High-sensitivity long-period fiber grating sensor with SAN/cryptophane A for coal mine gas detection

A high-sensitivity long-period fiber grating （LPFG） methane sensor that contains a compact and uniform styrene-acrylonitrile （SAN）/cryptophane A nanofilm is presented. The sensor is prepared by using an automatic dip-coater in a solution of cryptophane A, SAN resin dissolved in ortho-dichlorobenzene, a low- volatile solvent. The effect of film thickness on the LPFG＇s resonant wavelength is thoroughly investigated. The optimum sensor among the three LPFGs with different film thicknesses is directly used to detect the methane concentration in a coal mine gas sample. The results indicate that the sensors with film thicknesses of 484 to 564 nm exhibit a redshifted resonant wavelength when the methane concentration is increased from 0% to 3.5% （vol）. The data demonstrates that the sensor with a film thickness of 484 nm has remarkable sensitivity （~0.633 nm%-X）, and its detection limit can reach 0.2%. The methane concentrations determined by our sensor are consistent with those obtained by gas chromatography.     

亚微米级Y3Al5O12∶Ce3+荧光粉的共沉淀法合成、表征及光致发光

以金属硝酸盐为原料,使用NH3·H2O-NH4HCO3混合沉淀剂,开展了以反滴化学共沉淀方式和两步煅烧法合成掺铈的钇铝石榴石(Y3Al5O12∶Ce3 )黄色荧光粉研究。采用DTA-TGA和XRD研究共沉淀法制备的前驱体粉末热分解与钇铝石榴石晶相形成过程,通过荧光光谱和SEM研究荧光粉光致发光及添加剂对其发光和形貌影响规律。结果表明,采用化学共沉淀法合成温度比传统高温固相法降低300℃以上;荧光粉粒径0.3～1μm,颗粒规则呈类球状;468nm激发下荧光粉发射峰为532nm;煅烧阶段添加氟化物,可使荧光粉的发射强度等发光特性明显提高,对控制Y3Al5O12∶Ce3 荧光粉的形貌有显著作用;与蓝光LED芯片封装后形成的白光LED色温Tc为5571K,光效率为45lm·W-1,显色指数Ra为79.9,色坐标为(0.3308,0.3476)。     

(Ca1-x-yLuy)MoO4∶xEu3+红色荧光粉的化学共沉淀合成与光致发光

使用NH4HCO3-NH3.H2O混合沉淀剂,采用化学共沉淀法合成(Ca1-x-yLuy)MoO4:xEu3+红色荧光粉,通过XRD、EDS、荧光光谱和CIE色度图研究该荧光粉的晶体结构、成分组成及发光性能。结果表明,实验按照理论化学计量比成功合成了(Ca1-x-yLuy)MoO4:xEu3+红色荧光粉,该荧光粉为CaMoO4白钨矿结构;(Ca1-x-yLuy)MoO4:xEu3+具有7F0→5L6(394 nm)和7F0→5D2(465 nm)的强电子吸收,且在613 nm处可发射高强度红光,其色坐标为(0.666 5,0.332 9),明显优于传统的Y2O2S:Eu3+红色荧光粉;此外,当Lu含量为30mol%时,荧光粉发光强度最佳。     

Optical fiber methane sensor based on SAN film containing cryptophane-E-（OEt）_6

A novel long-period fiber grating (LPFG) film methane sensor is designed and applied successfully. The sensor is constructed by depositing a thin styrene-acrylonitrile (SAN) film containing the new compound cryptophane-E-(OEt)6 onto the cladding surface of the LPFG. This film is sensitive to methane gas. Methane causes a change in the refractive index of the sensing film, which can be measured by shifting the resonance wavelength. Experimental results show that the resonant wavelength shifts to the longer wavelength, with increasing methane concentration at a range of 0.0%-3.5% (v/v). A linear relationship is obtained within the test range. Detection limit is estimated at 0.2%, and response time is 60 s. No significant interference is detected from dry air, O2 , CO, CO2 , and H2 . This novel methane sensing material has great application potential due to its advantages.     

基于掺铒光纤中动态粒子数光栅的振动检测

根据动态粒子数光栅形成机理,设计了一种线性双波混频结构的光纤系统。系统中,1490nm波长分布式反馈(DFB)激光器光源发出的连续激光,通过环形器进入一根3m长掺铒光纤作为注入光,被与掺铒光纤另一端光学耦合的压电振动镜反射后形成反射光。掺铒光纤中注入光与后向传播的反射光干涉形成驻波场,通过空间烧孔效应沿光纤纵向形成动态粒子数光栅。压电振动镜对反射光波进行相位调制时,环形器反射端口输出的双波混频(TWM)信号可视作输出光波的强度调制。实验中通过此双波混频系统对压电换能器产生的机械振动进行检测,结果表明:光纤双波混频检测系统具有良好的动态响应特性,能够测量50Hz~10kHz的振动信号,采集到的输出信号频率与压电驱动信号频率很好地吻合。     

YAG:Ce荧光粉的喷雾干燥热解二步法合成与表征

采用喷雾干燥热解二步法合成Y3A15O12：Ce^3＋（YAG：Ce）荧光粉，利用XRD，FT-IR，SEM和荧光光谱等方法分析不同热解温度下YAG：Ce荧光粉的结构变化，评价柠檬酸和助熔剂NaF对荧光粉光致发光性能的影响规律。结果表明，热解温度为1100℃时的荧光粉中不含YAP等过渡相，其结晶度随热解温度增加而提高；加入柠檬酸能显著改善产物形态，为典型球形颗粒，且以浓度0．08mol·L^-1为最佳；加入NaF可降低YAG相形成温度，提高荧光粉的发光强度，其最优值为0．0075mol·L^-1；与蓝光LED芯片封装形成白光LED的显色指数Ra为85．6，色坐标为（0．3184，0．3419），色温Tc为6165K。     

基于半导体光纤环形激光器的光纤布喇格光栅动态应变传感系统

提出一种能实时识别外来撞击声发射信号的被动结构健康监测系统.此系统使用基于半导体光放大器的光纤布喇格光栅传感系统监测高频动态应变,动态应变引起的光栅反射谱波长移动转化为相位变化,并被迈克尔逊干涉仪解调.在迈克尔逊干涉解调仪中,使用PID控制器补偿由温度和大的准静态应变引起的低频漂移.对光程差和布喇格光栅光谱线宽等参量进行了分析和优化.利用该解调系统成功地对金属板受到撞击时激发的声发射进行了感测,可获取的动态应变信号频率高达197kHz.     

亚微米级Y3Al5O12:Ce3+荧光粉的共沉淀法合成、表征及光致发光

以金属硝酸盐为原料,使用NH3·H2O-NH4HCO3混合沉淀剂,开展了以反滴化学共沉淀方式和两步煅烧法合成掺铈的钇铝石榴石(Y3Al5O12Ce3+)黄色荧光粉研究.采用DTA-TGA和XRD研究共沉淀法制备的前驱体粉末热分解与钇铝石榴石晶相形成过程,通过荧光光谱和SEM研究荧光粉光致发光及添加剂对其发光和形貌影响规律.结果表明,采用化学共沉淀法合成温度比传统高温固相法降低300 ℃以上;荧光粉粒径0.3～1 μm,颗粒规则呈类球状;468 nm激发下荧光粉发射峰为532 nm;煅烧阶段添加氟化物,可使荧光粉的发射强度等发光特性明显提高,对控制Y3Al5O12Ce3+荧光粉的形貌有显著作用;与蓝光LED芯片封装后形成的白光LED色温Tc为5571 K,光效率为45 lm·W-1,显色指数Ra为79.9,色坐标为(0.3308,0.3476).