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。     

Radiation Thermometry Based on Photonic Crystal Fiber

Fiber-coupled radiometry allows for the radiometric measurement of high temperatures in environments where there is no line of sight to the target. However, transmission through conventional silica optical fibers degrades rapidly at elevated temperatures, and exotic fibers??such as sapphire fibers??typically cannot be bent. As part of a project to investigate the performance of solid oxide fuel cells, the feasibility of using an alternative fiber, solid-core silica photonic crystal fiber (PCF), was tested. The test system used an Inconel blackbody as a source, and a detection system based on an InGaAs array spectrometer with a wavelength range of 907 nm to 1681 nm. The temperature was determined from the spectrometer signal at particular wavelengths using the Planck relationship. Two tests were performed: (1) long-term high temperature soak tests to measure the drift and noise in thermal radiation levels, in which spectra are sequentially recorded over a long period of time with the blackbody cavity at a constant temperature and (2) temperature dependence tests, whereby thermal radiation spectra are recorded with the blackbody cavity at several temperatures. At 934 °C, the transmission of the PCF decreased at a rate of 0.078 % per hour corresponding to a temperature error of ?0.12 °C per hour. The transmission of conventional silica fiber decreased at a rate of 0.5 % per hour corresponding to a temperature error of ?0.8 °C per hour. While the PCF represents a significant improvement over conventional fiber, it is still not good enough for most practical purposes. At 600 °C there was no observable decline in transmission and there may be applications for PCF in that regime.     

基于结构性改变的光子晶体光纤光栅研究

利用多极法结合耦合模理论对一种基于结构性改变的光子晶体光纤光栅进行了研究,建立了其结构模型,理论分析了此种成栅工艺原理.计算了七层三角形对称排布空气孔包层有效折射率随波长变化情况,比较了不同光子晶体光纤结构成栅效果的差异.研究结果表明,光子晶体光纤包层中空气孔周期性塌缩可以形成光栅,空气孔排布层数,空气孔占空比、空气孔塌缩层数和塌缩程度等参数对光子晶体光纤光栅的传输特性有重要影响,得出了谐振波长和谐振带宽与上述参数之间的变化关系,并给出这种变化关系的解释.     

光纤缠绕式应变传感器

研究了一种可用于机敏复合材料与结构状态监测的本征型强度调制光纤应变传感器,它由两根以上多模光纤相互缠绕绞合形成。分析了该传感器的应变传感原理,得到其既能测量拉应变、又能测量压应变的结论。传感器对应变的响应具有良好的线性和重复性,灵敏度高,无迟滞现象。对植入碳纤维/环氧复合材料内的光纤缠绕型应变传感器的实验结果与理论分析一致,表明该传感器是适合于机敏复合材料与结构状态监测的较为理想的光纤传感器。     

保偏光子晶体光纤模间干涉的研究

针对椭圆芯保偏光纤模间干涉灵敏度和温度稳定性相对较低的缺点,本文提出了采用保偏光子晶体光纤(PM-PCF)来设计模间干涉光纤传感器的方案.对一种保偏光子晶体光纤的模间干涉特性进行了仿真研究,分析了PM-PCF的两个低阶模式LP01模和LP11偶模的传输特性,得到了相对有效折射率与波长的关系以及模间相位差同干涉输出光强分...     

基于Brillouin散射的分布式光纤拉伸应变传感器的理论分析

分布式光纤拉伸应变传感器具有非常重要的应用前景。本文中着重从理论上分析讨论了光纤拉伸应变与由此引起的Ｂｒｉｌｌｏｕｉｎ散射光相对于入射光频移量的变化关系。计算结果表明：其理论和实验数据基本吻合。     

马赫-曾德光纤传感器应变性能实验研究

构建了基于马赫-曾德干涉原理的新型光纤传感器,配合信号采集和数据分析部件组成应变检测系统.在内部粘有光纤传感器的玻璃纤维增强混凝土梁进行弯曲试验时,应用该系统检测了试件的应力应变状态,结果与同步电测数据相符,这说明马赫-曾德光纤传感器性能稳定,测量精度高,在工程结构中的应用前景良好.     

Bragg光栅式应变传感器的传感特性研究

光纤Bragg光栅是一种新型的传感元件,其原理是利用波长解调的方法将被测的信号转化为光栅反射波长的偏移量,同时反射波长不受入射光的功率波动或光路系统损耗的影响。光纤Bragg光栅应变式传感器因此具备良好的可靠性、不受电磁干扰、不易腐蚀,同时最大的优点是在一根光纤上将多个光纤光栅应变传感器串接组成构成阵列开展分布式测量等优点,在逐渐应用于各类力学检测领域。本文着重对光纤Bragg光栅温度和应变的传感特性简要介绍并进行试验分析.     

工程结构光纤应变传感器

研究了一种用于土木工程结构监测的本征型强度调制光纤传感器，其敏感部分是利用光刻技术在多模光纤上形成的齿槽周期结构。详细分析了该传感器原理，首次得到这种传感器既能测量拉就变，也能测量压应变的统一表示公式。传感器对应变的响应具有 线性变和重复性，而且应变灵敏度完全由敏感元结构参数决定。     

Addressing Factors Affecting Fluorescent Signal Collection of a Multimode Photonic Crystal Fiber Fluorometer

A multimode photonic crystal fiber (PCF) fluorometer interrogated by a spectrometer is investigated. By adding a glass tip at the end of the PCF, we found that this fluorometer significantly enhances the fluorescent light collection efficiency (CE). Factors associated with the CE and stray light rejection are addressed. The experimental study verifies the proposed PCF probe based on the consideration of solely meridian rays. However, our further study in this paper shows the significance of skew rays under total internal reflection (TIR), which in fact carry 53% of the total guidable fluorescent signal power and are blocked in our experiment. We highlight that this missing power is strongly associated with the numerical aperture (NA) of each optical component in the system and suggest further improvement on the components in the system. The proposed PCF fluorometer is particularly efficient and cost effective for an immersion medium with a high attenuation.      

Yb^3＋掺杂双包层光子晶体光纤制备研究

本文报道了国内自行研制和制备的以高功率光子晶体光纤激光器为目标的Yb3+掺杂双包层光子晶体光纤.给出了Yb3+掺杂多组分玻璃芯棒和以此为芯的双包层光子晶体光纤的制备流程,工艺和关键技术.对制备的Yb3+掺杂多组分玻璃、双包层光子晶体光纤进行-系列的物理属性、热学和光谱测试,并通过计算分析得到相对优秀的掺杂多组分玻璃配方(Yb3+-(2 mol%)-SiO2(70 mol%)-MgO-CaO-BaO-Li2O-Al2O3(2 mol%)).样品中的Yb3+掺杂双包层光子晶体光纤具有结构规则传光性能良好等优点,为自行开发高功率光子晶体光纤激光器提供材料器件基础.     

光子晶体光纤光栅反射谱及时延特性研究

利用多极法对包层空气孔为正六边形对称结构光子晶体光纤的模式场进行了分析,计算出不同波长下基模的有效折射率,结合使用模式耦合理论和传输矩阵法对基于光子晶体光纤的布拉格光栅特性进行了计算和仿真,对比了常规单模光纤所成光栅与相同光栅周期的光子晶体光纤布拉格光栅反射谱及时延特性之间的差异.在此基础上,对光纤光栅的切趾特性进行了研究,选择不同的切趾函数,得出最佳切趾函数下光栅传输谱.理论计算和仿真结果表明,随波长增加,基模有效折射率下降,光栅谐振波长出现蓝移,采用啁啾化处理后,10 cm长光子晶体光纤光栅可以提供1 200 ps以上的线性时延.     

Single-Mode Birefringent Fiber Frequency-Modulated Continuous- Wave Interferometric Strain Sensor

A practical single-mode birefringent fiber strain sensor is demonstrated. The sensor is based on optical frequency-modulated continuous-wave (FMCW) interference and consists of three lengths of single-mode birefringent fiber. Two fibers are used as the leading fibers, while the third fiber that locates in the middle and has a 45$^{circ}$ rotation of principle axes is used as the strain sensing fiber. The strain is determined by measuring the phase shift of the beat signal produced by the two beams in the sensing fiber. The advantages of the sensor include high resolution, large dynamic range, long gauge length, long leading fibers, simple configuration, and immunity from the environmental influence.      

棱镜耦合光子晶体表面波及其传感特性研究

构造一种棱镜耦合一维光子晶体结构,利用传输矩阵方法对该结构中光的传输特性进行研究.结果表明:光在这种棱镜耦合一维光子晶体结构中传播时,会在光子晶体表面产生非辐射传播模,即表面波,而且在反射谱中表面波所在的角度位置、反射率的大小以及反射峰的半峰全宽受到一维光子晶体的介质折射率和介质厚度的调制.此外,表面波对应的角度位置对...     

一种基于光子晶体结构的新型MEMS红外光源

结合光子晶体和表面等离子体共轭（surface plasmon resonance，SPR）技术，研究了一种新型的MEMS红外光源．相比传统的红外光源，该新型光源具有红外光谱窄、红外发射峰位置可调等优点．该光源衬底材料为硅，然后在硅表面形成SiO2-Cr-Au结构，并在Si-SiO2-Cr-Au结构表面形成刻蚀深度为2pm、孔间距分别为7μm和8μm（孔直径分别为3．5μm和4μm）等不同的周期性排列圆孔的光子晶体结构．采用有限元时域分析（finite-difference time-domain，FDTD）软件模拟和傅里叶红外光谱仪实际测量的结果表明，该新型MEMS红外光源具有窄的波峰，其反射光谱波谷波长和圆孔间距相近．通过理论推导和FDTD软件模拟，研究了光源光子晶体结构中圆孔深度和透射光谱波峰强度关系．结果表明，圆孔深度为2μm的结构比3μm结构的透射强度更强．透射强度与圆孔深度h在一定范围近似为倒数平方关系，即在一定范围内圆孔越深，透射越弱．     

基于异质双周期结构光子晶体加速度计的设计

对于异质双周期结构的光子晶体而言,不需要掺杂即可形成多条透射谱。理论结果显示,在实际应用范围内,透射率与光子晶体所受的轴向应力呈简单的线性关系。据此,设计了一种单悬臂梁结构的多量程、超灵敏的宽频带加速度计。在单悬臂梁根部所受应力最大处,用异质双周期光子晶体替代以往的压敏电阻,只需检测出透射光强与入射光强的比值,即可测出加速度。ANSYS软件仿真结果表明,当透射光强改变万分之一时,该加速度计可以感知0.01gn的加速度变化,测量量程可达100gn。从模态分析图中可以看到该加速度计可以稳定地工作,可用在自控、车辆、测试等领域。     

啁啾光子晶体光纤光栅反射谱和时延特性研究

用有限元法和传输矩阵法,对基于包层空气孔为柚子型结构的光子晶体光纤啁啾光栅的反射谱进行了理论分析。通过对均匀光栅仿真结果与实验结果的对比,可知此方法是可行的。研究表明光子晶体光纤的啁啾光栅有多个明显的反射峰,并且分析了啁啾系数、折变量对各谐振峰带宽和反射率等的影响。计算结果显示,随着啁啾系数和折变量的增大,光栅反射谱呈规律变化,当啁啾系数增大到一定程度时几个反射峰会连到一起,形成一个大的反射带宽。同时对光栅基模反射谱对应的时延特性进行了研究,可知其同样具有比较平滑的时延曲线,可以用于色散补偿。     

高非线性光子晶体光纤布里渊散射谱及温敏特性

利用光子晶体光纤中相向传播的两束激光之间的受激布里渊散射光放大作用原理,通过实验研究了光子晶体光纤中布里渊散射谱和布里渊频移随温度的变化特性,当入射激光在波长为1 548 nm、温度为25℃时,光子晶体光纤的受激布里渊散光相对于入射光移频量为9.795 GHz,布里渊谱线宽度为19 MHz,频移温度系数为1.33℃/M...     

Analysis of Temperature-Dependent Optical Properties in 1D Ternary Superconducting Photonic Crystal with Mirror Symmetry

The temperature dependence of the defect mode in a 1D ternary superconducting photonic crystal (PC) with mirror symmetry was theoretically investigated by simultaneously considering thermal expansion effect and thermal-optical effect. Three different materials H (high-refractive index dielectric), L (low-refractive index dielectric), and S (superconducting material) are used to construct the ternary superconducting PC structure. For comparison, six structures are discussed. It is found that the structure (HLS) ^N (SLH) ^N has the highest temperature sensitivity. Here, N is the number of periods. The average change in the central wavelength of the defect mode is 31.18 nm/K as the thickness of superconducting layer is 50 nm. Thus, based on the structure (HLS) ^N (SLH) ^N , a low temperature sensor with higher sensitivity can be designed to realize the low temperature sensor.