一种具有迈克耳逊结构的新型光时域反射仪

利用传输光纤中后向瑞利散射光携带有光纤位置、外界振动等信息的特点,采用光纤迈克耳逊结构构成干涉型光时域反射仪,有望以分布方式传感沿光纤的微小振动信号.文中设计了一种新型结构的分布式光纤振动传感器,该传感器用3dB耦合器将波长为1310nm的红外激光分为两路相干光:参考光和传感光,它们中的后向瑞利散射光在耦合器处发生干涉,干涉信号的变化点对应于振动点所在的位置.将没有振动信号、加微小振动信号和加损耗干扰三种情况分别作用于传感光纤并进行了试验对比.结果表明,在微小振动的情况下,光强变化微弱;加损耗时,光强变化显著,定位准确.     

基于熔融拉锥过耦合器的光纤光栅解调系统

提出了一种基于光纤熔融拉锥过耦合器进行解调的方法,实验制作了一个特殊的熔融拉锥过耦合器,对其输出的两路光功率进行了测试,并论证了用该耦合器进行解调的原理.利用该过耦合器组成的检测系统对光纤光栅传感器进行解调,得到了较好的响应.该解调方法成本低,结构简单,解调范围大,线性范围可达10 nm以上.     

单频分布布拉格反射光纤激光器及温度传感实验研究

报道利用Er∶Yb双掺杂光纤制作的单频窄线宽分布布拉格反射 (DBR)光纤激光器。在 980nm半导体激光器抽运下 ,当抽运功率为 75mW时 ,获得了输出功率为 2 3mW的单频激光 ,其中心波长为 1 5 5 7 5 2 4nm ,线宽小于 5MHz。利用制作的单频DBR光纤激光器构成光纤有源传感系统 ,进行温度传感实验研究 ,实验结果线性度很好 ,高信噪比和高输出功率使得该系统具有波长易于检测的优点     

CO2激光熔融毛细管端面制备的光纤F-P压力传感器

提出了一种利用CO2激光熔融毛细管端面来制备光纤法布里-珀罗(F-P)压力传感器的方法。F-P结构由普通单模光纤和基于CO2激光熔融毛细管端面制备的硅薄膜组成。文章详细说明了硅薄膜的制造工艺和熔融参数,并对光纤F-P压力传感器进行了性能测试。实验结果表明:制备的光纤F-P压力传感器对气压具有良好的灵敏度和线性度,灵敏度可达到16.37pm/kPa,线性度为0.998。该光纤F-P压力传感器结构紧凑,易于生产,具有在极端恶劣环境下的应用潜力。     

高分辨率光纤激光传感系统

提出并实现了一种基于光纤光栅(FBG)激光器的高分辨率光纤传感系统。通过在一段高增益有源光纤写入光纤光栅形成光纤激光传感器,待测信号作用在激光器上引起激光频率变化,采用偏振无关的非平衡迈克耳孙光纤干涉仪将激光频率变化转化为干涉仪相位变化。干涉仪输出的信号经过光电转换后,用采集卡转换为数字信号输入计算机,最后利用改进的归一化相位载波(PGC)解调技术,实现信号的高分辨率解调。实验表明该传感系统的动态应变分辨率达到了5.6×10-4nε/Hz,并且解调结果与待测信号具有良好的线性关系。     

熔锥型光纤侧面泵浦耦合器的研究

该文采用泵浦光纤预拉方法得到一款泵浦耦合效率82%,信号光通过率98%,信号输入与泵浦输入隔离度33 dB,泵浦光反向隔离度24 dB的高效熔锥型侧面泵浦耦合器。将该耦合器应用于自制的20 W脉冲激光器,实现了峰值功率为7 kW的稳定激光输出。研究结果表明,所研制的熔锥型光纤侧面泵浦耦合器在高功率光纤激光器和光纤放大器中具有很好的应用前景。     

Star couplers with gain using multiple erbium-doped fibers pumped with a single laser

An economical method for combining erbium-doped fiber (EDF) amplifiers and star couplers, is presented. It involves simultaneously pumping EDFs placed at the input or output ports of the coupler with a single laser pump source distributed through the coupler itself. In this way, many amplifiers can share the cost of a single pump laser, and the need for individual pump/signal combiners is eliminated.<>     

基于光纤光栅的杆型二维振动传感器

为了实现两个方向的振动信号检测,提出了一种以杆为弹性结构的二维光纤光栅振动传感器。首先对该传感器进行了理论分析,并推导出其固有频率和灵敏度公式。然后对传感器结构进行了优化仿真,确定各个参数的最终值。最后通过实验研究了传感器的各项性能。实验结果表明,该传感器在x方向上的固有频率为493 Hz,灵敏度为54 pm/g,线性度为99.9%;在y方向上的固有频率为466 Hz,灵敏度为5 pm/g,线性度为97.5%。此外,采用双光纤光栅消除了温度对振动信号测量的影响,温度灵敏度为0.1 pm/°C。该传感器结构简单,可检测两个方向的振动信号,消除了温度的影响,在振动信号检测中表现良好,因此在多维振动信号检测领域具有重要研究意义。     

利用双激光光源监测甲烷浓度的光吸收法光纤传感器

基于Lamber -Beer定律 ,利用波长为 1.3 3 μm的脉冲lnP/InGaAsP半导体激光器作为测量光源 ,用低损耗的光纤进行光信号的传输并以钽酸锂热释电探测器作光电转换器件 ,设计出了一种新颍的远距离监测甲烷浓度的光纤传感系统。以此光纤传感系统为探头 ,设计出了一种可实时监测甲烷浓度的仪器 ,并能实现 3km的远距离遥测。介绍了该光纤传感系统及由该光纤传感系统构成的监测仪器的基本结构与工作原理 ,讨论了其中的技术难点及其相应的解决方法 ,并给出了监测仪器相应的技术指标     

Diplexer With Integrated Filters and Photodetector in Ge–Si Using $Gamma-{X}$ and $Gamma-{M}$ Directions in a Grating Coupler

We demonstrate a central-office-type diplexer in which the filter and photodetector are monolithically integrated on a silicon-on-insulator substrate. The photonic integrated circuit receives a 1577-nm signal from an external laser and sends it to the fiber link using a two-dimensional grating coupler. The same grating coupler receives a 1270-nm signal from the fiber link and sends it to a monolithically integrated germanium photodetector using a polarization-diversity scheme to achieve polarization independence. The grating coupler is novel in that both the $Gamma-{X}$ and $Gamma-{M}$ directions are employed. This allows the grating coupler to couple both the 1577- and 1270-nm wavelengths with a small fiber tilt angle and hence have low polarization-dependent loss.      

All-optical remote switching for multiplexed optical fiber sensorsand communications systems

All-optical self-routing switches are described which automatically route optical data signals. These switches require no separate source of power, and have been demonstrated to operate from a single input laser beam of 300 μW. The input laser beam contains the data, destination address, and optical power. These optical switches can be used for all-optical communication systems, and are used as an example in this paper to demonstrate remote switching via an optical fiber to a sensor. The sensor modulates the optical carrier which returns the modulated carrier to the source end of the fiber. The switch demonstrates auto-aligning properties which ensure correct rerouting of the modulated signal back to the source. Operation has been demonstrated for all the visible lines of an argon ion laser     

DBR光纤激光器拍频传感及其组网技术研究

研究了基于单纵模分布Bragg反射(DBR)光纤激光器的拍频解调传感技术,并对其组网技术进行了探讨。由于光纤本身的固有双折射,DBR光纤激光器能够产生两种正交偏振模式的激光,而这两种偏振模式的频率差拍会在射频域形成对温度变化极为敏感的拍频(beatfrequency)。实验结果表明:在20～100℃的温度范围内,激光器拍频随温度的增加呈线性减小,其线性拟合度高达0.99981,拍频灵敏度为0.51063MHz/℃。这种偏振式光纤激光器具有高输出功率、高信噪比、低解调成本和窄输出线宽等特点,有助于构建大规模的光纤有源传感网络。参考近年关于光纤传感网络的报道,提出一种有源光纤环形传感网络的构想。     

Performance improvement of RoF transmission link by using 120° hybrid coupler in OSSB generation

This paper presents an analysis, simulation and comparison of the performance of Optical single sideband radio over fiber system based on a dual drive Mach Zehender modulator using 90° and 120° hybrid coupler including the effects of phase noise from RF signal oscillator and laser source, fiber dispersion. Signal to noise ratio (SNR) is significantly influenced by phase noise from RF signal oscillator. On comparison with conventional 90° hybrid coupler system, the performance of the considered system improves by 0.78 dB in terms of SNR, when RF and laser phase noises are increased.     

A Consideration of an Optical Coupler for Optical Submarine Transmission Laser Redundancy Systems

Theoretical and experimental results are described for a new optical coupler which consists of two laser diodes, two GRIN spherical rod lenses, a polarizing filter, and a single-mode fiber, and which employs laser diode polarization characteristics for an optical submarine transmission laser redundancy system. This optical coupler has two channels at 1.3 μm wavelength. Optical coupler loss values, which include coupling loss, polarization loss, and assembly loss, are 4.9 dB for one laser diode and 5.2 dB for another laser diode. Such loss values are almost the same as the conventional laser diode module loss for a single-mode fiber. This paper describes in detail a laser redundancy system in an optical submarine transmission system, structure and characteristics of an optical coupler, and experimental results on a high bit rate long-haul transmission system using the proposed optical coupler.     

Crosstalk Analysis of a Fiber Laser Sensor Array System Based on Digital Phase-Generated Carrier Scheme

A detailed study on analyzing the crosstalk in a wavelength division multiplexed fiber laser sensor array system based on a digital phase generated carrier interferometric interrogation scheme is reported. The crosstalk effects induced by the limited optical channel isolation of a dense wavelength division demultiplexer (DWDM) are presented, and the necessary channel isolation to keep the crosstalk negligible to the output signal was calculated via Bessel function expansion and demonstrated by a two serial fiber laser sensors system. Finally, a three-element fiber laser sensor array system with a 50-dB channel-isolation DWDM was built up. Experimental results demonstrated that there was no measurable crosstalk between the output channels.     

光纤激光器的相干输出

研究了两路光纤激光的相位锁定和相干输出, 用融锥光纤耦合器实现了两路高掺铒光纤激光之间的相互耦合。提出了在激光器高反射率前腔镜的前面加融锥光纤耦合器的方法构成简单的共振腔, 从而实现两路光纤激光的相干叠加。开展了基于融锥光纤耦合器互注入锁相的两路光纤激光器的相干合成实验, 成功实现了两路光纤激光器的注入锁定, 观察到了波长锁定（中心波长稳定在1549.8 nm, 线宽为0.08 nm）、远场干涉条纹和线宽压缩现象。分析了单个激光器和激光器阵列的斜率效率, 当反射率为70%, 抽运功率均为145 mW时, 获得最大合成功率为127 mW。     

光纤马赫曾德尔干涉曲率传感器的膝关节曲率检测系统研究

在人体运动监测的过程中,膝关节运动信息在中老年慢性疾病的诊断和康复评估方面具有重要意义。研制了一种基于光纤马赫曾德尔干涉曲率传感器（Mach-Zehnder interferometer-based directional bending,MZI-BDB）的膝关节弯曲检测系统。该系统由MZI-BDB传感器、扫频激光光源、光纤耦合器、光纤隔离器、光电探测器及信号处理系统构成。MZI-BDB传感器由偏心光纤和单模光纤错位熔接而成,封装于软硅树脂片内,通过绑带固定于膝关节处。当膝关节屈曲和伸展时,诱导MZI-BDB传感器发生弯曲,传感器内透射光信号干涉场的模场状态发生变化,谐振波长发生漂移,从而对膝关节的弯曲方向和曲率进行监测。MZI-BDB传感器在正向和负向弯曲的测量角度范围为0°~90°;在正向弯曲方向上灵敏度和分辨率分别为5.29 nm/m?1和0.11 m?1;在负向弯曲方向上的灵敏度和分辨率分别为?3.11 nm/m?1和0.12 m?1。实验测试MZI-BDB传感器温度敏感度为0.043 nm/℃,该结果显示传感器对温度的不敏感特性。光电编码器与MZI-BDB传感器同时进行数据的传感采集。实验结果表明:该检测系统和光电编码器验证平台在准确度和响应度上具有一致性。     

基于波导调制器的全保偏光纤微振动传感器

为了解决干涉型光纤传感器中光源频率调制深度与干涉仪光程差的相关性,以及压电陶瓷(PZT)调制的高频限制和非线性效应,设计了全保偏光纤马赫一泽德干涉仪结构,引入保偏光纤波导相位调制器替代常见的光源调制及PZT调制,采用低噪声单频保偏光纤激光器作为光源,通过相位载波零差解调方法,实现了微振动信号的保真拾取.通过波导调制器的引入,增加了系统的灵活性和频响范围,并使灵敏度达到了10-5 rad/Hz1/2量级.     

Receiver analysis for synchronous coherent optical fiber transmission systems

A receiver sensitivity expression applicable for both PSK homodyne and heterodyne optical fiber transmission systems is derived taking account of polarization misalignment, reduced modulation depth, preamplifier thermal noise, power coupling ratio of the fiber coupler, local oscillator excess intensity noise, and reference phase errors. From a comparison of recent studies on system performance degradation due to laser phase noise a generalized expression relating beat linewidth to phase error variance for pilot carrier and Costas phase-locked-loop receivers is defined.