Controllable time delay using slow/fast light in active fiber ring resonators with gain manipulation

We propose to generate controllable time delay using slow/fast light in fiber ring resonators with gain manipulation.The dispersion and group delay of active fiber ring resonator can be controlled by manipulating its gain level below the lasing threshold.Controllability of the negative group delay in the undercoupled regime and the positive group delay in the overcoupled regime is theoretically demonstrated.Besides,large group delay can be obtained accompanied by signal gain in active ring resonators.In addition,we describe wide bandwidth and large group delay in 4-stage cascaded ring resonators.

Majorana fermions induced fast-and slow-light in a hybrid semiconducting nanowire/superconductor device

We investigate theoretically Rabi-like splitting and Fano resonance in absorption spectra of quantum dots(QDs)based on a hybrid QD-semiconducting nanowire/superconductor(SNW/SC)device mediated by Majorana fermions(MFs).Under the condition of pump on-resonance and off-resonance,the absorption spectrum experiences the conversion from Fano resonance to Rabi-like splitting in different parametric regimes.In addition,the Fano resonances are accompanied by the rapid normal phase dispersion,which will indicate the coherent optical propagation.The results indicate that the group velocity index is tunable with controlling the interaction between the QD and MFs,which can reach the conversion between the fast-and slow-light.Fano resonance will be another method to detect MFs and our research may indicate prospective applications in quantum information processing based on the hybrid QD-SNW/SC devices.

Tunable optomechanically induced transparency and fast-slow light in a loop-coupled optomechanical system

We theoretically explore the tunability of optomechanically induced transparency(OMIT)phenomenon and fast-slow light effect in a loop-coupled hybrid optomechanical system in which two optical modes are coupled to a common mechanical mode.In the probe output spectrum,we find that the interference phenomena OMIT caused by the optomechanical interactions and the normal mode splitting(NMS)induced by the strong tunnel coupling between the cavities can be observed.We further observe that the tunnel interaction will affect the distance and the heights of the sideband absorption peaks.The results also show that the switch from absorption to amplification can be realized by tuning the driving strength because of the existence of stability condition.Except from modulating the tunnel interaction,the conversion between slow light and fast light also can be achieved by adjusting the optomechanical interaction in the output field.This study may provide a potential application in the fields of high precision measurement and quantum information processing.

Slow and fast light in quantum-well and quantum-dot semiconductor optical amplifiers Invited Paper

Slow and fast light in quantum-well （QW） and quantum-dot （QD） semiconductor optical amplifiers （SOAs） using nonlinear quantum optical effects are presented. We demonstrate electrical and optical controls of fast light using the coherent population oscillation （CPO） and four wave mixing （FWM） in the gain regime of QW SOAs. We then consider the dependence on the wavelength and modal gain of the pump in QW SOAs. To enhance the tunable photonic delay of a single QW SOA, we explore a serial cascade of multiple amplifiers. A model for the number of QW SOAs in series with variable optical attenuation is developed and matched to the experimental data. We demonstrate the scaling law and the bandwidth control by using the serial cascade of multiple QW SOAs. Experimentally, we achieve a phase change of 160^o and a scaling factor of four at 1 GHz using the cascade of four QW SOAs. Finally, we investigate CPO and FWM slow and fast light of QD SOAs. The experiment shows that the bandwidth of the time delay as a function of the modulation frequency changes in the absorption and gain regimes due to the carrier-lifetime variation. The tunable phase shift in QD SOA is compared between the ground- and first excited-state transitions with different modal gains.

Tunable magnomechanically induced transparency and fast-slow light in a hybrid cavity magnomechanical system

We theoretically explore the tunability of magnomechanically induced transparency(MMIT) phenomenon and fastslow light effect in a hybrid cavity magnomechanical system in which a high-quality yttrium iron garnet(YIG) sphere and an atomic ensemble are placed inside a microwave cavity. In the probe output spectrum, we can observe magnoninduced transparency(MIT) and MMIT due to the photon-magnon and phonon-magnon couplings. We further investigate the effect of atomic ensemble on the absorption spectrum. The results show that better transparency can be obtained by choosing appropriate atomic ensemble parameters. We give an explicit explanation for the mechanism of the Fano resonance phenomenon. Moreover, we discuss phenomena of slow-light propagation. The maximum group delay increases significantly with the increasing atom–cavity coupling strength, and the conversion between slow light and fast light can also be achieved by adjusting the atom–cavity coupling strength. These results may have potential applications for quantum information processing and high precision measurements.

Comparison of Low Stress Mechanical Properties of Light Weight Wool and Wool Blend Fabrics using the KES-F and FAST Instruments

This study compares the test results of the FAST (Fabric Assurance by Simple Testing) with those of the KES - F (Kawabata Evaluation Systems for Fabrics) for a range of nineteen light weight wool and wool blend fabrics in terms of the low - stress mechanical properties of bending, shear, and tensile deformation. It is found that there are very significant correlations between the corresponding parameters for extensibility and shear rigidity obtained from the test results of the two systems. The correlation between the values of bending rigidity obtained from the two systems is only moderate. Furthermore, for the fabrics tested in this study, the values of bending rigidity, shear rigidity, and extensibility measured using the KES - F instruments are higher than those of the corresponding parameters measured using the FAST instruments. The linear regression equation is given for each pair of corresponding parameter.

Multi-window transparency and fast–slow light switching in a quadratically coupled optomechanical system assisted with three-level atoms

We study theoretically the features of the output field of a quadratically coupled optomechanical system assisted with three-level atoms. In this system, the atoms interact with the cavity field and are driven by a classical field, and the cavity is driven by a strong coupling field and a weak signal field. We find that there exists a multi-window transparency phenomenon. The width of the transparent windows can be adjusted by controlling the system parameters, including the number of the atoms, the powers of the lasers driving the atoms and driving the cavity, and the environment temperature. We also find that a tunable switch from fast light to slow light can be realized in this system.

Treading Lightly for Fast Growth

THE Chinese Government announced in early 2012 that the coun- try would continue implementing the proactive fiscal policy and prudent monetary policy to support a steady and relatively fast economic growth. On August 2, the People＇s Bank of China, Chinas central bank, released the Report on the Implementation of Monetary Policies in Q2 2012, showing the policies＇ effectiveness.

一种基于改进FAST的缆芯角度识别算法

成缆机是一种装铠缆线的专用设备,并线工艺是保证成缆品质的关键。本文针对成缆机并线工艺中的缆芯偏转角度识别与纠正的智能化程度低等问题,利用机器视觉技术,分析缆芯截面形状并建立了缆芯光照模型,提出了一种改进的FAST特征识别算法用于缆芯高光特征识别,建立了在缆芯转动状态下的角度计算模型,采用RANSAC算法拟合缆芯高光特征点为直线,从而计算缆芯高光特征点的偏移,将像素坐标下的缆芯高光偏移量转换到世界坐标下,最终实现缆芯角度识别。

纳米纤维素改性染料溶液及其染色单板耐光色牢度性能

采用纳米纤维素晶体(cellulose nanocrystal,CNC)对红、黄、蓝三种酸性染料进行改性处理得到CNC改性染液,对其粒径分散性、Zeta电位、紫外-可见光吸收性能进行分析,并对染色单板的上染率、耐光色牢度、表面化学结构和微观结构进行研究。结果表明:经过CNC改性处理后的三种染料,分散均匀性和稳定性均得到改善。经CNC-1%改性后的染料,粒径降低,粒径分布均匀性和Zeta电位绝对值提高,紫外-可见光吸收强度下降;染色单板的上染率提高,耐光色牢度达到GB/T 15104—2021《装饰单板贴面人造板》4级要求;染色单板微观结构表面具有纳米纤维素与染料复合形成的纤丝状聚集体。较高添加量(CNC-4%)的CNC会增大对染料的吸附量,导致胶体颗粒增大,团聚情况增加,反而使粒径变大,Zeta电位绝对值降低,从而影响单板的上染率和耐光色牢度。

光学参量放大器辅助的复合腔磁系统中磁力诱导透明及快慢光效应

提出了一种含有光学参量放大器的复合腔磁系统。利用系统海森堡-郎之万演化方程和输入-输出关系研究了磁力诱导透明和快慢光效应。数值计算表明:当腔磁系统考虑磁振子-声子耦合时,出现双重透明窗口。磁振子-声子之间的耦合强度增强,透明窗口宽度变宽,深度加深。在系统中调控光学参量放大器的增益,吸收光谱在共振频率两侧出现不对称现象,吸收谱曲线的峰值随光学参量放大器增益的增加而变大。通过调节腔磁耦合强度,改变了吸收光谱和色散光谱的传输特性。此外,探测场的传输速率依赖于光学参量放大器的增益。腔磁系统的快慢光效应及其切换通过调控光学参量放大器得以实现。该研究结果可为量子光学操纵和量子信息存储的研究提供参考。

一种基于FPGA的FTN-VLC系统设计与测试

为了提升可见光通信(VLC)系统的传输速率和频谱利用率,设计了一种基于现场可编程门阵列(FPGA)超奈奎斯特(FTN)-VLC系统。该系统主要由FPGA、数/模(D/A)转换器、低通滤波器、雪崩二极管、电流/电压(I/V)转换器和电压比较器组成。对系统的软件和硬件进行了仿真分析和性能测试。仿真与测试结果表明:当传输距离为0.5 m时,系统的数据传输速率可达10 Mb/s,频谱利用率较同等条件下的奈奎斯特光通信系统提升了18.25%。

旋挤钻法在软土及砂土地层施工灌注桩的研究

研究目的:采用常规旋挖钻法在地下水丰富的黏土地层和软土及砂土地层施工的灌注桩,部分灌注桩因坍孔出现扩径和缩径,扩径浪费混凝土,缩径使灌注桩不合格,由此提出把旋挖钻法改进为旋挤钻法,达到灌注桩轻微扩径不缩径不浪费混凝土的完整合格桩,本文对其展开研究。研究结论:(1)把旋挖钻法钻斗的慢速重钻改进为旋挤钻法钻斗的快速轻钻可行,可减小振动,挤密孔壁土,预防孔壁坍孔;(2)旋挤钻法成孔对于地表浅部极易坍孔地层用长护筒护壁,且护筒长度要大于极易坍孔地层厚度,对于易坍孔和不易坍孔地层用比重1.25和1.15等指标的泥浆护壁,且泥浆护壁是以垂直式的可控泥浆和离心力水平式的扰动土混合泥浆共同作用于护壁,迫使孔内部分扰动土与泥浆粘黏旋挤进入孔壁内,孔壁得到加固稳定不坍孔;(3)采用旋挤钻法在地下水丰富的黏土地层和软土及砂土地层施工的灌注桩,灌注混凝土充盈系数为1.02~1.03和1.04~1.05,均达到轻微扩径不缩径不浪费混凝土的完整合格桩;且成孔效率高,可减少污染、节约成本;(4)本研究成果可为铁路、公路等领域提高混凝土灌注桩施工质量提供参考。

多酚-铁溶液浸渍处理对红锥薄木颜色及耐光色牢度的影响

为丰富红锥(Castanopsis hystrix)薄木的颜色并提高其耐光色牢度,促进红锥人工林木材的增值利用,以单宁酸(tannic acid,TA)、没食子酸(gallic acid,GA)、硫酸亚铁(FeSO_4)和氯化亚铁(FeCl_2)为主要原料,复配5种多酚-铁溶液,对红锥薄木进行常压浸渍处理,获得不同颜色的饰面材料,并采用氙灯老化处理后对其进行耐光色牢度评价。结果表明:利用多酚-铁溶液浸渍处理,获得了以灰蓝、蓝黑色为主的冷色调饰面材料;5种溶液中,染液(FeSO_4+TA+GA)浸渍制备的饰面材料耐光色牢度最佳,等级为3级,光老化前后总色差为4.25,比未处理薄木降低46.34%;多酚-铁体系中Fe^(2+)与Fe^(3+)相互转化,消耗了体系中的自由基,基材中由酚类物质氧化得到的颜色较深的醌类物质减少,从而增强饰面材料的耐光老化性能。

大点数FFT在“申威26010”上的并行优化

根据“神威·太湖之光”超级计算机所用国产“申威26010”处理器的架构特点和编程规范,提出针对大点数FFT的众核并行优化方案.该方案源自经典的Cooley-Tukey FFT算法,通过将一维大点数数据迭代分解为二维小规模矩阵进行并行加速.为了解决矩阵“列FFT”的读写、转置和计算问题,提出“列均分-行连续”的读写策略,通过对数据进行合理的分配、重排、交换,结合SIMD向量化、旋转因子优化、双缓冲、寄存器通信、跨步传输等优化手段,充分利用了众核处理器的计算资源和传输带宽.实验结果显示,单核组64从核并行程序较主核运行FFTW库,可以达到最高65x、平均48x以上的加速比.

纺织品耐光色牢度性能的影响因素分析

耐光色牢度是评价纺织品色牢度的重要指标,耐光色牢度的好坏直接关系着织物的外观,影响消费者的穿着和使用。研究纤维种类、面料颜色深浅和织物结构等对面料耐光色牢度的影响,对纺织品耐光色牢度的提升进行一些有益的探讨。

原液着色涤纶长丝与染色涤纶长丝的性能研究

采用显微镜下纤维形貌特征观察法、拉伸测试、耐光色牢度测试三种方法对原液着色涤纶长丝和染色涤纶长丝进行性能研究,分析二者的不同,为后续深入研究鉴别两类长丝的方法奠定基础。结果表明:染色涤纶纵向表面有明显染料颗粒物析出,形态相对粗糙,部分样品横截面呈现色素分布分层的现象,断裂强度相对较低;原液着色涤纶纵向形态较为光滑,横界面色素分布均匀,断裂伸长率相对较高,且耐光色牢度略高于染色样品,色牢度差值在0.5~1.0级之间。

基于快速以太网的可见光通信系统设计与实现

为了突破当前可见光通信(VLC)设备设计和成本方面的瓶颈,以推动VLC更广泛的普及和应用。提出并实现了一种将快速以太网与VLC相结合的方案,通过直接利用RJ45端口输出的MLT-3信号对可见光进行调制。鉴于LED调制带宽的限制,采用均衡技术拓展发射器的带宽。结果表明,在2 m和0.2 m的传输距离上实现了平均94 Mbps的稳定实时传输。本方案克服了VLC复杂性和高成本的问题,有望推动可见光通信技术在无线通信领域的广泛应用。

实木复合地板耐光色牢度改善初探

分别以柚木和栎木单板为面层,以颜料(色浆类)和染料(色精类)为着色剂,以常规UV涂料和耐黄变UV涂料为涂饰材料制备不同的实木复合地板,对比研究其经10 h、20 h、30 h、40 h和50 h的氙弧光曝晒后耐光色牢度等级的变化情况。研究结果表明,颜料类着色剂对地板样板耐光色牢度等级提升比染料类着色剂要明显;耐黄变UV涂料相较常规UV涂料在一定程度上可提高地板表面耐光老化性能,但效果不明显;在地板样板耐光色牢度等级测试时,曝晒30 h就能很好地反映大部分样板的耐光老化性能。

光、汗作用对棉织物性能的影响

为分析日常生活中光、汗作用对棉织物服用性能的影响,采用4种测试方法对棉织物的耐光、汗色复合牢度进行测试,通过扫描电镜对样品光、汗处理前后的表面形貌进行观察,比较光、汗处理后不同阶段样品的耐摩擦色牢度。结果表明,光、汗作用对棉织物的色牢度和纤维性能有一定的影响,建议企业在生产时应选择适合的光、汗考核标准。