Novel fiber sensor arrays using erbium-doped fiber amplifiers

We examine the signal-to-noise ratio (SNR) performance of a novel type of time domain multiplexed sensor arrays in which low gain (1-10 dB) fiber amplifiers are incorporated to compensate for splitting losses between sensors. The system noise figure for passive and amplified sensor arrays is presented, along with expressions to optimize the array parameters for high SNRs. We show that practical amplified sensor arrays exhibit low system noise figures that allow much larger arrays (hundreds of sensors) than passive arrays     

提高强度调制型光纤传感器动态探测范围的方法

研究了扩大强度调制光纤传感器动态探测范围的方法 ,通过采用自扫描光电二极管阵列(SSPA)曝光时间控制、激光源输出功率控制和可编程信号调理等措施 ,有效地增强了光电传感器的光信息探测能力     

一种采用Ge/P光纤的强度调制型温度传感器

提出一种基于稳定的光纤辐射致衰减 (RIA)温度依赖性的新型光纤温度传感器。用辐照并充分退火后的光纤制作传感头,搭建光 纤温度传感系统进行测试。建立温度和光纤RIA的模型,并对光纤温 度传感器的灵敏度、线性度和重复性进行分析。结果发现,在－40～ 60℃温度范围内,辐照并充分退火后的Ge/P 掺杂光纤在850nm波段的RIA具有单调 稳定的温度依赖性。通过比较850nm和1310nm波段的RIA温度特性发现,光纤RIA的温度特性具 有波长依赖性,且850nm波段的温度灵敏度要远远优 于1310nm波段。验证了基于850nm波段的光纤RIA温度依赖性的光纤温度传感器的可行性。用18m辐照并充分退火后的Ge/P光纤搭建的光纤温度传感 器,其灵敏度为0.006dB/℃,最大绝对误差 为1℃,分辨率为0.15℃,线性误差为±3.04%,重复性误差为1.04%。     

双倍布里渊频移的多波长掺铒光纤温度传感器

为了实现高灵敏度的光纤温度传感,提出并验证了一种具有双倍布里渊频移间隔的多波长掺铒光纤温度传感器.实验采用1558.214 nm波长的激光输出作为布里渊泵浦,经掺铒光纤放大器放大后再通过由2个三端口环形器和1段20 km的单模光纤构成的双倍频布里渊增益腔,其中单模光纤既是布里渊增益介质又是温度传感元.实验结果表明:在产...     

Temperature-dependent fluorescence characteristics of an ytterbium-sensitized erbium-doped silica fiber for sensor applications

The characteristics of temperature-dependent fluorescence of an ytterbium (Yb³⁺)-sensitized erbium (Er³⁺)-doped silica fiber are presented. A 10-cm long double-clad Yb³⁺/Er³⁺-codoped fiber is diode-pumped at 915 nm and the individual fluorescence intensities from Yb³⁺ and Er³⁺ ions are measured with varying the fiber temperature. The ratio of the dual fluorescence intensities varies exponentially with temperature in the range of room temperature to ∼300 °C. This dual-dopant system has dual emission bands that emit comparable fluorescence powers. Particularly, the self-referencing fluorescence intensity ratio is insensitive to external perturbations in the fiber, which is useful for sensors that are used in a harsh environment without any use of additional referencing techniques. This scheme allows a compact, long-life, and low-cost temperature sensor and can also be combined with a wide range of existing fiber-optic multiplexing schemes that can simultaneously detect multiple physical parameters.     

All silica S-band double-pass erbium-doped fiber amplifier

Double-pass (DP) and single-pass (SP) erbium-doped depressed cladding fiber amplifiers designed for S-band operation are evaluated under changes of the input optical power, pumping power, and fiber bending radius. The DP configuration employs the usual combination of a circulator and a Faraday rotator mirror while the SP is based on the copropagating scheme. The amplifiers were characterized in terms of gain and noise figure. It is demonstrated that the DP topology shows much improved gain performance compared to the SP configuration although the noise figure is slightly degraded by counterpropagating amplified spontaneous emission.     

The long range distributed fiber raman photon temperatree sensor

A 31 km long range distributed optical fiber Raman photon temperature sensor （DOFRPTS） system have been developed based on temperature effect of the amplified spontaneous Raman scattering in fiber, and using fiber laser as a pumped some. The results show that temperature measuring uncertainty is±2 ℃, temperature resolution is 0.1℃, measurement time is 432 s, spatial resolution is less than 4 m.     

The long range distributed fiber raman photon temperature sensor

A 31 km long range distributed optical fiber Raman photon temperature sensor (DOFRPTS) system have been developed based on temperature effect of the amplified spontaneous Raman scattering in fiber, and using fiber laser as a pumped source. The results show that temperature measuring uncertainty is ±2 ℃, temperature resolution is 0.1 ℃, measurement time is 432 s, spatial resolution is less than 4 m.     

High gain limiting erbium-doped fibre amplifier with over 30 dB dynamic range

A limiting optical amplifier is demonstrated using three cascaded stages of erbium-doped fibre amplifiers. A constant output power of +12.9 dBm was obtained for an input power ranging from -30 to 1.5 dBm. The optical noise figure of the amplifier has been measured over the >30 dB dynamic range. Design guidelines for optical limiting amplifiers are also presented.<>     

新型超远程分布式光纤拉曼温度传感器

基于光中继传感技术提出一种超远程分布式光纤拉曼温度传感器方案,采用在分布式光纤传感器的多段传感光缆之间嵌入多级光中继放大传感装置的方式,利用中继放大传感装置的增益克服光纤损耗,增强了光纤中自发拉曼散射光的强度,传感光缆分段分时进行测量.当在多段传感光缆之间引入N个远程光中继放大传感装置进行级联时,可实现分布式光纤传感器...     

利用波长检测的光纤温度传感器

基于应力型保偏光纤传输差对温度的敏感性及保偏光纤模式干涉理论,提出了利用波长的温度检测方法并推导出传感方程.传感方程表现出的温度与干涉频谱中对应的空间频率间呈线性关系,简化了温度解算的程序.实验中,对Fabry-Perot(F-P)可调谐滤波器的工作电压与相对应的允许通过波长的关系进行了研究,并使用F-P可调谐滤波器取代光谱仪来获取光谱,简化了实验设备.由于被测信息仅与波长信息有关,而与光在传播过程中所引起的光源光功率的浮动无关,所以,使用这种检测方法消除了光源的浮动以及光在传榆过程中的损耗等对系统的稳定性和精度的不利影响,提高了传感器的环境适应能力.     

High-resolution neural temperature sensor using fiber Bragggratings

We demonstrate a novel high-resolution neural temperature sensor using two fiber Bragg gratings (FBG's) and a modular artificial neural network which is used to learn the mapping relation among frequency, temperature, and the normalized transmission power spectrum. Because of the fast computational ability of the modular artificial neural network and the sensitivity of FBG's, the sensor can make high-resolution temperature and frequency measurements in real time. The experimental results show that the temperature resolution of this sensor can reach 0.005°C     

大量程分布式光纤传感器的研究与应用

采用线型和螺旋型光纤传感技术相结合的方法研制出大量程、高定位精度的分布式光纤位移传感器,并对其量程扩展技术和埋设工艺进行了探讨。研究表明,研制的分布式光纤传感器水平位移监测的动态范围达到17 mm,深度定位精度为±0.2 m,可根据需求进行量程扩展,非常适合用于滑坡体深部变形的安全监测。     

High pumping-efficiency L-band erbium-doped fiber ASE source using double-pass bidirectional-pumping configuration

We present a high pumping-efficiency L-band (1565/spl sim/1605 nm) erbium-doped fiber amplified spontaneous-emission (ASE) source using a double-pass bidirectional pumping configuration. Such design gives rise to relaxing the danger in resonant lasing, allowing high pumping-power operation, and therefore, enhancing the pumping-conversion efficiency. The ASE source has a mean wavelength of 1584.3 nm, a spectral linewidth of 41.6 nm, and an output power of 71.8 mW with a ripple of 0.5 dB without using any external spectral filters. The high pumping efficiency of 42.2% is achieved.     

Distributed temperature sensing with erbium-doped fiber amplifiers

The experimental verification of a novel fiber-optic sensor which performs distributed measurement of temperature by using a distributed erbium-doped fiber amplifier (EDFA) is presented. The sensor configuration is similar to that of a conventional optical time-domain reflectometer and detects the Rayleigh backscattered portion of a pulsed optical signal which is amplified by the EDFA, along with the backward amplified spontaneous emission (ASE) generated by the EDFA. The sensor utilizes the temperature dependence of the gain in an EDFA. The amplification provided by the erbium-doped fiber, which is pumped at 1.48 μm, significantly increases the magnitude of the optical signal reaching the receiver, thus leading to a simplified configuration and a potentially superior performance as compared to other types of distributed fiber-optic temperature sensors     

High dynamic range image reconstruction for multi-bit quanta image sensor

An adaptive thresholds algorithm is proposed in this letter, which is used to determine the global optimal thresholds for multi-bit quanta image sensor(MB-QIS). Firstly, the senor model of MB-QIS is set up. Then global optimal thresholds theory is analyzed and a thresholds optimization algorithm based on the binary search is designed to determine the optimal global thresholds. Finally, the high dynamic range(HDR) images are reconstructed by the noniterative maximum likelihood estimation(MLE) ima...     

提高强度调制光纤位移传感器测量范围的综合方法探讨

分析提高强度调制光纤位移传感器测量范围的基本方法,研究将各种提高测量范围的基本方法集成的综合方法,构造出该系统的框架结构模型,研究宽测量范围的综合评判规则,达到宽测量范围的效果.充分利用各种方法的优点,实现优化组合,将能较好地满足不同场合.     

Characteristics of erbium-doped superfluorescent fiber sources forinterferometric sensor applications

The characteristics of 1.55 μm Er-doped superfluorescent fiber sources (SFS's), intended for fiber-optic gyroscope (FOG) applications, are explored theoretically and experimentally. With proper selection of the source configuration, fiber length, pump wavelength, pump power, and fiber composition, we show that it is possible to meet the stringent requirements of the FOG, including a high output power, broad emission bandwidth, and excellent spectral thermal stability. Variations of the mean wavelength, spectral width, and output power of the SFS with fiber length, pump power, pump wavelength, and temperature are modeled for representative sources pumped near 980 nm or 1.48 μm, and are shown to be in good agreement with experimental results. The effects of a multimoded pump, erbium ion pair, and optical feedback are also assessed. This study indicates that the Er-doped SFS is an excellent candidate for the FOG and for other applications requiring spatial coherence and low temporal coherence     

基于波长与强度双解调的光纤温度传感器

为了更好的了解光纤传感原理,并提高温度光纤传感器的各方面性能,提出一种新型的具有波长与强度双解调的光纤温度传感器。将30mm的保偏光纤(PMF)的两端分别与单模光纤(SMF)进行腰椎放大熔接,形成两个腰椎,构成全光纤马赫泽德尔(M-Z)温度传感器。温度的变化将会引起光纤的纤芯模与包层模相位差的变化,从而导致干涉光谱的变化。以25-70℃作为测试温度,通过光谱仪(OSA)监测宽带光源经传感器后的干涉光谱。实验结果表明,温度升高,特征峰波长在向长波长方向移动,并且其强度在逐渐增大。因此,采用波长与强度双解调的方法对温度进行测量,其灵敏度分别为0.127nm/℃和0.32dB/℃,对应的分辨率分别为0.16℃和0.03℃。这个双解调的全光纤温度传感器制造简单、成本低、体积小和结构稳固,而且具有很高的分辨率,因此适用于实际测量。     

DMD结合图像传感器的高动态场景成像探测

微镜阵列DMD空间光调制器结合图像传感器能够解决高动态场景中强弱目标同时探测的问题,获得高动态图像数据,能使光电成像设备动态范围扩展到130 dB以上。为了实现快速的像素级光强控制以及获得高质量的实际场景高动态图像数据,根据实际场景成像其非边缘区域的相邻像素值变化缓慢的特点,提出了一种适合DMD驱动方式的像素级调光算法-自适应空间区域法,它具有较快的收敛速度,最坏的情况下,经过N/I次即可完成调光权值的搜索;在以FPGA为驱动核心的高动态场景成像探测实验系统平台上,对DMD的驱动时序进行了分析研究。并通过此实验平台验证了自适应空间区域法的有效性,该方法能够实现对高动态场景中强弱目标的同时探测,具有很好的光强控制质量,对场景光强局部变化的适应性较强。