Two-dimensional materials-decorated microfiber devices for pulse generation and shaping in fiber lasers

Two-dimensional（2D） materials have been regarded as a promising nonlinear optical medium for fabricating versatile optical and optoelectronic devices. Among the various photonic applications, the employment of 2D materials as nonlinear optical devices such as saturable absorbers for ultrashort pulse generation and shaping in ultrafast lasers is one of the most striking aspects in recent years. In this paper, we review the recent progress of 2D materials based pulse generation and soliton shaping in ultrafast fiber lasers, and particularly in the context of 2D materials-decorated microfiber photonic devices. The fabrication of 2D materials-decorated microfiber photonic devices, high performance mode-locked pulse generation, and the nonlinear soliton dynamics based on pulse shaping method are discussed. Finally, the challenges and the perspective of the 2D materials-based photonic devices as well as their applications are also discussed.

Two-dimensional gel electrophoresis and surface-enhanced laser desorption ionization-time of flight-mass spectrometry for detection of protein expression profiles in the hippocampus following closed brain injury

Gene expression profile changes in brain regions following traumatic brain injury at the gene level cannot sufficiently elucidate gene expression time, expression amount, protein post-translational processing or modification. Therefore, it is necessary to quantitatively analyze the gene expression profile using proteomic techniques. In the present study, we established a rat model of closed brain injury using Marmarou＇s weight-drop device, and investigated hippocampal differential protein expression using two-dimensional gel electrophoresis and surface-enhanced laser desorption ionization-time of flight-mass spectrometry. A total of 364 protein peaks were detected on weak cation exchange-2 protein chips, including 37 differential protein peaks. 345 protein peaks were detected on immobilized metal affinity capture arrays-Cu, including 12 differential protein peaks Further examination of these differential proteins revealed that glucose-regulated protein and proteasome subunit alpha type 3 expression were significantly upregulated post-injury. These results indicate that brain injury can alter protein expression in the hippocampus, and that glucose-regulated protein and proteasome subunit alpha type 3 are closely associated with the occurrence and development of traumatic brain injury.

ANGULAR SPECTRUM PROPERTY OF SPONTANEOUS EMISSION IN A TWO-DIMENSIONAL UNDULATOR FREE-ELECTRON LASER

The angular spectrum of spontaneous emission in a two-dimensional undulator free-electron laser is analyzed theoretically. Numerical calculation shows that the 3-th harmonic spontaneous emission power density can be greatly enhanced by using a two-dimensional undulator, for which l=s, so the harmonic number can be selected by selecting l. Therefore, the higher harmonic operation of a free-electron laser can be realized selectively.

Passively Q-Switched Yb-Doped Fiber Laser Operating at 1.06 μm with Two-Dimensional Silver Nanoplate as Saturable Absorber

A two-dimensional silver nanoplate is prepared with the seed-mediated growth method and is used for achieving pulse fiber laser operation. By controlling the dimension parameters of the silver nanoplate, the surface plasmon resonance absorption peak of the material is successfully adjusted to 1068 nm. Based on the silver nanoplate as a saturable absorber, a passively Q-switched Yb-doped fiber laser operating at 1062 nm is demonstrated. The maximum average output power of 3.49mW is obtained with a minimum pulse width of 1.84#s at a pulse repetition rate of 65.TkHz, and the corresponding pulse energy and peak power are 53.1 nJ and 28.8mW, respectively.

Structured mirror array for two-dimensional collimation of a chromium beam in atom lithography

Direct-write atom lithography,one of the potential nanofabrication techniques,is restricted by some difficulties in producing optical masks for the deposition of complex structures.In order to make further progress,a structured mirror array is developed to transversely collimate the chromium atomic beam in two dimensions.The best collimation is obtained when the laser red detunes by natural line-width of transition 7S3 → 7P40 of the chromium atom.The collimation ratio is 0.45 vertically（in x axis）,and it is 0.55 horizontally（in y axis）.The theoretical model is also simulated,and success of our structured mirror array is achieved.

Digital communication of two-dimensional messages in a chaotic optical system

The digital communication of two-dimensional messages is investigated when two solid state multi-mode chaotic lasers are employed in a master-slave configuration. By introducing the time derivative of intensity difference between the receiver （carrier） and the transmittal （carrier plus signal）, several signals can be encoded into a single pulse. If one signal contains several binary bits, two-dimensional messages in the form of a matrix can be encoded and transmitted on a single pulse. With these improvements in secure communications using chaotic multi-mode lasers, not only the transmission rate can be increased but also the privacy can be enhanced greatly.

近地小行星材料特性对激光烧蚀驱动效率的影响试验分析

基于激光驱动效果和小行星材料特性密切相关的问题,针对脉冲激光对近地小行星物质的烧蚀驱动效率开展了试验研究,选用不同材质、孔隙率的类小行星试验样品,开展了冲量耦合规律测量试验。试验结果表明:在脉冲激光烧蚀的作用下,C型小行星比S型小行星具有更高的冲量耦合效率;随着小行星孔隙率的升高,冲量耦合效率降低,激光烧蚀驱动的效率下降。此外,还对激光烧蚀类小行星物质质量变化的规律进行试验,试验结果表明存在使得小行星质量烧蚀效率最佳的激光功率密度。对于需长期预警时间的威胁小行星,在烧蚀驱动偏转其轨道的同时,以最快的速率减少其质量,可进一步提升防御效率,实现防御的目的。

基于卡尔曼算法的激光告警自适应控制系统

针对二维激光告警系统在极端环境下成像质量差的问题,设计了一种基于卡尔曼算法的自适应控制系统。采用两个InGaAs焦平面阵列探测器分别对来袭激光的角度进行精测和粗测,对卡尔曼算法进行推导优化和仿真验证,同时,基于改进后的卡尔曼算法,通过FPGA实现两个探测器的自适应积分控制,达到系统输出自适应控制的目的。结果显示,精测的卡尔曼预测平均误差为0.56%,粗测的卡尔曼预测平均误差为0.78%,在532 nm的模拟光源照射下,自适应控制系统在极端光强下减少了欠曝和过曝的干扰,在不同光强下光斑大小稳定在55个像素左右。实验表明,自适应控制系统提高了激光告警系统在不同光强下的成像稳定性,对激光告警系统在恶劣环境下工作具有重要意义。

基于FPGA的双目高精度宽波段激光告警系统

针对传统二维激光告警系统的光斑中心提取误差大、角度测量精度差和分辨率低的问题,设计了一种基于FPGA和InGaAs焦平面阵列探测器的高精度宽波段激光告警系统,对传统的Otsu(最大类间方差法)阈值分割算法进行了推导和优化,同时,基于改进后的算法,通过FPGA实现了光斑中心坐标提取以及方位角、俯仰角等参数的计算,并将结果传输至上位机实时监测;实验结果显示,相较于传统的阈值分割算法,改进后的Otsu算法使光斑中心提取精度达到了0.06个像素,改进后的激光告警系统角度测量平均误差为0.03°,角度分辨率达到0.05°;实验表明,双目高精度宽波段激光告警系统达到了实际应用的要求,提高了系统测量的角度分辨率和精度,对光电探测和激光告警领域的工作具有一定的意义。

一种高效舰载激光告警设备检测系统及方法

文章首先介绍了舰载激光告警设备应用情况,及其现阶段进行功能检测与维护的相关技术难点,针对现有装备检测手段机动性差、效率低、可达性不足、功能单一的情况,提出一种基于无人机平台的检测系统及方法,阐述了该检测系统的功能组成、工作原理及关键组件的性能设计方案,并对系统的模拟等效性进行分析,指出该系统的工作特点与性能优势,为告警装备检测提供了一种有效技术手段。

基于激光雷达的汽车起重机近电作业预警技术

为了解决汽车起重机在施工现场中靠近带电线路导致危险情况发生的问题,文中提出了一种基于激光雷达的近电距离预警方法,创新性地采用DBSCAN聚类算法和RANSAC随机抽样一致算法,基于空间直线距离计算方法实时监测并计算起重机吊臂吊钩与施工现场中带电线路之间的距离;通过实时显示预警距离和声音报警,为操作人员提供直观、准确地现场信息,有效提高了起重机作业的安全性,并保障了人员和设备的安全。同时,该方法对推动汽车起重机行业的智能化、精细化发展具有重要意义。

综采工作面刮板输送机窜动机理及主动控制方法

为研究综采工作面刮板输送机窜动机理,综合分析进刀工艺、工作面倾角、支架推力对刮板输送机窜动的影响,理清了刮板输送机的窜动机理,界定了刮板输送机窜动的临界位置与允许窜动量,设置了窜动预警区,明晰了刮板输送机的窜动状态,并提出监测和主动控制窜动的有效方法。研究表明:两端头推进度差、工作面倾角变化、液压支架推力与刮板输送机窜动趋向关系是产生窜动的主要原因;以采煤机恰能完成端部斜切进刀与采煤工作面安全出口最小宽度(0.8 m)为临界,确定了刮板输送机窜动的临界位置;当采煤机在机头恰能完成斜切进刀时,刮板输送机机头位置为机头窜后的临界位置;当桥式转载机挡煤板距煤柱帮的距离为0.8 m时,刮板输送机机头位置为机头窜前的临界位置;当采煤机在机尾恰能完成斜切进刀时,刮板输送机机尾位置为机尾窜前的临界位置;当刮板输送机机尾距煤柱帮的距离为0.8 m时,刮板输送机机尾位置为机尾窜后的临界位置;机头(尾)在窜前临界位置与窜后临界位置之间运动的区间长度即为刮板输送机的允许窜动量;为及时预警、主动控制窜动,将允许窜动量等量划分为窜前严重区、窜前警戒区、正常区、窜后警戒区、窜后严重区5个区域;采用激光定位方法,记录激光定位点与基准标记点的水平错距,精准判定两端头所在窜动区域;根据刮板输送机机头、机尾所在的窜动区域可将窜动状态分为正常状态、单窜状态、双窜状态;针对特定的窜动状态,因地制宜提出调整进刀工艺、工作面伪斜角、支架推力等主动控制窜动的有效措施;相关成果在华阳新材料股份有限公司二矿展开应用,确定了80807工作面机头与机尾的允许窜动量分别为0.8 m与1.0 m,划分了窜动预警区域,利用激光监测精准判定了刮板输送机的窜动状态,并及时采取对应的控窜措施,取得了良好的控制效果。

基于物联网激光测距预警装置在井下机车上的应用

以某煤矿井下机车为研究对象,基于物联网技术从硬件和软件两方面建立激光测距预警装置,并将该系统应用在某煤矿井下机车调度系统中后进行测验,对实际应用效果进行分析。实践表明,该预警装置各项指标都可以满足煤矿安全生产的要求。

2D parameter optimization of Ne-like Cr x-ray laser on slab

A method of studying a non-equilibrium x-ray laser plasma is developed by extending the existing one-dimensional similarity equations to the case of two-dimensional plasma study in the directions perpendicular to the slab and along a focal line. With this method the characteristics of pre-plasma are optimized for transient neon-like Cr x-ray laser. It is found that when the duration and the intensity of 1.053μm pre-pulse are 1.2 ns and 6.5 TW/cm^2 respectively with a delay time of 1.5 ns, the temperature and the temperature discrepancy each approach a proper state, which will provide a uniform distribution of properly ionized neon-like Cr ions before the arrival of pumping pulse.

Radiation effects of electrons on multilayer FePS3studied with laser plasma accelerator

Space radiation with inherently broadband spectral flux poses a huge danger to astronauts and electronics on aircraft,but it is hard to simulate such feature with conventional radiation sources. Using a tabletop laser-plasma accelerator, we can reproduce exponential energy particle beams as similar as possible to these in space radiation. We used such an electron beam to study the electron radiation effects on the surface structure and performance of two-dimensional material(Fe PS3).Energetic electron beam led to bulk sample cleavage and damage between areas of uneven thickness. For the Fe PS3sheet sample, electron radiation transformed it from crystalline state to amorphous state, causing the sample surface to rough.The full widths at the half maximum of characteristic Raman peaks became larger, and the intensities of characteristic Raman peaks became weak or even disappeared dramatically under electron radiation. This trend became more obvious for thinner samples, and this phenomenon was attributed to the cleavage of P–P and P–S bonds, destabilizing the bipyramid structure of [P2S6]4-unit. The results are of great significance for testing the maximum allowable radiation dose for the two-dimensional material, implying that Fe PS3cannot withstand such energetic electron radiation without an essential shield.

宽光谱多参数激光告警探测研究

随着激光技术的发展,激光武器得到了快速发展,针对来袭激光的威胁,激光告警也成为目前各国发展的重点,不同的激光告警系统探测不同的参数,根据告警参数采取相应的躲避和反击措施;目前激光告警主要探测参数有来袭激光方位角、俯仰角、激光波长、激光脉冲宽度等,但现有激光告警系统无法实现多参数的同时探测,且光谱范围窄、视场小、探测俯仰角和方位角为相对角度、无法获得绝对来袭方向。为此本文提出宽光谱波段、大视场、多参数激光告警新方法,可实现450~1700 nm宽光谱来袭激光波长、绝对方位角、绝对俯仰角、脉冲宽度多参数的高精度综合测量,该方法主要由激光脉冲宽度测量、绝对角度及激光波长测量、控制及数据处理三大部分组成。其中脉冲宽度测量模块由光学镜头、多带通窄带滤光片、高速光电探测器组成,实现来袭脉冲激光的高速光电转换;绝对角度及激光波长测量模块由光栅、大视场宽波段消色差镜头、多带通窄带滤光片、宽波段面阵探测器、三维电子罗盘组成,通过一级和零级衍射光斑位置获得来袭激光波长、相对方位角和相对俯仰角信息,结合三维电子罗盘测得的方位角、俯仰角以及横滚角,进而获得来袭激光的三维绝对方位角和绝对俯仰角。多带通窄带滤光片主要是根据常用几个军用激光波长进行选通滤光,有效滤除背景光的影响,降低系统虚警、漏警。理论分析推导具体测量方法和参数,设计宽光谱多参数激光告警探测系统样机,并进行实验可行性验证。实验结果表明,该系统的方位角视场120°、俯仰角视场96°、角度测量精度优于1°、中心波长测量精度优于10 nm、脉宽测量精度优于3 ns。该技术将为海、陆、空、天领域对来袭激光的高精度多参数综合探测奠定基础,有望提高复杂战场的生存能力。

Identification of differentially expressed proteins in human stage Ⅰ lung adenocarcinoma and tumor-adjacent tissues with two-dimension gel electrophoresis profiling

Objective： The aim of this study was to establish reproducible two-dimensional electrophoretic assay used for profiling and identification of differentially expressed proteins in human stage I lung adenocarcinoma and paired normal tumor-adjacent tissue. Methods： The proteins from 12 human stage I lung adenocarcinoma tissues and normal tumor-adjacent tissues were separated using isoelectric focusing electrophoresis （the first dimension） and the subsequent homogeneous SDS-polyacrylamide gel electrophoresis （SDS-PAGE） （the second dimension）. The differentially expressed proteins were determined with PDQuest image analysis software, and identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry （MALDI-TOF-MS） and database searching. Results： The well-reproducible 2-DE gel patterns of human stage I lung adenocarcinoma and normal tumor-adjacent tissues were profiled and 26 differentially expressed proteins uncovered. Nine of these 26 protein spots were cut out from the preparation gels and determined with MALDI-TOF-MS. Searching against the protein database, four candidate proteins were identified. They were 60S acidic ribosomal protein P2, Cathepsin B1, Apolipoprotein A-I precursor, and La 4.1 protein. Conclusion： In this study, high reproducible 2-DE gel protein images of human stage I lung adenocarcinoma and paired normal tumor-adjacent tissues were achieved successfully, and 4 differentially expressed proteins were revealed. These data will be helpful for screen of early biomarker and study of molecular mechanisms of human lung adenocarcinoma.

Passively Q-Switched Erbium-Doped Fiber Laser with TiSe₂as Saturable Absorber

The TiSe2 nanosheets were prepared by means of ultrasound-assisted liquid phase exfoliation (LPE) and the nonlinear saturable absorption properties were experimentally investigated. The modulation depth, saturation intensity and nonsaturable absorbance of the prepared 1T-TiSe2 SA were 15.7%, 1.28 MW/cm2 and 8.2%, respectively. Taking advantage of the saturable absorption properties of TiSe2-based SA, a passively Q-switched erbium-doped fiber (EDF) laser was systematically demonstrated. The pulse repetition rates varied from 24.50 kHz up to 73.79 kHz with the increasing pump power. The obtained shortest pulse width was 1.31 μs with pulse energy of 79.28 nJ. The system presented merits of low-cost SA preparation, system compactness, superb stability and high competition.

宽波段双探测器高精度激光告警采集控制系统

针对二维激光告警中对探测数据高精度、宽波段及大视场角的需要,设计一种基于双探测器结构的高精度数据采集控制系统。提出运用两片GH-VSW640-F15c改进型InGaAs焦平面阵列探测器作为核心器件,重点设计探测器偏置电压电路,模拟信号调理转换传输电路及FPGA控制逻辑。设计电路并进行测试,测试结果显示:在方位角±55°俯仰角±50°的视场范围内,对宽波段0.4μm~1.7μm内不同波长实现双探测器精确高速图像采集,采集时间可达17.3 ms,采集数据角度分辨率为0.05°。实验表明该系统的数据采集精度与实际探测视场范围都达到了实际应用要求,可为二维高精度激光探测与定位系统提供准确的测量数据。

一种多波长多编码合束输出的新型激光源研究

为了模拟复杂条件下的激光威胁源,设计了一种基于多波长多编码合束输出的新型激光产生装置,用于检测相应的激光告警设备。采用3路波长分别为650 nm、808 nm和905 nm的激光,以STC8H单片机为核心构成编码模块,输出调制后的编码激光,通过二向分色镜将3路激光光束合成一束出射,进行了理论分析和实验验证。结果表明,合束的脉冲激光能量最高达到2.45 mJ,光束直径为6 mm,频率调制精度达到0.5 Hz,占空比调制精度达到0.1%;该装置能够实现携带不同编码信息的、不同波长的激光合束出射。该研究为激光告警设备提供了一种新的检测装置,对检测手段的改进有一定的参考意义。