谱带吸收式光纤温度传感器

本文提出了一种新颖的半导体谱带吸收式光纤温度传感器系统结构.分析了半导体谱带吸收式光纤温度传感器的原理,推导了其数学模型.该传感器用反射式传感结构,以砷化镓半导体材料作为温度敏感元件,并利用除法器消除了传感器光源的波动及光纤的连接损耗,使传感器具有结构简单、抗环境干扰、高可靠性特点.文中对传感器的整个系统进行了设计和分析,并进行了实验测试,实验结果显示:该传感器在－20～110℃的温度范围内有1℃的测量精确度,并且温度从110℃降到15℃时的时间响应为25s.     

吸收式光纤温度传感器的研究

提出了一种利用半导体光吸收谱随温度变化原理设计的半导体吸收式光纤温度传感器.该传感器用GaAs晶片作为温度敏感元件，以光纤作为传光介质，发光二极管作为光源，光电管作为光电转换器件.利用双光束补偿原理,消除了由于光源不稳定产生的干扰.研制出的光纤传感器具有体积小，结构简单，抗电磁干扰，灵敏度高等优点.实验表明:该传感器在－20℃~85℃温度范围内可以达到0.1℃的准确度，可以实现强电磁干扰下的高空飞行器内环境温度的测量.为进一步实现光传飞控系统中的温度测控奠定了基础.     

双程前向近高斯型掺铒超荧光光纤光源的实验研究

研究了输出谱型为近高斯型的掺铒超荧光光纤光源,分析了高斯型光谱的自相干函数和影响平均波长稳定性的因素.采用双程前向光源结构,通过选择铒纤长度获得高斯型光谱输出,同时调节泵浦功率来优化铒纤的本征温度系数对光源的影响,得到铒纤长度10.05 m,泵浦功率为172 mW时,整体光路（除半导体泵浦激光器及其驱动电源）在全温－40 ℃~60 ℃测试条件下平均波长稳定性为66.651 ppm的近高斯型掺铒光纤光源.     

塑料光纤直径测量系统

提出了以可编程逻辑器件为核心的塑料光纤直径在线测量系统,阐述了其工作原理。系统使用发光二极管作为光源、高精度线阵CCD作为图像传感器,简化了光学部分;应用EPLD和双口RAM,提高了信号处理效率;设计了提高测量精度的单片机数据处理算法。实验表明系统的测量范围为0 26～3mm,测量精度在10μm以内,满足塑料光纤直径测量要求。     

波长扫描极值解调法实现光纤光栅应变和温度传感的测量

本文用可编程调谐光纤光栅环行腔激光器作扫描光源,采用波长扫描极值传感解调法对光纤光栅应变及温度进行了测量。应变测量范围为±2440με,灵敏度为0.016step/με;温度测量范围达608℃,灵敏度为0.13step/℃。     

基于窄线宽扫频光源的高分辨率阵列式光纤光栅温度传感系统

高精度温度传感器在地球物理、海洋科学、石油化工等领域具有广泛应用。针对传统光纤光栅温度传感器分辨率较低的问题,提出一种基于光纤光栅的高精度多点复用温度传感系统,该系统采用封装好的不同中心波长的π相移光纤光栅作为温度敏感单元,以扫频激光器和波分复用技术检测各光纤光栅谐振波长,并引入氰化氢标准气体吸收室作为波长参考,用非平衡马赫-曾德尔干涉仪补偿光源扫频过程中的非线性,以提升波长测量精度。实验实现了对10个温度传感探头的同时探测,温度分辨率达到10^-4℃水平,测量范围达到0～100℃。该光纤光栅温度传感系统在高精度温度测量领域具有广阔的应用前景。     

反射式光纤温度传感器

本文根据半导体GaAs材料带隙随温度变化的原理,对采用单根光纤作双向传输光信号的反射光纤温度传感器进行了试验研究。由微型计算机控制的光纤测温系统的测温范围为0～150℃精度±1℃,分辨率0.2℃。     

半导体光纤温度传感器

本文利用半导体材料的吸收光谱随温度变化的特性,研制了数字显示光纤测温仪。经过反复试验,该仪器在-20°～200℃温度范围内的测温精度为±2℃。     

带宽调制型单光纤光栅温变无补偿位移传感

报道了利用反射谱带宽调制和光强差分探测技术实现单一光纤光栅温变无补偿位移精确测量的新方法。设计了一种结构新颖的曲臂梁位移传感装置,结合光波导理论与材料力学原理分析了光纤光栅在高斯应变作用下光栅反射谱侧向梯度展宽的成因,理论推导了特殊结构梁在外力作用下光栅反射谱带宽/反射光强与压力之间的响应关系。光栅反射谱侧向梯度展宽的同时反射光强线性增加,利用光强差分检测方法消除光源出光抖动的影响,提高了位移测量精度。基于带宽调制的光纤光栅位移传感方法免受温度变化的影响,在-10℃~80℃的温度变化范围内,测量误差小于1.2%,实现了单光纤光栅温变无补偿位移测量。     

测量转动体位移的光纤传感器的研究

本文报道了采用光学三角漫反射技术来测量转动体位移的光纤传感器从理论上推导了该位移是漫反射产生的光脉冲的某些时间间隔之比的线性函数,实验上得到了7～34mm的测量范围,在该测量范围内误差小于1%.该种测量方法测得的位移与转动体转速无关,与光源强度无关,传感头结构简单,测量范围大,线性度好。本文还对它的应用进行了讨论。     

海水盐度和温度实时检测的新型光纤传感器研究

提出了一种新颖的用于海水温度和盐度同时实时探测的光纤传感器系统。分别利用半导体材料吸收光谱的临界极限值随温度变化发生移动而导致出射光强改变的特性和待测液体盐度变化引起传输光折射角改变导致接收端光线偏移的性质，通过反射式的结构设计和线阵排列的接收光纤信号传输至海面以上，并由CCD实现对光强峰值信号及其偏移量的采集。传感器由一直角棱镜、本征GaAs单晶体薄片、装有参考液和待测液的水槽、接收光纤阵列等部分组成。理论分析和仿真结果验证了传感器设计的可行性。     

基于阵列波导光栅的边缘滤波温度解调系统

为克服传统阵列波导光栅解调系统体积大、价格昂贵等问题,提出了以窄带光源为输入光源,采用边缘滤波和阵列波导光栅相结合的解调方案,实现对增敏封装后的光纤光栅温度传感器进行温度解调实验。以窄带光源作为输入,通过边缘滤波的方法使得温度传感器反射谱的中心波长偏移程度与解调光路输出光强的变化相对应,利用阵列波导光栅的波分复用实现多传感器同时测量,实现了多传感器多通道的分布式测量,实验结果表明:解调系统的波长解调范围为1 545.30 nm～1 560.50 nm,对35 ℃～42 ℃的温度范围进行检测,波长解调精度为±5.34 pm,温度测量误差可达±0.1 ℃。     

Ti离子注入和退火对ZnS薄膜结构和光学性质的影响

利用真空蒸发法在石英玻璃衬底上制备了ZnS薄膜,将能量80 keV,剂量1×10¹⁷ cm^-2的Ti离子注入到薄膜中,并将注入后的ZnS薄膜进行退火处理,退火温度500—700 ℃.利用X射线衍射（XRD）研究了薄膜结构的变化,利用光致发光（PL）和光吸收研究了薄膜光学性质的变化.XRD结果显示,衍射峰在500 ℃退火1 h后有一定程度的恢复;光吸收结果显示,离子注入后光吸收增强,随着退火温度的上升,光吸收逐渐降低,吸收边随着退火温度的提高发生蓝移;PL显示,薄 关键词： ZnS薄膜 离子注入 X射线衍射 光致发光     

玻璃中CdSeS纳米晶体的室温光致发光谱

对掺有过饱和的镉、硒和少量硫的玻璃在500～800℃分别退火4h,生长了不同尺寸的CdSe_1-xS_x纳米晶体。测量了纳米晶体的室温吸收光谱和光致发光(PL)光谱,550℃生长的样品在300～800nm的范围没有观察到吸收和发光峰,表明温度低于550℃玻璃中不能形成纳米晶体。生长温度在600～650℃,纳米晶体的PL光谱主要为两个宽的发光带,即带边激子发光带和通过表面态复合的发光带。随着生长温度的升高,带边复合发光的蓝移减小,通过表面态的发光逐渐消失,并出现了叠加于宽发光带上的一系列明显的弱发射峰。不同温度生长的样品中,叠加峰的能量相同。同一样品中叠加峰的能量不随激发光波长的变化而变化。     

Fabrication and comparison of thermochromic material-based fiber-optic sensors for monitoring the temperature of water

In this study, we explored the feasibility of developing two types of fiber-optic temperature sensors that can measure the temperature of water. One uses a thermochromic material such as Lophine, whose optical absorbance changes according to the thermal variation. The other uses a thermochromic pigment that gradually loses its own color through heat absorption. We measured the change in the intensity of the reflected light, which was due to the variation of the optical property of Lophine and pigments, with thermal variation. The relationship between the temperature of water and the output signal of the fiber-optic sensors was also determined. The fiber-optic temperature sensor using Lophine provided a relatively broad range of temperature measurement with low sensitivity, whereas the fiber-optic temperature sensor using a thermochromic pigment offered a high sensitivity in a narrow range of temperature measurement.     

Linear and Nonlinear Optical Properties of Spherical Quantum Dots:Effects of Hydrogenic Impurity and Conduction Band Non-Parabolicity

Simultaneous effects of an on-center hydrogenic impurity and band edge non-parabolicity on intersubband optical absorption coefficients and refractive index changes of a typical GaAs/Al x Ga 1 x As spherical quantum dot are theoretically investigated,using the Luttinger-Kohn effective mass equation.So,electronic structure and optical properties of the system are studied by means of the matrix diagonalization technique and compact density matrix approach,respectively.Finally,effects of an impurity,band edge non-parabolicity,incident light intensity and the dot size on the linear,the third-order nonlinear and the total optical absorption coefficients and refractive index changes are investigated.Our results indicate that,the magnitudes of these optical quantities increase and their peaks shift to higher energies as the influences of the impurity and the band edge non-parabolicity are considered.Moreover,incident light intensity and the dot size have considerable effects on the optical absorption coefficients and refractive index changes.     

变色薄膜的紫外线辐照响应研究

 制备了含多芳氨基甲烷类化合物的高分子变色薄膜，经紫外线辐照后，这种薄膜随吸收剂量的不同由无色透明逐渐变为绿色，在可见光区主要吸收峰位于626 nm附近，光密度响应与辐照时间近似成线性关系。研究表明：该辐射变色薄膜变色响应随紫外线能量密度增加而增加；分次辐照能略微提高光密度响应；辐射变色薄膜响应受温度和湿度影响较大，在20～50 ℃温度范围、40%～60%相对湿度范围，响应基本稳定；卤代物添加剂可以大大提高辐射变色薄膜的响应灵敏度；受后辐照效应影响，辐照结束最初2 h内响应迅速增加，2 h后响应才基本稳定。     

Determination of the liquid crystals phase transition temperatures using optical rotation effect

Using optical rotation effect, a sensitive, simple optical analytical system is developed for determining the phase transition temperatures of liquid crystals (LCs). When a monochromatic polarized light passes through LCs sample and analyzer, the light intensity changes with temperature. Especially, during the phase transition process, the intensity varies greatly due to optical rotation effect. The variation of light intensity versus variation of temperature curve shows the phase transition temperatures of LCs clearly. The phase transition temperatures of three cholesteric liquid crystals (ChLCs) and a nematic liquid crystals (NLCs) were detected by this method, and compared with those of the differential scanning calorimetry (DSC) and polarized light microscope (PLM) methods.     

Disorder driven optical processes in nanocrystalline ZnO

A systematic study on the modification of optical properties in mechanically milled ZnO powder has been reported here. The average grain size of the powder becomes ～20 nm within 4 h of milling. Fluctuations of average grain size have been noticed at the initial stage of milling (within 15 min). Changes in grain morphology with milling have also been noticed in scanning electron micrographs of the samples. Room temperature optical absorption data shows a systematic red shift of absorption band edge (～3.25 eV). The band tail parameter (extracted from the optical absorption just below the band edge) follows a simple exponential relation with the inverse of the average grain size. Significant increase of the band tail parameter has been noticed at low grain size regime. It has been analyzed that high values of band tail parameter is a representative of V_Zn–V_O type divacancy clusters. Room temperature photoluminescence spectra show decrease (except for 120 min milling) of band edge emission intensity with increase of milling time. Subsequent decrease of sub-band edge emission is, however, less prominent. The variation of PL intensity ratio (intensity at band edge peak with that at 2.3 eV) follows simple exponential decrease with the increase of band tail parameter. This indeed shows that band edge emission in ZnO is related with the overall disorder in the system, not grain size induced only.     

Exact ellipsometric measurement of thickness and optical properties of a thin light-absorbing film without auxiliary measurements

It is shown, by exploring film optics, that the thickness and optical constants (refractive and absorption indices) of a light absorbing film can be determined from optical measurements alone made by an ellipsometer without the necessity of an auxiliary non-optical measurement. Use is made of an extra equation, relating the intensity of the reflected light to the three parameters pertaining to the film, in addition to the equations used in conventional ellipsometry. A surface film on cobalt in the state of electrochemically induced passivity was analyzed using this approach.