脉冲激光远程投送的分布式光纤拉曼温度传感系统

传感光纤分成了前后两段,脉冲激光通过光分路器分成大小不同的两路分别注入前后段传感光纤,后段传感光纤的脉冲激光并不是通过前段传感光纤注入,而是通过一条专用的传输光纤远程投送一段距离后通过波分复用器再注入,该方法能有效提高后段传感光纤的拉曼散射信号强度,从而避免了温度解调精度随传感距离的增大而不断劣化的问题。系统实现了22.7 km的传感距离,前后段传感光纤测温精度±0.5℃。     

多通道光纤光栅压力传感解调系统的设计

针对现有压力监测系统精度较低且成本较高的问题,提出一种基于膜片和悬臂梁技术以及密集波分复用器(DWDM)的多通道光纤光栅压力传感解调系统。考虑到采用多个光电探测器会使系统结构复杂,所以采用光开关来简化。通过光开关分时扫描DWDM的各通道输出光功率,再配合软件进行数据处理,即可获得光纤光栅反射窄带光谱的中心波长与被测压力。实验表明该系统结构简单、成本低、精度较高,在压力范围为0～6MPa时,波长解调分辨率可达0. 3pm,压力测量精度可达0. 15MPa。     

利用三个3×3耦合器串连构成干涉型三波长波分复用器

针对三通道波分复用技术,本文提出了一种利用三个3×3光纤耦合器级联细成的全光纤Mach-Zehnder干涉仪型三波分复用器,运用光纤传输理论和矩阵理论,得到光谱的输出表迭式.通过数值模拟分析了各3×3耦合器耦合比和光纤臂长差对该三波分复用器的影响,并进行了实验.结果表明,当组成的全光纤 Mach-Zehnder干涉仪型三波分复用器的三条光纤干涉臂两两之间分别存在长度差△L和2△L时,在耦合器分光比取一些定值时即可实现三波分复用功能,三端口输出谱线理想,波长间隔仅仅取决于△L的大小,且该器件的输出谱线对耦合器的耦合比不太敏感.实验样品采用的波段为1.55μm,波长复用间隔为0.8 nm,实验所得的结果与理论相吻合.     

用于蓝宝石光纤的光电探测器研究

文章设计了一套比色式蓝宝石光纤气流高温传感器系统,光电探测器作为光转换为电信号的连接元件,具有重要的作用。文章在前期对蓝宝石光纤在不同温度下的光谱辐射特性研究的基础上,进一步研究了适用于蓝宝石光纤的光电探测器,同时根据探测器的不同性能,设计了测试方案,最终根据测试结果确定了适合于蓝宝石光纤高温测量应用的光电探测器。     

基于光纤光栅的波分复用系统设计

设计了两种基于光纤布拉格光栅的波分复用(WDM)系统,一种为基于光纤光栅的四路波分复用系统,另一种为结合光分插复用器(OADM)的四路波分复用系统。给出了基于Opti System的波分复用光传输系统仿真模型,对复用及解复用后的光信号进行仿真得出了光谱图,对传输性能及Q因子、误码率、眼图等参数进行分析。在第二种结构中光纤光栅作为色散补偿器、光反射器和滤波器使用,可以实现任一波长的上载和下路。两种波分复用系统眼图张开良好,误码率均低于10e-9。证明了波分复用系统的正确性和设计方案的可行性。     

高温测量系统研究

介绍一种高温测量系统,其基于Planck辐射原理和光纤测温技术.测量系统由高温光纤传感器、光电探测器、前置放大器和信号处理单元组成.该系统采用标准铂铑30-铂铑6热电偶在卧式炉中实现了标定,该测量系统可以在600℃至1600℃温度范围内使用.     

光纤阵列成像激光雷达系统的设计

简要介绍了光纤阵列成像激光雷达的研究背景、系统优势和发展现状.然后提出了本文设计的雷达系统,并介绍了该系统的工作原理,系统采用光纤阵列前端窗口扫描的方法,避免了光电探测器阵列的制作,同时减少了光电探测器的数量.之后文章对光纤阵列成像激光雷达系统的各部分器件进行分析,包括光纤的选择、光纤阵列的设计和聚焦透镜的分析,并重点讨论了聚焦透镜F值对光纤阵列接收系统的影响,最终得到本系统聚焦透镜F最优值5.47.最后推导了本文光纤阵列成像激光雷达系统的传输效率,给出了传输效率公式.     

基于MEMS闪耀光栅的波分复用器的研究

针对刻划光栅因周期误差和刻线的不平整所带来的鬼线和杂散光的不足和缺陷,提出了基于MEMS闪耀光栅的波分复用器的构成方法,介绍了基于MEMS闪耀光栅的波分复用器的基本组成,介绍了MEMS闪耀光栅的工艺实现以及提高其衍射效率的方案.在LabVIEW中对MEMS闪耀光栅进行了数值仿真分析,同时在ZEMAX中对波分复用器进行了光线追迹,其结果证明了MEMS闪耀光栅应用于波分复用器中的可行性.     

带宽〉40nm的980nmLD泵浦掺Er^3＋光纤放大器模块

在国内首次用９８０ｎｍ激光二极管和参量优化Ｅｒ３＋／Ａｌ３＋共掺杂光纤研制成光学带宽＞４０ｎｍ的光电一体化光纤放大器实用型模块样机。模块净增益２５ｄＢ，饱和输出功率０ｄＢｍ，最大输出功率８ｄＢｍ，噪声系数＜５ｄＢ，可供波分复用光纤通信系统和光孤子传输实验试用。     

宽带光纤拉曼放大器的增益平坦化实验研究

本文采用波长为 1 455nm的大功率光纤拉曼激光器(FRL)作为泵浦源,啁啾布拉格光纤光栅作为增益平坦滤波器,用两种不同的光源组合作为信号源(宽带ASE光源) 波分复用模拟器(WDM-emulator)以及四通道外腔可谐调式激光器(ECL) 滤波器型波分复用器(FWDM))对光纤拉曼放大器的增益平坦化特性进行实验研究,获得了平坦增益带宽为55nm(1 519～1 574nm),平均开关增益大小为15.2dB,增益不平坦度为±0.8dBd的宽带光纤拉曼放大器.通过实验研究表明,该方案为带宽低于60nm的光纤拉曼放大器的增益平坦化设计提供了一种新的选择.     

太阳能微功耗光纤传感式电流互感器

介绍了太阳能微功耗光纤传感式电流互感器的基本原理。该电流互感器具有微功耗的探测部分且以太阳能为其能源，从而实现了光纤传感系统的“无源”化。将其用于高电压系统电流的实时在线监测，不仅保证有较高的测试精度，而且具有可靠工作，调试容易，成本低，安装方便的特点。该系统适应性广，如果更换传感器还可进行其它参量的实时在线监测，从而为光纤传感系统的推广应用开辟了新路。     

Influence of bending on power distribution in step-index plastic optical fibers and the calculation of bending loss

A means of calculating optical power distribution in bent multimode optical fibers is proposed. It employs the power-flow equation approximated by the Fokker-Planck equation that is solved by the explicit finite-difference method. Conceptually important steps of this procedure include (i) dividing the full length of the bent optical fiber into a finite number of short, straight segments; (ii) solving the power equation for each segment sequentially to find its output distribution; and (iii) expressing that output distribution in rotated coordinates of the subsequent segment along the curved fiber to determine the input distribution for that subsequent segment and thus enable the calculation of the power flow and output distribution for it. The segment length and bend-induced perturbation of output angles are determined by geometric optics. The resulting power distributions are given at different cross sections along the curved fiber axis. They vary with the radius of fiber curvature and launch conditions. Results are compared to those for straight fiber. Bending loss is calculated as well.     

Measuring optical fiber length by use of a short-pulse optical fiber ring laser in a self-injection seeding scheme

A method for measuring the length of an optical fiber by use of an optical fiber ring laser pulse source is proposed and demonstrated. The key element of the optical fiber ring laser is a gain-switched Fabry-Perot laser diode operated in a self-injection seeding scheme. This method is especially suitable for measuring a medium or long fiber, and a resolution of 0.1 m is experimentally achieved. The measurement is implemented by accurately determining the pulse frequency that can maximize the output power of the fiber ring laser. The measurement results depend only on the refractive index of the fiber corresponding to this single wavelength, instead of the group index of the fiber, which represents a great advantage over both optical time-domain reflectometry and optical low-coherence reflectometry methods.     

SOA-based multi-wavelength source

A simple fiber laser configuration based on a semiconductor optical amplifier (SOA) is proposed for obtaining multi-wavelength oscillation at room temperature, in which a Sagnac loop mirror is used as the wavelength selective component. The SOA has a flat gain of approximately 23dB within a bandwidth of 12 nm at a small input signal power. The loop mirror was constructed using a 3dB coupler and polarization maintaining fiber (PMF). The output spectrum of the proposed laser can be adjusted by controlling the bias current of the SOA and is quite stable at room temperature. At a bias current of 150 mA, six lines are obtained with at least ?40 dBm output power and 25dB signal-to-noise ratio (SNR). The channel spacing and number of lines is determined by the length of polarization maintaining fiber (PMF) used in the loop mirror. The channel spacing of the proposed laser is 1.49 nm with a PMF 3 m. The multi-wavelength comb output can also be tuned by adjusting the operating temperature of the SOA. The multi-wavelength laser has the advantage of a simple configuration, stability at room temperature, a broad wavelength band, and no need for optical pump lasers.     

太阳能最大功率点跟踪的航模电调设计

根据太阳能光伏输出特性,采用最小二分法实现最大功率点跟踪(MPPT),对于提高太阳能电池的输出功率及太阳能的利用率,特别是在控制电机等感性负载上,意义重大.在航模飞机上,太阳能飞机的飞行受太阳能板输出功率的直接影响,而航模飞机的电调采用中颖公司的SH79F168作为主芯片,太阳能最大功率输出也需要芯片控制太阳能板的输出电压,此设计的目的就是把两者合二为一,以节省空间并提高效能.     

A micro flow cell cytometry based on MEMS technologies using silicon and optical fibers

In this paper, we tested multi-mode optical fibers to select a suitable fiber for effective flow of cell cytometry. In order to align micro nozzle and multi-mode optical fibers, a guide channel was fabricated by silicon wafer etching with MEMS (Micro Electro-Mechanical System) technologies. The fabricated system is advantageous due to its low cost and simplicity in construction. It is possible because multi-mode optical fibers replace many optical lenses and expensive equipment. As a result of the flow cell cytometry using multi-mode optical fibers for both input and output, it is easy to align and we can reduce power consumption. The sensitivity of the micro flow cell cytometry is much better than other cytometries. The output voltage was as high as 300 mV. We injected various cells through the designed and fabricated flow cell cytometry, and we were able to detect cells. Every cell has its own cellulose and wall which cause different light permeability; therefore, we could get different voltage characteristics according to different cells. From the experimental results, we were able to count the number of cells and differentiate the relative size of the injected cells; therefore, we can use the micro flow cell cytometry for analyzing cells [1, 2].     

Fiber-optic temperature sensors based on differential spectral transmittance/reflectivity and multiplexed sensing systems

A concept for optical temperature sensing based on the differential spectral reflectivity/transmittance from a multilayer dielectric edge filter is described and demonstrated. Two wavelengths, λ(1) and λ(2), from the spectrum of a broadband light source are selected so that they are located on the sloped and flat regions of the reflection or transmission spectrum of the filter, respectively. As temperature variations shift the reflection or transmission spectrum of the filter, they change the output power of the light at λ(1), but the output power of the light at λ(2) is insensitive to the shift and therefore to the temperature variation. The temperature information can be extracted from the ratio of the light powers at λ(1) to the light at λ(2). This ratio is immune to changes in the output power of the light source, fiber losses induced by microbending, and hence modal-power distribution fluctuations. The best resolution of 0.2 °C has been obtained over a range of 30-120 °C. Based on such a basic temperature-sensing concept, a wavelength-division-multiplexed, temperature-sensing system is constructed by cascading three sensing-edge filters that have different cutoff wavelengths along a multimode fiber. The signals from the three sensors are resolved by detecting the correspondent outputs at different wavelengths.     

Use of solar cell in electrokinetic remediation of cadmium-contaminated soil

This preliminary study used a solar cell, instead of direct current (DC) power supply, to generate electric field for electrokinetic (EK) remediation of cadmium-contaminated soil. Three EK tests were conducted and compared; one was conducted on a cloudy and rainy day with solar cell, one was conducted on a sunny day with solar cell and another was conducted periodically with DC power supply. It was found that the output potential of solar cell depended on daytime and was influenced by weather conditions; the applied potential in soil was affected by the output potential and weather conditions, and the current achieved by solar cell was comparable with that achieved by DC power supply. Solar cell could be used to drive the electromigration of cadmium in contaminated soil, and removal efficiency achieved by solar cell was comparable with that achieved by DC power supply. Compared with traditional DC power supply, using solar cell as power supply for EK remediation can greatly reduce energy expenditure. This study provided an alternative to improve the EK soil remediation and expanded the use of solar cell in environmental remediation.     

一种新型全光纤弹速测量系统的研制

研制了一种新型的利用激光光束反射原理的全光纤弹速测量系统。该系统采用了全光纤结构和光纤耦合器等无源器件,以输出光功率1mW, 工作波长1300nm的半导体激光器作为测试系统的光源,用光纤耦合器进行分光,实现了在一根光纤中同时传输光源和接受目标反射的信号光,避免了复杂的调节和准直过程。该系统结构简单、可靠性高,利用它,成功地测量了霍普金森杆发射的子弹速度,结果表明其速度测量相对不确定度小于1%。     

太阳模拟器关键参量校准方法研究

提出了一种在线校准太阳模拟器电学参量测量准确度的方法,可以实现伏安特性曲线的多量程校准,利用此方法搭建了太阳模拟器电子负载箱电流、电压、功率等关键电学参量校准装置。针对太阳模拟器辐照不均匀度、不稳定度校准装置,分析了太阳电池探测器温度和负载阻值对太阳模拟器均匀性校准结果的影响,发现对于常规尺寸156mm×156mm单晶太阳电池探测器,负载阻值应小于30mΩ;当辐照不均匀度测试过程中探测器温度保持恒定情况下,恒定温度量值大小对辐照不均匀度测量结果无影响。