TFBG的Fabry-Perot干涉型纵向微位移传感研究

提出了一种利用光纤Fabry-Perot(F-P)干涉结构的微位移传感器,该F-P干涉结构是由双倾斜光纤光栅(tilted fiber Bragg grating,TFBG)沿轴向错开一定距离构成空气腔形成的.入射光经双TFBG及其高反射端面往返传播,从而构成F-P干涉结构.光纤沿纵(z轴)向移动时,F-P腔的腔长发生变化,致使干涉光谱的自由光谱范围随之产生变化.实验验证,该传感器在0~115μm的测量范围内获得了高达0.475nm/μm的灵敏度,较之前提出的光纤光栅型传感器灵敏度提高了近3倍.     

光子晶体光纤Fabry-Perot结构温度传感特性研究

提出了一种将光子晶体光纤(Photonics Crystal Fiber,PCF)与单模光纤(Single Mode Fiber,SMF)拼接而成的法布里-珀罗干涉(Fabry-Perot Interferometer,FPI)传感器,形成SMF-PCF-SMF结构,其中PCF为F-P腔。反射谱波长周期为2. 18 nm,条纹对比度达到13. 12 d B。研究了FPI传感器的温度响应,在50～400℃分别进行了升温和降温实验,波长灵敏度为12. 3 pm/℃,线性度大于0. 993。该传感器具有交叉灵敏度低、温度稳定性好、线性度高等优点,可用于工业生产、航空航天、生物医学等温度传感领域。     

腔长损耗对非本征F-P腔光纤传感器的影响

根据光学法布里-珀罗(F-P)腔基本原理,运用单模光纤能量散射模型分析了腔长损耗对非本征F-P腔输出光强度的影响.实验过程中所用的F-P腔由单模光纤端面和弹性硅片组成.实验结果表明,非本征F-P腔输出光强幅度随腔长增大逐渐衰减,其输出特性曲线中不同部分相同周期的线性工作区间却对应不同的测量量程和灵敏度,所以强度型光纤F-P腔传感器初始腔长应基于传感器的性能指标进行选取.     

光子晶体光纤F-P干涉式高温传感器研究

本文提出一种用于高温测量的光子晶体光纤F-P干涉传感器,通过熔接机放电使无截止单模光子晶体光纤(ESM-PCF)一个端面完全塌陷,然后再将其与单模光纤(SMF-28e)熔接起来,最后按照设计长度切断ESM-PCF。由于在熔接点处ESM-PCF完全塌陷使其模场直径扩大,减小了与SMF-28e的模场失配损耗,并提高了熔接面的反射光强。这种方式制作简单,相对于以往的光子晶体光纤F-P干涉传感器具有更高的干涉光强度。实验结果表明,该传感器测量温度可达1100℃,温度灵敏度为29.4nm/℃,可以预见这种结构稳定、线性度好的全光纤传感器在机械、航空、冶金领域等具有一定的潜在应用价值。     

膜片式光纤动态压力传感器的研制

为了更好地满足动态压力的测量需求,研究了一种基于法布里-珀罗（Fabry-Perot,F-P）干涉原理的膜片式光纤动态压力传感器。从理论上分析了多个反射面对F-P腔光谱的影响,提出了得到单一F-P腔的方法。进而采用机械研磨的方式对传感器膜片外表面进行粗化加工,有效解决了由多个反射面带来的光谱复杂问题。对传感器进行静态压力和动态压力标定试验,结果表明：传感器性能良好,在0~200 kPa（表压）范围内的静态压力测量误差小于等于0.5 %FS;在20~2500 Hz范围内,传感器的幅值灵敏度相对误差优于±10%。     

基于端面镀膜的Fabry-Perot光纤传感器研究

应用模式耦合理论计算了外腔式Fabry-Perot（F-P）干涉型光纤传感器的输出光强与F-P腔长的关系。对组成F-P腔的光纤端面进行了磨平抛光及镀多层电介质膜处理，使光纤端面反射率为70%，从而提高了传感器的抗干扰能力，简化了探测系统。将该传感器与电阻就变片作对比测量实验，其结果完全一致。     

温度对石墨烯膜光纤F-P声压传感器灵敏度影响研究

石墨烯具有优异的机械、电学与光学等传感特性,有希望成为下一代可穿戴电子设备的功能敏感材料。石墨烯膜Fabry-Perot(F-P)声压传感器具有高灵敏度、小型化和抗电磁干扰等优点,但会受到温度漂移的影响。温度对传感器的影响主要体现在F-P腔长变化,引起工作点漂移,导致传感器光学灵敏度发生变化,以及改变石墨烯膜预应力。本文制备了石墨烯膜光纤F-P声压传感器探头,通过声压测试表明,温度改变了悬浮石墨烯膜的机械力学特性,在1 kHz处使其机械灵敏度由1.80 nm/Pa提高至2.44 nm/Pa。     

保偏微结构光纤光栅 F-P腔折射率传感特性分析

针对提高光纤光栅折射率传感器抗干扰能力以及增加反射率的需求,本文提出了一种基于Fabry-Perot腔的保偏微结构光纤(PM-MOF)布拉格光栅折射率传感器.根据传榆矩阵法和有限元方法,分析了微结构光纤光栅F-P腔中被测物折射率与F-P腔反射谱中两个偏振模谐振波长差的关系,在此基础上讨论了中心孔直径、F-P腔长度等参数对传输特性的影响.研究结果表明,随着空气孔中填充物折射率的增加,保偏微结构光纤光栅F-P腔的两个偏振态的谐振波长差将逐渐减小;F-P腔的干涉作用使反射率较单个光栅有很大提高,便于长距离传输和实时解调;两个偏振模对外界干扰具有相似的响应,因此该传感器具有更强的抗干扰能力.本文研究结果为保偏微结构光纤光栅在折射率传感器及其生物传感器方面的应用提供了理论依据.     

应变、温度、位移测量光纤光栅传感器的研究

本文介绍了集成式Bragg光纤光栅(FBGI)传感器的结构及其应用该传感器测量应变、温度、位移的基本原理.利用FBGI和相干性干涉信号解调方法实现了用一个传感器同时测量三个参量.实验结果表明温度精度达±1℃,应变精度为±30u ε,位移分辨率达1nm,测量重复性好.     

埋入光纤进行复合材料中的应变测量

由于光纤传感器所具有的特点, 把光纤埋入复合材料内部进行应变测量, 从而监测复合材料的性能改变, 是随着智能复合材料结构的研究而发展起来的一项新技术, 本文用弱波导理论的有关结果研究了光纤在受到力作用时, 光纤应变和其中传输光的位相改变之间的关系, 计算了Corning 光纤在轴向应力作用下的应变-位相灵敏度, 为形成干涉型光纤传感器提供理论基础; 同时给出了单向受力情况下的实验验证, 分析了误差原因。      

Optical fibre Fabry–Perot relative humidity sensor based on HCPCF and chitosan film

Abstract

An optical fibre Fabry–Perot interferometer (FPI) sensor for relative humidity (RH) measurement is proposed. The FPI is formed by splicing a short section of hollow-core photonic crystal fibre(HCPCF) to single mode fibre and covering a chitosan film at the end of HCPCF. The refractive index of chitosan and film thickness will change with ambient RH, leading to the change in the reflected interference spectrum of FPI. RH response of the FPI sensor is analysed theoretically and demonstrated experimentally. It shows nonlinear response to RH values from 35 to 95%RH. The interference fringe shifts to shorter wavelength as RH increases with a maximum sensitivity of 0.28 nm/%RH at high RH level. And the fringe contrast also decreases as RH increases with an available maximum sensitivity of 0.5 dB/%RH. The sensor shows good stability and fast response time less than 1 min. With its advantages of compact structure, good performance, simple and safe fabrication, the proposed optical fibre FPI sensor has great potential for RH sensing.     

Temperature-Independent Strain Sensor Based on a Hi-Bi Photonic Crystal Fiber Loop Mirror

This work presents an optical sensor based on a highly birefringent photonic crystal fiber (Hi-Bi PCF) loop mirror. The length of the sensing head is 380 mm and its corresponding wavelength spacing between two interferometer minima is 8 nm. The optical sensor was characterized in strain and in temperature with an uncoated Hi-Bi PCF and with an acrylate coated Hi-Bi PCF. Different results for strain and temperature sensitivity were obtained. Relatively to the strain measurement, the sensor with the uncoated Hi-Bi PCF presents slightly less sensitivity (1.11 ) when compared with coated Hi-Bi PCF (1.21 ). For the temperature measurement and with the uncoated Hi-Bi PCF, the optical sensor is insensitive to temperature (0.29 pm/K).     

Microbubble based fiber-optic Fabry-Perot interferometer formed by fusion splicing single-mode fibers for strain measurement

We demonstrate an all-fiber optical Fabry-Perot interferometer (FPI) strain sensor whose cavity is a microscopic air bubble. The bubble is formed by fusion splicing together two sections of single-mode fibers (SMFs) with cleaved flat tip and arc fusion induced hemispherical tip, respectively. The fabricated interferometers are with bubble diameters of typically ~100 μm. Strain and temperature sensitivities of fabricated interferometers are studied experimentally; a strain sensitivity of over 4 Pm/με and a thermal sensitivity of less than 0.9 Pm/°C is obtained.     

Highly sensitive refractive index sensor based on two cascaded special long-period fiber gratings with rotary refractive index modulation

We present a refractive index (RI) sensor based on a fiber Mach-Zehnder interferometer (MZI) formed by two cascaded special long-period fiber gratings (LPFGs) with rotary refractive index modulation (RLPFGs), in which the coupling occurred between the guided mode and the high-order asymmetric cladding mode. The experimental results show that the RI sensitivity of a refractometer with an interaction length of 40?mm is up to 58.8?nm/RI in the range of 1.3344 to 1.3637, which is 3.5 times higher than that of an MZI formed by two normal LPFGs. The temperature sensitivity for the same parameters of an RLPFG-MZI is about 0.03?nm/°C. Such a kind of high-sensitivity, easy-to-fabricate and simple-structure interferometer may find applications in the chemical or biochemical sensing fields.     

光纤传感技术应用于轧制力测量的研究

中介绍一种光纤法布里-珀罗干涉式应变传感器，并对其应用于轧制力测量进行了研究。详细分析了该传感器的原理，导出了轧制力与光纤干涉腔反射光强的关系表达式。理论分析和实验结果表明，用这种光纤应变传感器测量轧制力是切实可行的，与传统的测量轧制力的方法比较，具有结构简单，抗干扰能力强，测量准确度高，灵敏度高等优点。     

Embedded fiber-optic Fabry-Perot ultrasound sensor

A fiber-optic ultrasound sensor is presented. The sensor consists of a continuous length of single-mode optical fiber with a built-in Fabry-Perot interferometer. The acoustic pressure produces changes in the index of refraction along the interferometer cavity through the strain-optic effect, thus modulating the reflected power of the light propagating in the fiber. The dielectric internal mirrors that form the interferometer are fabricated by joining a fiber coating with a TiO(2) film at one end to an uncoated fiber by electric arc fusion splicing. Experimental results have been obtained for sensors embedded in plastic and graphite composite materials, using ultrasound waves in the range from 100 kHz to 5 MHz. Values for the optical phase shift amplitude as large as 0.5 rad were obtained at an acoustic frequency of 200 kHz for a 1.1-cm-long interferometer embedded in plastic.