基于无源耦合技术的高速并行光接收模块的设计与实现

提出了一种实现高速并行光接收模块中光电探测器(PD)列阵与光纤列阵精密无源耦合对准的方法,设计并制作了用于这种光学精密对准的所有组件,并用此耦合对准方法完成了PD阵列与光纤阵列之间的光耦合,制作出了12信道并行光接收模块.耦合完成的PD列阵与光纤列阵的对准误差小于1μm,从光纤列阵耦合进入PD列阵的光功率耦合效率大于8...     

光纤耦合效率与接收光强计算研究

由于用近似方法计算出的光纤耦合效率和接收光功率与实验测量之间存在差异,有必要探讨更准确的计算方法以满足应用的需要。通过对径向变量的积分,导出了在高斯光强分布下对接收光纤端面进行面积分计算的一元积分式,从而可以快速准确地对光纤的耦合效率和接收光功率进行数值计算。对62.5/125多模光纤的耦合效率和接收光功率进行的数值计算和实验测量说明,光纤的耦合效率只有用准确的数值计算才能给出与实际相符合的计算结果。使用芯径较大的接收光纤测量出射光束的近场光强分布时,光纤接收光强分布较光束的光强分布有较大的展宽,其相对误差甚至可达60%。     

多倍程激光干涉仪光路几何特性分析

针对纳米计量高分辨力的要求,应用光学倍程法设计了一套基于Michelson激光干涉仪原型的多倍程激光干涉系统.该系统光源由保偏光纤直接导入,采用共光路、立体空间布局设计.通过建立模型分析该干涉系统的几何特性,得出移动镜偏转对该系统带来的影响可以得到有效补偿,因而光路具有很好的稳定性.出射的参考光与测量光始终保持平行,便于干涉系统光路的整体布局与信号接收,同时易于光路的调节从而获得对比度高、信噪比好的干涉信号.     

一种利用EAM实现高效下变频和远程传送光LO信号的ROF结构

提出了一种新颖的光纤无线通信(ROF)系统中高效全光下变频的方案.用此方案可远程传送光本振信号,在无需改变中心站配置和复杂度的情况下,仅需在基站使用一个电吸收调制器就能同时实现对上行链路数据的下变频并进行调制,使得基站不需要光源和本振射频源,大大减小了基站的复杂度,节约了系统成本.通过模拟和实验表明,光本振信号在光纤中传输20km后,对上行链路数据进行相干接收,其功率代价小于4dB.     

基于有源光纤环路的光缓存单元

设计了一个低噪声的EDFA,结合0.8nm的窄带光滤波器,采用长为10439m的标准单模光纤,构成了一个有源光纤环路.对其输出特性进行了详细的测试,测试结果表明该系统具有良好的信号复制能力.基于此设计了一个光缓存单元,描述了其存储原理,定义了其单位缓存时间和最大缓存时间,实验表明该光缓存单元实现了光脉冲信号的缓存,单位缓存时间约为50 μs,复制光脉冲个数在500个以上,相应的最大缓存时间约为25 ms.     

基于红外二级管纠偏探头的设计与验证

通过直流电路驱动红外二级管发出的红外光恒功率发射,红外光经过聚光透镜,形成直径为20mm的光柱.带材正常运动时处于光柱的中心位置,光电二极管接收到的光功率为一定值;当带材偏移时,引起接收管的光功率变化,导致光生电流变化,从而确定偏移量与光生电流的关系.在信号的放大与处理环节采用两级运算放大器相结合的电路,充分减少信号衰减与噪声影响,并产生较大的电压增益,试验表明该电路设计可行并达到一定的精度.     

液体光声效应及光纤水声探测技术的研究

利用液体的光声效应可以实现对液体成分含量的检测.将光纤水声探测技术与液体的声光效应相结合,是一项新的研究内容.本文介绍了液体光声效应产生的三种主要的机制,论述了液体光声效应的研究现状和在科研和生产中的应用.分析了光纤水声传感器用于光声效应中声信号检测的可行性.对各种光纤水听器的结构和原理进行了详细的介绍,对不同类型的光纤水声探测技术进行了讨论和比较,并预测了光纤水听器的发展前景.     

光纤水听器研究进展

1引言 光纤水听器是一种建立在光纤、光电子技术基础上的水下声信号传感器.它通过高灵敏度的光纤相干检测,将水声信号转换成光信号,并通过光纤传至信号处理系统提取声信号信息.光纤水听器主要用于海洋声学环境中的声传播、噪声、混响、海底声学特性、目标声学特性等的监测.它既可用于海洋、陆地石油天然气勘探,也可用于海洋、陆地地震波检测以及海洋环境检测,它又是现代海军反潜作战及水下兵器试验的先进检测手段.     

光纤长度标准和光时域反射计(OTDR)检定装置

中国计量科学研究院最近研究建立并通过鉴定的OTDR标准和装置,采用IEC（国际电工委员会）推荐的标推光纤法。该装置原理先进,方法正确,设计合理。其技术指标达到了当前国际水平（见下表）。光时域反射计（OTDR）能实现单端非破坏性测量,通过将光脉冲单端注入被测量光纤,接收其瑞利后向散射和菲涅尔反射信号,从而得到整个光纤链路的损耗和长度信息。准确测量出光纤的位置／距离、损耗／衰减、故障点和故障点位置。因此它是光通讯领域不可缺少的精密测量仪器。广泛用于光纤和光缆的研究、生产、敷设和维护。随着以光纤为主,微波、…     

浅析光纤连接器对载噪比指标的影响及对策

有线电视不但是由许多电缆接头构成的庞大的“接头”工程,也是由许多光缆接头（连接器）构成的“接头”工程。通常在日常维修中,因光纤连接器不良造成载噪比指标下降的现象屡见不鲜,会导致光节点或光缆网络的接收信号雪花点多,严重时信号无的故障。本文对光纤连接器影响载噪比指标进行初步分析,并提出通过对光纤连接器正确的维护保养来保障光缆网络的可靠性。     

Simple hybrid wire-wireless fiber laser sensor by direct photonic generation of beat signal

Based on direct photonic generation of a beat signal, a simple hybrid wire-wireless fiber laser sensor is proposed. In the sensor, an improved multilongitudinal modes fiber laser cavity is set up by only a fiber Bragg grating, a section of erbium-doped fiber, and a broadband reflector. A photodetector is used to detect the electrical beat signal. Next, the beat signal including the sensor information can access the wireless network through the wireless transmission. At last, a frequency spectrum analyzer is used to demodulate the sensing information. With this method, the long-distance real-time monitor of the fiber sensor can be realized. The proposed technique offers a simple and cheap way for sensing information of the fiber sensor to access the wireless sensor network. An experiment was implemented to measure the strain and the corresponding root mean square deviation is about -5.7 με at 916 MHz and -3.8 με at 1713 MHz after wireless transmission.     

Simultaneous sensing of the strain and points of failure in composite beams with an embedded fiber optic Michelson sensor

A fiber optic Michelson sensor was embedded in composite beams to sense the internal strain and points of failure of the composite structures. The bending deformation and matrix cracking were investigated by four-point bending tests of cross-ply composite beams with the embedded fiber optic sensor. The failure points of composite beams were detected by using both a PZT sensor and a fiber optic sensor in order to investigate the fiber optic failure signals. The failure due to matrix cracks in a composite beam was confirmed by the edge replica method. The digital processing of the fiber optic signal was carried out to determine the strains and failure points of composite beams. The failure points were observed from the processed failure signal by high-pass filtering. The initial failure strain of the composite beam was measured and processed from the fiber optic strain signal after low-pass filtering.     

Sensitive acoustic vibration sensor using single-mode fiber tapers

Optical fiber sensors are a good alternative to piezoelectric devices in electromagnetic sensitive environments. In this study, we reported a fiber acoustic sensor based on single-mode fiber (SMF) tapers. The fiber taper is used as the sensing arm in a Mach-Zehnder interferometer. Benefiting from their micrometer dimensions, fiber tapers have shown higher sensitivities to the acoustic vibrations than SMFs. Under the same conditions, the thinnest fiber taper in this report, with a diameter of 1.7 μm, shows a 20 dB improvement in the signal to noise ratio as compared to that of an SMF. This acoustic vibration sensor can detect the acoustic waves over the frequencies of 30 Hz-40 kHz, which is limited by the acoustic wave generator in experiments. We also discussed the phase changes of fiber tapers with different diameters under acoustic vibrations.     

硅微声光传感特性的实验研究

硅微声光传感器是一种由硅微列阵簧片和光纤组合成的新型传感器，这种传感器在完成声光转换的同时对声频信号进行了并行滤波处理，可用作神经网络的并行输入，是一种光机电一体化的传感系统。本文中叙述通过纤反射强度调制技术检测硅簧片振动信号的方法；通过实验研究，完成了对声光调制信号的探测和预处理，并给出了实测数据及其分析。为实现音频编码和振动信号的实时分析，本文中还给出了采用人工神经网络对阵列传感器的输出信号进     

A Fiber Optic Ultrasonic System to Monitor the Cure of Epoxy

A fiber optic ultrasonic system is described which monitors the cure of an epoxy resin. Ultrasound is generated using a high-power optical fiber to deliver high-energy pulses of light to the prepared surface of an aluminum mold that contains the curing epoxy resin. The generated ultrasound is detected using a local fiber optic ultrasound sensor embedded in the curing epoxy resin. The system was used to measure the ultrasonic signal velocity and ultrasonic attenuation throughout the cure of a neat epoxy resin at room temperature. Similar measurements also were performed using a piezoelectric transducer for ultrasound generation and an embedded fiber optic sensor for detection, which provided verification of the results using the complete fiber optic system. The complete fiber optic system demonstrated adequate sensitivity throughout the entire cure to measure the ultrasonic signal velocity and ultrasonic attenuation.     

Development of optoelectronic-based pulsed current sensor to detect the poor laser discharge condition

A current transformer (CT)-based sensor has been developed to detect poor discharge conditions in copper vapour laser. The optoelectronic-based pulsed current sensor architecture involves the optical transmitter–receiver HFBR, high-frequency current transformer, and fiber optic link. The CT has been designed and calibrated to ensure generation of an optical signal at the current threshold crossover. Bandwidth analysis of the CT is carried out using the bode plot. The optoelectronic inter-conversion of the pulsed voltage of the CT and transmission via fiber optic link provides the non-contact current sensing and remote signal processing of the signal. This study discusses the details of the sensor.     

用于FRP固化在线监测的光纤微弯压力传感器

无论在军事还是航空航天领域,光纤传感器都是一种极具应用前景的智能化监测手段。目前,将光纤传感器用于纤维增强树脂基复合材料固化过程的监测的研究是一个热点。但由于大多数光纤传感器监测固化过程成本较高,所以还没有被广泛的应用于实际生产当中。开发了一种新型的低成本、高灵敏度、易操作的光纤传感器用于纤维增强树脂基复合材料固化过程的在线监测。光纤传感器的设计基于光纤微弯损耗原理,其监测的直接目标参量为增强纤维所构成的网络所承担的压力变化,可以进而通过Gutowski的树脂流动/纤维变形理论间接得出对于固化过程中的几个关键参量。给出了这种压力传感器的设计制作方法,测定该种传感器在静态和动态下的压力-光损耗响应曲线,分析了该传感器对环境温度与折射率变化的响应。完成了利用微弯压力传感器进行纤维增强复合材料在热压釜中固化成型过程的在线监测实验,获得了良好的结果。     

Dual Michelson interferometers for distributed vibration detection

A distributed fiber optic vibration sensor is described, in which two Michelson interferometers are used as phase detectors and two 3×3 couplers are deployed to demodulate the time-varying phase change caused by vibration. The two interferometers are separated by four wavelength division multiplexers. The position of the vibration is obtained by signal correlation, which can be used as a perimeter security sensor to locate the intruder. The experimental results with a 4012?m fiber sensor are discussed.     

Optische Schnittstellen

Optical interfaces: Viewing into the vacuum The requirements concerning in‐vacuum process diagnostics are more and more challenging. On the one hand, the setup itself has to be decoupled from the process to avoid any external impact on the process. On the other hand, the process parameters have to be in‐situ characterized and controlled by an in‐vacuum monitoring system. In the vicinity of these two contradictive requirements optical fiber applications gain more and more impact, since optical fibers cover several advantages: high transmission signal, inherent immunity against external electromagnetic forces, high durability and high mechanical as well as optical flexibility. The focus of the contribution is a new in‐vacuum optical temperature sensor combined with high‐temperature fiber optical feedthroughs. The sensor based on fiber Bragg gratings (FBG) in the optical fiber, which are extremely sensitive to temperature variations. In a first case study, the application of FBG with the feedthrough as an in‐vacuum optical temperature sensor is demonstrated. Thus an optical fiber containing a bunch of several FBG becomes a compact, robust, and flexible in‐vacuum network of local temperature sensors. Each individual sensor captures temperature variations over a signal path that is several km long with a remarkable accuracy up to 0.1 K and with speed of light.     

Femtosecond laser-inscribed fiber Bragg gratings for strain monitoring in power cables of offshore wind turbines

A fiber Bragg grating sensor system used for monitoring the effects of strain on the power cable of an offshore wind turbine is presented. The Bragg grating structure was inscribed into coated nonphotosensitive standard telecommunication fibers using an IR femtosecond laser and the point-by-point writing technique. Because of the presence of the protective coating of the fiber, the mechanical stability of the resultant sensor device is better than that of a sensor consisting of a bare fiber. A system containing this sensing element was to our knowledge for the first time successfully installed and tested in an offshore wind turbine prototype (REpower 6M, REpower Systems, AG, Germany) in February 2010, near Ellh?ft (Germany). The fabrication process of the fiber Bragg gratings, measurement results of the online monitoring, and a comparison between the sensor signal and commonly used sensing techniques are presented.