Topological slow light and rainbow trapping of surface wave in valley photonic crystal bounded by air

Topological slow light and rainbow trapping tend to rely on large-scale interface structure in previous research work,which have restricted further miniaturization.In this work,we propose a method to realize slow light and rainbow trapping at the zigzag edge of a single valley photonic crystals(VPCs)bounded by air,which is very different from previous studies where rainbow trapping is supported at the interface separating two VPCs with inversion symmetry.By constructing the VPC–air boundaries and VPC–VPC interfaces experimentally,we have observed the topologically protected rainbow trapping simultaneously at the external and internal boundary.This work provides a feasible platform for the miniaturized optical communication devices such as optical buffers,optical storage and optical routing.

Light trapping characteristics of glass substrate with hemisphere pit arrays in thin film Si solar cells

In this paper, the light trapping characteristics of glass substrate with hemisphere pit （HP） arrays in thin film Si solar cells are theoretically studied via a numerical approach. It is found that the HP glass substrate has good antireflection properties. Its surface reflectance can be reduced by - 50% compared with planar glass. The HP arrays can make the unabsorbed light return to the absorbing layer of solar cells, and the ratio of second absorption approximately equals 30%. Thus, the glass substrate with the hemisphere pit arrays （HP glass） can effectively reduce the total reflectivity of a solar celt from 20% to 13%. The lip glass can also prolong the optical path length. The numerical results show that the total optical path length of the thin film Si solar cell covered with the HP glass increases from 2ω to 409. These results are basically consistent with the experimental results.

Scalable fabrication of geometry-tunable self-aligned superlattice photonic crystals for spectrum-programmable light trapping

Superlattice photonic crystals (SPhCs) possess considerablepotentials as building blocks for constructing high-performancedevices because of their great flexibilities in opticalmanipulation. From the prospective of practical applications,scalable fabrication of SPhCs with large-area uniformity and precisegeometrical controllability has been considered as one prerequisitebut still remains a challenge.

Beyond Lambertian light trapping for large-area silicon solar cells:fabrication methods

Light trapping photonic crystal(PhC)patterns on the surface of Si solar cells provides a novel opportunity to approach the theoretical efficiency limit of 32.3%,for light-to-electrical power conversion with a single junction cell.This is beyond the efficiency limit implied by the Lambertian limit of ray trapping~29%.The interference and slow light effects are harnessed for collecting light even at the long wavelengths near the Si band-gap.We compare two different methods for surface patterning,that can be extended to large area surface patterning:1)laser direct write and 2)step-&-repeat 5×reduction projection lithography.Large area throughput limitations of these methods are compared with the established elec-tron beam lithography(EBL)route,which is conventionally utilised but much slower than the presented methods.Spec-tral characterisation of the PhC light trapping is compared for samples fabricated by different methods.Reflectance of Si etched via laser patterned mask was~7%at visible wavelengths and was comparable with Si patterned via EBL made mask.The later pattern showed a stronger absorbance than the Lambertian limit6.

Improving light trapping and conversion efficiency of amorphous silicon solar cell by modified and randomly distributed ZnO nanorods

Three-dimensional （3D） nanostructures in thin film solar cells have attracted significant attention due to their appli- cations in enhancing light trapping. Enhanced light trapping can result in more effective absorption in solar cells, thus leading to higher short-circuit current density and conversion efficiency. We develop randomly distributed and modified ZnO nanorods, which are designed and fabricated by the following processes： the deposition of a ZnO seed layer on sub- strate with sputtering, the wet chemical etching of the seed layer to form isolated islands for nanorod growth, the chemical bath deposition of the ZnO nanorods, and the sputtering deposition of a thin Al-doped ZnO （ZnO：Al） layer to improve the ZnO/Si interface. Solar cells employing the modified ZnO nanorod substrate show a considerable increase in solar energy conversion efficiency.

Dependence of charge trapping of fluorescent and phosphorescent dopants in organic light-emitting diodes on the dye species and current density

This paper utilizes multilayer organic light-emitting diodes with a thin layer of dye molecules to study the mech- anism of charge trapping under different electric regimes. It demonstrates that the carrier trapping was independent of the current density in devices using fluorescent material as the emitting molecule while this process was exactly opposite when phosphorescent material was used. The triplet-triplet annihilation and dissociation of excitons into free charge carriers was considered to contribute to the decrease in phosphorescent emission under high electric fields. Moreover, the fluorescent dye molecule with a lower energy gap and ionized potential than the host emitter was observed to facilitate the carrier trapping mechanism, and it would produce photon emission.

Development of an automatic monitoring system for rice light-trap pests based on machine vision

Monitring pest populations in paddy fields is important to effectively implement integrated pest management.Light traps are widely used to monitor field pests all over the world.Most conventional light traps still involve manual identification of target pests from lots of trapped insects,which is time-consuming,labor-intensive and error-prone,especially in pest peak periods.In this paper,we developed an automatic monitoring system for rice light-trap pests based on machine vision.This system is composed of an itelligent light trap,a computer or mobile phone client platform and a cloud server.The light trap firstly traps,kills and disperses insects,then collects images of trapped insects and sends each image to the cloud server.Five target pests in images are automatically identifed and counted by pest identification models loaded in the server.To avoid light-trap insects piling up,a vibration plate and a moving rotation conveyor belt are adopted to disperse these trapped insects.There was a close correlation(r=0.92)between our automatic and manual identification methods based on the daily pest number of one-year images from one light trap.Field experiments demonstrated the effectiveness and accuracy of our automatic light trap monitoring system.

An Insect Imaging System to Automate Rice Light-Trap Pest Identification

Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and leads to fatigue and an increase in the error rate. A rice light-trap insect imaging system is developed to automate rice pest identification. This system can capture the top and bottom images of each insect by two cameras to obtain more image features. A method is proposed for removing the background by color difference of two images with pests and non-pests. 156 features including color, shape and texture features of each pest are extracted into an support vector machine （SVM） classifier with radial basis kernel function. The seven-fold cross-validation is used to improve the accurate rate of pest identification. Four species of Lepidoptera rice pests are tested and achieved 97.5% average accurate rate.

Comparative Human Landing Catch and CDC Light Trap in Mosquito Sampling in Knowlesi Malaria Endemic Areas in Peninsula Malaysia

Adult mosquito sampling techniques are essential for monitoring transmission of malaria and other mosquito borne infections. Preference for any sampling technique depends on both its field efficiency and the characteristics of local vector populations. Surveys on adult mosquitoes using Human Landing Catch (HLC) and CO2-baited CDC light trap (CDC-LT) techniques were conducted in several knowlesi malaria endemic areas between the months of March to December 2012 in several states of Peninsula Malaysia. These two techniques were relatively compared to determine the preferences of anopheline mosquitoes towards CO2-baited CDC-LT technique using HLC technique as the reference method. Cx. gelidus, An. maculates and An. introlatus were the main three species collected by HLC technique, whereas the species collected by CO2-baited CDC-LT technique were mostly An. cracens, Ar. durhami and Coquillettidia species. Most of the Anopheles species were collected almost exclusively by the human collectors except for An. cracens and An. introlatus which were collected using both techniques. Anopheles cracens was the most dominant species captured using CO2-baited CDC-LT technique. This is the first report showing An. cracens was caught using CO2-baited CDC-LT technique in Malaysia.

基于仿生学的横编保暖面料开发与性能评价

为了研发具有出色热湿性能的针织保暖面料,本文对三类蝴蝶鳞片进行分析,并利用SolidWorks软件建立了几何结构的三维模型。根据模型特征,采用双股13 tex×2羊绒纱线混锦纶热熔丝开发出了三种仿蝴蝶鳞片表面陷光结构针织面料。在此基础上,对仿生结构针织物的保暖性、透湿性和透气性进行了测试,以全面评估其热湿舒适性。其结果表明:以羊绒纱线为原料织造的蝶翅结构仿生织物不仅热湿舒适性能良好,且织造工艺简洁高效,拓宽了从织物组织结构设计方面开发功能纺织品的思路。

基于光捕获效应的Ti3C2Tx/硅纳米线异质结光电探测器

通过金属辅助化学刻蚀法制备了硅纳米线(Si NWs),使用最小强化层脱层刻蚀技术分离了Ti_(3)C_(2)Tx纳米片,随后构筑了Ti_(3)C_(2)Tx/Si NWs异质结光电探测器。利用扫描电子显微镜对Ti_(3)C_(2)Tx/Si NWs的形貌进行分析,采用X射线衍射仪分析了Ti_(3)C_(2)Tx的结构。器件分析表明,该器件呈现出宽带响应特性,在920 nm处具有约526 mA/W的峰值响应度,其响应相较于平面硅器件有了很大的提升。这种光电特性与Si NWs中的光捕获效应有关。这些结果表明,Si NWs是未来高性能硅基光电探测器的潜在构建模块。

Matter-wave interference in an axial triple-well optical dipole trap

This paper proposes a scheme of axial triple-well optical dipole trap by employing a simple optical system composed of a circular cosine grating and a lens. Three optical wells separated averagely by -37 μm were created when illuminating by a YAG laser with power 1 mW. These wells with average trapping depth -0.5 μK and volume -74 μm^3 are suitable to trap and manipulate an atomic Bose-Einstein condensation （BEC）. Due to a controllable grating implemented by a spatial light modulator, an evolution between a triple-well trap and a single-well one is achievable by adjusting the height of potential barrier between adjacent wells. Based on this novel triple-well potentials, the loading and splitting of BEC, as well as the interference between three freely expanding BECs, are also numerically stimulated within the framework of mean-field treatment. By fitting three cosine functions with three Gaussian envelopes to interference fringe, the information of relative phases among three condensates is extracted.

Controllable optical multi-well trap and its optical lattices using compounded cosine patterns

This paper proposes a flexible scheme to form various optical multi-well traps for cold atoms or molecules by using a simple optical system composed of an compounded amplitude cosine-only grating and a single lens illuminated by a plane light wave or a Gaussian beam. Dynamic manipulation and evolution of multi-well trap can be easily implemented by controlling the modulation frequency of the cosine patterns. It also discusses how to expand this multi-well trap to two-dimensional lattices with single- or multi-well trap by using an orthogonally or non-orthogonally modulated grating, as well as using incoherent multi-beam illumination, and these results show that all the symmetric structures of two-dimensional Bravais lattices can be obtained facilely by using proposed scheme.

Intense source of cold cesium atoms based on a two-dimensional magneto–optical trap with independent axial cooling and pushing

We report our studies on an intense source of cold cesium atoms based on a two-dimensional（2D） magneto–optical trap（MOT） with independent axial cooling and pushing.The new-designed source,proposed as 2D-HP MOT,uses hollow laser beams for axial cooling and a thin pushing laser beam to extract a cold atomic beam.With the independent pushing beam,the atomic flux can be substantially optimized.The total atomic flux maximum obtained in the 2D-HP MOT is4.02 × 1010atoms/s,increased by 60 percent compared to the traditional 2D＋MOT in our experiment.Moreover,with the pushing power 10 μW and detuning 0Γ,the 2D-HP MOT can generate a rather intense atomic beam with the concomitant light shift suppressed by a factor of 20.The axial velocity distribution of the cold cesium beams centers at 6.8 m/s with an FMHW of about 2.8 m/s.The dependences of the atomic flux on the pushing power and detuning are studied in detail.The experimental results are in good agreement with the theoretical model.

两种诱虫灯下亚洲玉米螟种群动态及迁飞状态分析

【目的】亚洲玉米螟(Ostrinia furnacalis)是我国玉米生产中最具毁灭性的鳞翅目迁飞害虫之一,严重威胁玉米安全生产,比较和评价地面灯和探照灯诱集的玉米螟种群动态和迁飞状态,为玉米螟精准防控技术制定和迁飞监测预警提供科学依据。【方法】2019—2023年连续5年在山东烟台利用地面灯和高空探照灯对玉米螟进行监测,每年4月1日至10月31日逐日检查并统计两种诱虫灯下的玉米螟数量,通过绘制监测曲线分析玉米螟的种群动态;根据每日诱虫量占全年诱虫量的百分比研究分析玉米螟的上灯规律;根据迁飞性昆虫种群数量“突增突减”现象,以及探照灯和地面灯诱虫数量比值,分析玉米螟的迁飞状态。【结果】玉米螟发生数量在年度间和月份间呈差异变化,且探照灯对玉米螟的诱集量高于地面灯,经Pearson相关分析,两种诱虫灯年诱虫总量之间不存在相关性;地面灯和探照灯监测的玉米螟种群动态基本一致,但探照灯诱虫高峰明显,且开始时间早,结束时间晚;地面灯和探照灯下玉米螟上灯规律一致,只有高峰日、一般发生日和不发生日3种类型,且高峰日均以7月中旬为分界点呈现前后两个高峰阶段;迁飞状态分析显示,玉米螟总体上分为两个迁飞过程,5月下旬至6月下旬为第一个迁飞过程,虫量少、历期短,7月下旬至9月中旬为第二个迁飞过程,虫量多、历期长。【结论】地面灯和探照灯下玉米螟种群动态一致,两种灯均可用于监测玉米螟发生动态,但探照灯诱虫数量多、诱虫高峰明显、第一个高峰日早、高峰历期长,在监测玉米螟早期迁飞状态方面更具优势,可及时监控玉米螟发生情况,并做好防控准备;地面灯和探照灯下玉米螟上灯规律一致,其高峰日均分前后两个高峰阶段,且高峰日状态明显,均可用于监测玉米螟上灯规律;玉米螟5月下旬至6月下旬经烟台从南往北迁飞,7月下旬至9月中旬往南回迁,可提前在玉米螟迁飞路径上加强监测预警,并开展精准防控工作控制玉米螟迁飞种群数量。

Influence of Trap Construction on Mosquito Capture

During 2009 and 2010, 23 night-time mosquito captures were made at Kanci obora in south-eastern Moravia, Czech Republic. It was used in the Centers for Disease Control and Prevention （CDCP） miniature light traps with CO2 （dry ice） and baited lard-can traps in which sentinel animals were replaced with a container filled with CO2 （dry ice）. In the observed period, a total of 31,882 female mosquitoes were captured by CDC miniature light traps with CO2. Lard-can traps baited with CO2 captured 995 females under the same conditions, which is just 3.12% of the quantity from the CDC traps. At the same time, there were significant differences in the proportional captures of various species. Compared to CDC miniature light traps, baited lard-can traps much more often captured Aedes cinereus （16.58% of total versus 1.93% in CDC traps）, Culex modestus （15.48% versus 4.62%）, and Ae. rossicus （6.13% versus 2.67%）. On the other hand, capture of female Ae. vexans was proportionally much lower （15.38% versus 36.41%）. Capture of Cx. pipiens was more or less the same 14.77% （miniature light traps） and 15.76% （baited lard-can traps）. The occurrence of the calamity species Ae. sticticus was proportionally very high in both trap types （30.05% in lard-can traps baited with CO2, 33.58% in CDC miniature light traps）. The findings prove that a trap＇s design itself significantly affects not only the overall capture of mosquitoes but also the proportional representation of individual species.

河南省新乡地区金龟甲发生动态及影响因子分析

为明确河南省新乡地区农田地下害虫优势种群组成、发生动态及影响因子,本研究于2015-2021年间利用虫情测报灯对该地区的金龟甲进行了监测。结果表明铜绿丽金龟Anomala corpulenta Motschulsky和暗黑鳃金龟Holotrichia parallela Motschulsky为河南新乡小麦-玉米/花生1年2熟制农田地下害虫的优势种群,且暗黑鳃金龟的年度诱虫量及其在混合种群中的占比呈逐年增加趋势。金龟甲的发生在不同年份呈现单峰或双峰,暗黑鳃金龟发生盛期表现出明显的隔日出土现象即双倍节律。相较于暗黑鳃金龟发生期的6月中旬至9月上旬,铜绿丽金龟的发生期相对较短,在6月下旬至8月下旬。同时暗黑鳃金龟高峰日也晚于铜绿丽金龟,其中高峰日最多差22 d。金龟甲的发生与环境降雨、湿度、温度相关。本研究为新乡地区乃至黄淮海农田地下害虫的危害预警和综合治理提供数据支撑。

枸杞蛀果蛾趋光特性及其种群动态

枸杞蛀果蛾(Scrobipalpa erichiodes Bidzilya et Li)是枸杞的重要害虫,以幼虫钻蛀枸杞花蕾或果实为害。由于幼虫为害过程和栖息场所隐蔽,仅成虫期暴露,化学防治困难。作者采用便携悬挂式太阳能光控型诱虫试验装置,研究红色、橙色、黄色、绿色、青色、蓝色、紫色7种不同波段LED光源对枸杞蛀果蛾的诱集效果,并利用诱捕效果高的紫色光源灯具监测种群发生动态。结果表明,紫色光源灯具诱捕效果显著好于其他6种光源;与紫色光源波长接近的青色和蓝色也有一定的诱捕效果,但远不及紫色光源。紫色是枸杞蛀果蛾的敏感光源。枸杞蛀果蛾2022年越冬代羽出高峰期在4月下旬,诱虫量高;6月初出现第2个高峰,但虫量较小。

基于红外激光积分球的硅探测器响应非线性研究

0.9μm是我国高温标准光电和辐射法热力学温度测量的主要工作波段之一,因此对该波段下滤光片辐射计的非线性的研究十分重要。基于单相干光源双光路的光通量倍增法设计并搭建了硅探测器光谱响应非线性测量系统,利用双紫外熔融石英分光镜实现光通量的调控,通过积分球使探测器视场被完全充满,提高入射光在探测器光敏面作用区域的重复性,采用高吸收光阱避免光通量调控过程中的多次反射。实验通过切换中性密度滤波片来实现对光电流范围扩展,表征了0.9μm滤光片辐射计在1.6×10-8~8×10-6 A光电流范围内的非线性,单次测量的非线性值为-8.7×10-5~4.8×10-5,单次测量结果标准不确定度优于3.7×10-4,累积测量的非线性值为-2.7×10-4,标准不确定度优于7.6×10-4。

铯基光子学材料研究进展

铯基光子学材料因其稳定的结构、高的发光量子产率和光捕获效率等特性,在发光二极管、激光、光伏电池等光电领域展现出巨大的应用潜力。在盐湖铯元素有效提取的基础上,设计合成高性能铯基光子学材料,进一步开发其高端应用,探索铯元素的高值化利用,发展新型铯基应用材料是盐湖资源综合利用的重要领域。文章主要对铯基荧光和激光材料、非线性光学材料和光捕获材料等研究现状进行了系统梳理、分析和展望,为盐湖铯资源的规模化开发和高值化利用提供有效参考。