训练过程中对图像细节信息的恢复能力,引入残差网络解决梯度消失问题,同时引入混合注意力机制CBAM结构,提升生成器对图像中重要信息和结构的关注度增强网络表达能力.通过与其他暗图像增强网络增强后的暗图像进行对比,Relight-GAN网络增强后的图像,相较于其他网络峰值信噪比(PSNR)值提高了12.81%,结构相似度(SSIM)值提高了5.95%.实验结果表明RelightGAN网络结合了传统算法和神经网络的优点,实现了暗场景图像的增强,提高了图像可见度.

Enhancing performance of inverted quantum-dot light-emitting diodes based on a solution-processed hole transport layer via ligand treatment

The performance of inverted quantum-dot light-emitting diodes(QLEDs)based on solution-processed hole transport layers(HTLs)has been limited by the solvent-induced damage to the quantum dot(QD)layer during the spin-coating of the HTL.The lack of compatibility between the HTL’s solvent and the QD layer results in an uneven surface,which negatively impacts the overall device performance.In this work,we develop a novel method to solve this problem by modifying the QD film with 1,8-diaminooctane to improve the resistance of the QD layer for the HTL’s solvent.The uniform QD layer leads the inverted red QLED device to achieve a low turn-on voltage of 1.8 V,a high maximum luminance of 105500 cd/m2,and a remarkable maximum external quantum efficiency of 13.34%.This approach releases the considerable potential of HTL materials selection and offers a promising avenue for the development of high-performance inverted QLEDs.

Impedance spectroscopy for quantum dot light-emitting diodes

Impedance spectroscopy has been increasingly employed in quantum dot light-emitting diodes(QLEDs)to investigate the charge dynamics and device physics.In this review,we introduce the mathematical basics of impedance spectroscopy that applied to QLEDs.In particular,we focus on the Nyquist plot,Mott-Schottky analysis,capacitance-frequency and capacitance-voltage characteristics,and the d C/d V measurement of the QLEDs.These impedance measurements can provide critical information on electrical parameters such as equivalent circuit models,characteristic time constants,charge injection and recombination points,and trap distribution of the QLEDs.However,this paper will also discuss the disadvantages and limitations of these measurements.Fundamentally,this review provides a deeper understanding of the device physics of QLEDs through the application of impedance spectroscopy,offering valuable insights into the analysis of performance loss and degradation mechanisms of QLEDs.

Plasma optics:A perspective for high-power coherent light generation and manipulation

Over the last two decades,the importance of fully ionized plasmas for the controlled manipulation of high-power coherent light has increased considerably.Many ideas have been put forward on how to control or change the properties of laser pulses such as their frequency,spectrum,intensity,and polarization.The corresponding interaction with a plasma can take place either in a self-organizing way or by prior tailoring.Considerable work has been done in theoretical studies and in simulations,but at present there is a backlog of demand for experimental veri-fication and the associated detailed characterization of plasma-optical elements.Existing proof-of-principle experiments need to be pushed to higher power levels.There is little doubt that plasmas have huge potential for future use in high-power optics.This introduction to the special issue of Matter and Radiation at Extremes devoted to plasma optics sets the framework,gives a short historical overview,and briefly describes the various articles in this collection.

Optical chirality induced by spin–orbit interaction of light in a tightly focused Laguerre–Gaussian beam

Optical chirality is one of the important and fundamental dynamic properties of light besides energy, momentum,and angular momentum. The quantification of electromagnetic chirality has been conceptualized only recently. Now, it is well known that for paraxial plane waves of light, the optical chirality is proportional to the ellipticity of the polarization ellipse, i.e., completely independent of the phase distribution. Here it is shown that optical vortex and state of polarization of the source paraxial field both have contributions to the optical chirality of the nonparaxial field generated by tightly focused Laguerre–Gaussian(LG) beam, which is in Stark contrast to the paraxial plane wave of light known from classical optics. The physical reason is the redistribution of local electromagnetic polarization in three dimensions associated with spin–orbit interaction.

Mid-infrared lightly Er^(3+)-doped CaF_(2)laser under acousto–optical modulation

A 1.7-at.%Er:CaF_(2)crystal was synthesized by temperature gradient method.The Er:CaF_(2)crystal was applied in acousto-optically Q-switched laser at mid-infrared region for the first time.Using a Te O_(2)-based crystal as Q-switcher,we obtained a laser diode(LD)end-pumped Er:CaF_(2)laser with the highest single pulse energy up to 0.49 mJ and maximum peak power of 0.56 kW under 6.34-W absorbed pump power.The implication of these results is that the low-doped Er:CaF_(2)crystal exhibits promising optical properties in solid-state lasers.

人LIGHT基因的克隆及其重组腺病毒载体的构建

目的 克隆人ＬＩＧＨＴ基因，构建其重组腺病毒载体，以研究ＬＩＧＨＴ过表达与腺病毒感染对细胞生长的影响。方法用ＲＴ－ＰＣＲ法从人外周血单个核细胞（ＰＢＭＣ）中克隆人的ＬＩＧＨＴ全长基因。将ＬＩＧＨＴ ｃＤＮＡ克隆到穿棱载体ｐＡｄＴｒａｃｋ－ＣＭＶ－ＬＩＧＨＴ重组质粒中，经酶切线性化后，将重组质粒ｐＡｄＴｒａｃｋ－ＣＭＶ－ＬＩＧＨＴ和骨架质粒ｐＡｄＥａｓｙ－１，以电穿孔法共转染大肠杆菌ＢＪ５１８３，获得重组腺病毒质粒。最后，将线性化的重组腺病毒质粒转染２９３细胞包装获得重组腺病毒，用荧光显微镜、ＰＣＲ及Ｗｅｓｔｅｒｎ ｂｌｏｔ分析ＬＩＧＨＴ基因的表达。 结果 用ＲＴ－ＰＣＲ法从人的ＰＢＭＣ中，扩增出７２３ ｂｐ的ｃＤＮＡ，测序证实为人ＬＩＧＨＴ基因。荧光显微镜、ＰＣＲ及Ｗｅｓｔｅｒｎ ｂｌｏｔ证实，ＬＩＧＨＴ重组腺病毒可感染２９３细胞，并在２９３细胞内进行有效的复制。结论成功地克隆了人ＬＩＧＨＴ基因，并构建了其重组腺病毒载体，为进一步研究ＬＩＧＨＴ基因的功能提供了条件。

新时代科技期刊品牌化、集群化发展探讨--以Light品牌期刊集群为例

Light品牌期刊集群通过借鉴国内外典型出版机构的管理机制和办刊模式,立足国内,放眼国际,在创新管理机制、优化学科布局、组约顶尖成果、开创特色栏目、打造科技媒体、创新服务模式等方面进行探索与实践,走出了一条具有中国特色和国际影响力的品牌化、集群化发展道路。面对新时代品牌化、集群化发展面临的困难和挑战,我国科技期刊应从品牌刊群建设、数字平台建设和人才队伍建设方面开拓创新,走出一条具有中国特色和国际影响力的品牌刊群之路,以实现我国科技期刊高质量、跨越式发展。

Regulating Charge and Exciton Distribution in High-Performance Hybrid White Organic Light-Emitting Diodes with n-Type Interlayer Switch

The interlayer(IL) plays a vital role in hybrid white organic light-emitting diodes(WOLEDs); however,only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time,has been demonstrated to achieve a high efficiency, high color rendering index(CRI), and low voltage trade-off.The device exhibits a maximum total efficiency of 41.5 lm W^(-1), the highest among hybrid WOLEDs with n-type ILs. In addition, high CRIs(80–88) at practical luminances(C1000 cd m^(-2)) have been obtained, satisfying the demand for indoor lighting. Remarkably, a CRI of 88 is the highest among hybrid WOLEDs. Moreover, the device exhibits low voltages, with a turn-on voltage of only 2.5 V([1 cd m^(-2)), which is the lowest among hybrid WOLEDs. The intrinsic working mechanism of the device has also been explored; in particular, the role of n-type ILs in regulating the distribution of charges and excitons has been unveiled. The findings demonstrate that the introduction of n-type ILs is effective in developing high-performance hybrid WOLEDs.

Lighting Design in Europe： Aligning the Demands for Lower Energy Usage with Better Quality

Lighting design is one of the fastest changing areas in building engineering. It has evolved significantly in recent years due to changing technology and demands for improved quality, better control, reduced energy and sustainability. This paper is an overview of what is happening in Europe and elsewhere and examines the literature to find that latest recommendations in the Code for Lighting issued by the SLL （Society of Light and Lighting） in the UK change previous demands for equal illuminance across a working plane to more specific and demanding criteria. There are recommendations for qualitative metrics and better distribution of light so as to enhance the visual appearance of interiors. European standards are also examined and the LENI （lighting energy numerical indicator） has been found to be a better way of reducing energy than installed load. New LED （light-emitting diode） lamp technology is examined and daylight is discussed in the context of these changing demands. It is found that lighting standards and design are changing for the better but that standards will need to evolve further if they are to ensure good quality lighting.

Light Focusing through Scattering Media by Particle Swarm Optimization

We demonstrate light focusing through scattering media by introducing particle swarm optimization for modulat- ing the phase wavefront. Light refocusing is simulated numerically based on the angular spectrum method and the circular Gaussian distribution model of the scattering media. Experimentally, a spatial light modulator is used to control the phase of incident light, so as to make the scattered light converge to a focus. The influence of divided segments of input light and the effect of the number of iterations on light intensity enhancement are investigated. Simulation results are found to be in good agreement with the theoretical analysis for light refocusing.

Near-infrared lead chalcogenide quantum dots:Synthesis and applications in light emitting diodes

This paper reviews the recent progress in the synthesis of near-infrared(NIR) lead chalcogenide(PbX;PbX = PbS,PbSe, PbTe) quantum dots(QDs) and their applications in NIR QDs based light emitting diodes(NIR-QLEDs). It summarizes the strategies of how to synthesize high efficiency PbX QDs and how to realize high performance Pb X based NIR-QLEDs.

Improved blue quantum dot light-emitting diodes via chlorine passivated ZnO nanoparticle layer

In blue quantum dot light emitting diodes(QLEDs),electron injection is insufficient,which would degrade device efficiency and stability.Herein,we employ chlorine passivated ZnO nanoparticles as electron transport layer to facilitate electron injection into QDs effectively.Moreover,it suppresses exciton quenching at the QD/ZnO interface by blocking charge transfer channel.As a result,the maximum external quantum efficiency of blue QLED was increased from 2.55%to 4.60%,and the operation lifetime of blue QLED was nearly 4 times longer than that of the control device.Our work indicates that election injection plays an important role in blue QLED efficiency and stability.

Efficiency droop suppression in GaN-based light-emitting diodes by chirped multiple quantum well structure at high current injection

Gallium nitride （GaN） based light-emitting diodes （LEDs） with chirped multiple quantum well （MQW） structures have been investigated experimentally and numerically in this paper. Compared to conventional LEDs with uniform quantum wells （QWs）, LEDs with chirped MQW structures have better internal quantum efficiency （IQE） and carrier injection efficiency. The droop ratios of LEDs with chirped MQW structures show a remarkable improvement at 600 mA/mm2, reduced down from 28.6% （conventional uniform LEDs） to 23.7% （chirped MQWs-a） and 18.6% （chirped MQWs-b）, respectively. Meanwhile, the peak IQE increases from 76.9% （uniform LEDs） to 83.7% （chirped MQWs-a） and 88.6% （chirped MQWs-b）. The reservoir effect of chirped MQW structures is the significant reason as it could increase hole injection efficiency and radiative recombination. The leakage current and Auger recombination of chirped MQW structures can also be suppressed. Furthermore, the chirped MQWs-b structure with lower potential barriers can enhance the reservoir effect and obtain further improvement of the carrier injection efficiency and radiative recombination, as well as further suppressing efficiency droop.