新型耐高温FBG传感系统研究

为解决传统的高温传感器不能满足对电解Al槽温等高温环境的实时在线测量问题,提出了基于波长调制的光纤Bragg光栅（FBG）高温传感系统,设计了一种新型封装结构的耐高温FBG传感头,具有体积小、灵敏度高和线性度好等特点;采用了基于InGaAs图像传感器衍射解调技术对光反射波长进行解调,缩短了系统的响应时间,提高了测量精度...     

基于衍射解调的新型光纤光栅高温传感网络

基于光纤布拉格光栅(FBG)高温传感特性,设计了一种基于波长调制的耐高温光纤光栅传感网络。系统设计了新型封装结构的耐高温光栅传感头。并针对传统FBG传感网络结构可靠性低的缺点,设计了一种高可靠分布式传感网络结构。采用InGaAs图像传感衍射解调技术对光反射波长进行解调。20～290℃范围测试实验表明,所设计的传感网络温度响应曲线平均线性度达0.9991,灵敏度为0.0258nm/℃,测量精度达±0.6℃,响应时间小于16s,稳定性高,适用于实际工作环境中的高温测量。     

基于光纤腔衰落解调技术的光纤光栅传感研究

采用弱调制长周期光纤光栅(LPG)作为基本传感器件,将其接入到光纤谐振腔中,利用光纤腔衰落(FRD)技术,通过检测脉冲激光的衰落时间实现光纤光栅传感的波长解调.进行了0～100℃温度和0～1000με应变实验,波长解调范围为10 nm.     

基于F-P滤波器光纤光栅解调系统

提出并实验演示了一种基于F-P可调滤波法对光纤光栅波长解调的新方案,利用参考光栅温度与其反射波长关系来检测传感光栅的波长移动量,该解调方法成本低.实验结果证明:采用此方法的解调系统波长测量精度达到5pm以上,有很高的稳定性,具有实际应用价值.     

波长调制晶体吸收温度传感器原理

晶体吸收式光纤温度传感器是利用半导体晶体的光吸收与温度的依赖关系制作的温度传感器,体积小,成本低.目前对其研究都是基于光强调制,光强调制本身受光源扰动和光路扰动影响较大,致使传感器测量精度低,稳定性差.为提高晶体吸收式光纤温度传感器的测量精度及稳定性,提出利用波长调制制作传感系统的方法,从理论上予以仿真,并给出了半导体砷化镓材料的透射光谱曲线随温度变化的实验结果.     

基于光纤激光器的全光光纤光栅传感理论分析

为了提高光纤光栅传感系统的可兼容性和抗干扰能力,提出了在环形腔光纤激光器中,采用基于光纤布拉格光栅的法布里-珀罗谐振腔(F-P)对传感元进行波长寻址的理论模型,并利用悬臂梁技术对解调光纤光栅进行波长调谐.利用全光传感系统,具有分辨率高、插入损耗小、兼容性好等优点;锁定某一传感光栅的信号后,利用反馈系统对感测信号进行自动跟踪解调.利用一个传感光栅和一个解调光栅进行实验验证,得到了位于传感光栅中心波长1554.32 nm的激光输出,证实了系统的波长可解调能力.     

边缘滤波温度传感研究

利用基于长周期光栅的边缘滤波解调方法,在给出波长解调原理的基础上,对裸光纤光栅和毛细钢管封装的光栅进行了温度传感实验研究.实验结果表明,在所测温度范围内,光纤光栅呈现良好的线性关系,且封装式传感头线性度更优.而后利用封装式探头进行解调实验研究,表明经边缘滤波解调后系统的精度进一步提高.     

长距离光栅阵列温度测量系统设计与实现

基于光栅阵列温度测量系统,设计了一种适用于长距离温度监测场景的温度解调系统,通过分布式光纤拉曼放大器的引入对传感链路提供分布式的放大效果,并对回光信号进行了前置放大,有效补偿了信号长距离传输面临的损耗问题.利用光纤光栅的中心波长与温度变化的关系实现了温度解调,系统的空间分辨率可达1 m,在55 km传感距离处实现了温度...     

基于Labview的光纤光栅波长解调系统

提出了一种基于Labview的数字化光纤光栅信号解调系统,实现了光纤光栅应变传感波长解调.采用Labview编写程序实现信号的实时采集、处理、显示,解决了普通光纤光栅解调设备成本高,体积大等难题;进行了基于上述系统的光纤光栅应变传感实验研究.实验结果表明,反射谱线中心波长漂移量与轴向应力具有很好的线性关系,当应力达到60με时,光纤Bragg光栅(FBG)对应的波长漂移量约为1.90 nm.     

基于拍频解调的光纤激光温度传感系统

为了提高光纤激光器的温度灵敏度和数据完整性，提出了一种基于拍频解调的光纤激光温度传感系统。利用光纤激光谐振腔中的光纤布拉格光栅（FBG）进行温度传感，将FBG的波长变化依次转变为谐振腔内的波长变化和光纤激光器拍频信号的频移变化，大幅提高了系统的灵敏度。通过Python程序实现秒级数据自动采集及保存，提高了工作效率。用矩形框中心点位置法代替直接寻峰值法对温度信号进行解调，可避免频率抖动较大引起的误差。相比光学解调技术，该系统利用成熟的电学解调技术解调，无需昂贵的波长解调仪，降低了解调成本。实验结果表明，该系统具有较高的灵敏度和测量精度，平均灵敏度为74.087 kHz/℃，测量精度为0.47×10-3℃。     

基于保偏光纤模式干涉的温度传感技术

基于Sagnac光纤干涉仪偏振非互易的光纤温度传感器的理论、方案和相关技术,利用光强度直接测量的信号检测技术,实现了单点温度传感并进行了实验验证.实验和测试表明:这种温度传感器达到了0.01℃的温度分辨率和稳定性,通过改变温度传感头的长度和传感保偏光纤的双折射率,可方便地调节其测量范围.同时又提出了一种新的反射型保偏光纤温度传感方案并研制出微小型保偏光纤温度传感头.在此基础上,实现了多点温度测量,研制出大型变压器绕组温度监控用多点温度传感系统,在0～200 ℃的温度范围内达到了0.5℃的测量精度和分辨率,研制的传感头满足高电压绝缘和热油、热蒸汽的恶劣环境要求.     

Study of Semiconductor Multilayer Structures by Cathodoluminescence and Electron Probe Microanalysis

Complementary nondestructive electron probe methods were used for characterization of semiconductor multilayer structures. We used cathodoluminescence and electron probe microanalysis for studying laser heterostructures based on GaAs/AlGaAs/InGaAs/GaAs and InGaN/GaN. Our latest investigation showed the possibility of measuring the composition of buried layers and determining the composition of thin nanoscale layers by electron probe microanalysis. Simultaneous use of local cathodoluminescence is very useful for defect study in bulk semiconductors, epilayers, and multilayer heterostructures. This method allows characterization of charge-carrier transport properties and diffusion length in multilayer structures, using the variation of the electron beam energy and calculation of the electron penetration depth.     

Design of distributed Raman temperature sensing system based on single-mode optical fiber

The distributed optical fiber temperature sensor system based on Raman scattering has developed rapidly since it was invented in 1970s. The optical wavelengths used in most of the distributed temperature optical fiber sensor system based on the Raman scattering are around from 840 to 1330 nm, and the system operates with multimode optical fibers. However, this wavelength range is not suitable for long-distance transmission due to the high attenuation and dispersion of the transmission optical fiber. A novel distributed optical fiber Raman temperature sensor system based on standard single-mode optical fiber is proposed. The system employs the wavelength of 1550 nm as the probe light and the standard communication optical fiber as the sensing medium to increase the sensing distance. This system mainly includes three modules: the probe light transmitting module, the light magnifying and transmission module, and the signal acquisition module.     

温度补偿型光纤光栅加速度传感探头结构设计

采用可调光纤F-P滤波器技术设计了一种光纤光栅加速度传感系统。提出了一种温度补偿型光纤光栅加速度传感探头,探头弹性系统主要有惯性质量块、双弹簧片、钢管等组成。探头采用不受力光纤光栅法进行了温度补偿。该探头具有结构简单,不受电磁干扰,不受光路功率波动和相位噪声影响等优点,且能自动进行温度补偿。     

基于双光纤光栅的加速度传感探头结构的设计

分布式光纤光栅加速度传感技术对微弱振动测量分析及其故障诊断具有重要的实用价值。采用副载波调频、波分复用技术提出了一种分布式光纤布喇格光栅加速度测量系统,并进行了基于双光纤布喇格光栅的加速度传感探头结构的设计。该传感探头具有尺寸小,质量轻,不受电磁干扰等优点,有较高的测量灵敏度和分辨率,而且能自动消除温度噪声和相位噪声的影响。     

Microchannel gate temperature analysis

Photoemission spectra of a GaAs gate material of a metal semiconductor field effect transistor (MESFET) were analyzed to nondestructively assess the submicron-size local gate temperature. Utilizing the micromanipulator, the laser beam was precisely adjusted to probe the exact position of the device gate. The emission spectral bands due to the interaction among photons, free excitons and impurity bound excitons in GaAs gate materials were measured and identified both at 299.1 K and 84.8 K. The shift of the band was found to be 16.30 meV for the free excitons when the device was not powered, while the band shift of the gate was 7.38 meV when the device was powered at 84.8 K. Simple first order calculations based on the theory of temperature shift of the bound excitons, predicts an inversely proportional relationship between the emission bandshift and temperature. Measurements using this technique found an increase of 97.0 K.     

Current-voltage characteristics of silicon-doped GaAs nanowhiskers with a protecting AlGaAs coating overgrown with an undoped GaAs layer

A technique for measurement of longitudinal current-voltage characteristics of semiconductor nanowhiskers remaining in contact with the growth surface is suggested. The technique is based on setting up a stable conductive contact between the top of a nanowhisker and the probe of an atomic-force microscope. It is demonstrated that, as the force pressing the probe against the top of the nanowhisker increases, the natural oxide layer covering the top is punctured and a direct contact between the probe and the nanowhisker body is established. In order to prevent nanowhiskers from bending and, ultimately, breaking, they need to be somehow fixed in space. In this study, GaAs nanowhiskers were kept fixed by partially overgrowing them with a GaAs layer. To isolate nanowhiskers from the matrix they were embedded in, they were coated by a nanometer layer of AlGaAs. Doping of GaAs nanowhiskers with silicon was investigated. The shape of the current-voltage characteristics obtained indicates that introduction of silicon leads to p-type conduction in nanowhiskers, in contrast to n-type conduction in bulk GaAs crystals grown by molecular-beam epitaxy. This difference is attributed to the fact that the vapor-liquid-solid process used to obtain nanowhiskers includes a final stage of liquid-phase epitaxy, a characteristic of the latter being p-type conduction obtained in bulk GaAs(Si) crystals.     

GaAs单片集成激光器驱动电路在片测量

用多触头微波探针 ,对 Ga As单片集成激光器驱动电路芯片进行了在片测试和筛选 ,测得芯片频率响应带宽为 3.8GHz.使用高速增益开关半导体激光器作为采样光脉冲源 ,采用了背面直接采样方式建立了电光采样测试仪 .检测了 Ga As单片集成激光器驱动电路芯片内部点的高速电信号波形 .     

The superlattice barrier capacitor: A structure for the investigation of heterojunction interfaces

A symmetric n- GaAs/AlAs-GaAs superlattice/n- GaAs structure has been fabricated and electrical measurements made between 300 and 77 K. At 238 K and below, the C-V characteristics were clearly symmetric, in good agreement with theory. Such a structure can be used as a sensitive probe of the interface defects at the "normal" and "inverted" heterojunction interfaces associated with the barrier. Furthermore, the highly nonlinear C-V characteristic of this symmetric semiconductor capacitor near-zero bias may have unique applications.     

GaAs/Si/AlAs异质结的DLTS实验研究

利用深能级瞬态谱(DLTS)技术研究了Si夹层和GaAs层不同生长温度对GaAs/AlAs异质结晶体品质的影响.发现Si夹层的引入并没有引起明显深能级缺陷,而不同温度下生长的GaAs/Si/AlAs异质结随着温度的降低,深能级缺陷明显增加,并进行了分析,得到深能级是由Ga空位引起的,在600℃时生长的晶体质量最佳.