Sampled fiber grating is a special superstructure fiber Bragg grating with a wide range of applications in many fields. In this work, based on drawing tower in-line fabrication system, a new preparation method of the sampled fiber grating is proposed and experimentally demonstrated. Experimental result shows that the obtained sampled fiber gratings possess dense reflection spectra, with a minimum reflection peak interval of only 0.09 nm. This method exhibits promising application prospect in the fabrication of the high-quality sampled fiber grating. On the other hand, the spectral characteristics of the sampled fiber grating are analyzed when the sub-grating is affected by the external physical quantities such as, in this paper, strain. Wavelength shift and intensity change in the reflection peak of the spectra indicate that the grating is affected differently by micro strains, due to the different spatial positions along the axis of the sampled fiber grating. This work is aimed at exploring the potential applications of the sampled fiber grating in quasi-distributed micro-area sensing with the millimeter level.

详细研究了n型AlGaN限制层与InGaN上波导对GaN基绿光激光器光场分布与电学特性的影响,结果表明:增加n型AlGaN限制层厚度或提高InGaN上波导中的铟组分可以明显抑制GaN基绿光激光器的光场泄漏,改善光场分布;相比In0.02Ga0.98N上波导,采用更高铟组分的In0.05Ga0.95N上波导可增加光场限制因子,改善绿光激光器的性能。综合调控n型限制层和上波导才能有效改善GaN基绿光激光器的光场分布,提高激光器的性能。

This paper reviews the work on huge capacity fiber-optic sensing network based on ultra-weak draw tower gratings developed at the National Engineering Laboratory for Fiber Optic Sensing Technology (NEL-FOST), Wuhan University of Technology, China. A versatile drawing tower grating sensor network based on ultra-weak fiber Bragg gratings (FBGs) is firstly proposed and demonstrated. The sensing network is interrogated with time- and wavelength-division multiplexing method, which is very promising for the large-scale sensing network.

This paper presents the testing results of three types of fire detectors: electrical heat sensing cable, optical fiber Raman temperature sensing detector, and optical fiber Bragg grating (FBG) temperature sensing detector, in two simulated fire scenes in a cable tunnel. In the small-scale fire with limited thermal radiation and no flame, the fire alarm only comes from the heat sensors which directly contact with the heat source. In the large-scale fire with about 5 ℃/min temperature rising speed within a 3-m span, the fire alarm response time of the fiber Raman sensor and FBG sensors was about 30 seconds. The test results can be further used for formulating regulation for early fire detection in cable tunnels.

介绍了在辐射环境中研究应用前景较好的几种主要的光纤传感器。结合已初步完成的布里渊传感器的相关实验，详细阐述了光纤布拉格光栅传感器、法布里珀罗光纤传感器、分布式光纤传感器和传输光纤在受到辐射时其性能发生变化的研究进展。简要分析了辐射对光纤传感器性能影响的几种不同观点，并分别展望了光纤传感器在辐射环境中的应用前景。

The combination of fiber optics with nanostructure technologies offers great potential for the realization of novel sensor concepts. Miniature optical fiber sensors based on the Fabry-Perot (F-P) structure are presented. The transducer deposited on the fiber end face is multilayer coating consisting of a stack of nanoporous dielectric TiO2 and MgF2 films of optical thickness \lambda/4, forming a F-P filter with a typical reflection minimum at about 1300-nm wavelength. The reversible adsorption and desorption of water molecules in the porous films depend on water vapor, which would shift the reflected minimum wavelength of the F-P filter. Therefore, the humidity sensing is correlated with the central wavelength change of the F-P filter. A 14-nm shift in central wavelength is observed when the relative humidity increases from 0 to 100%. The central wavelength response to relative humidity is 0.9969 in linearity, which means that the proposed F-P thin-film sensor is very promising as a relative humidity sensor.

提出一种双边缘结构对光纤光栅传感进行波长解调的方案，利用被测光谱通过不同光谱特性的滤波器时输出不同光强的比值确定被测光的波长．该系统在解调时不存在任何机械移动部分，比扫描式的解调方法测量速度更快，运行时更稳定、更精确．

A new type of fiber optic glucose biosensor based on fluorescence quenching has been designed and its properties have been studied. Glucose can be oxidized by oxygen when glucose oxidase are used as the catalyst, therefore, the concentration of glucose can be measured by detecting the consumption of oxygen. For the detection of oxygen concentration, the ruthenium(II) complex, Ru(bpy)3Cl2, were used as the fluorescence indicator and its fluorescence lifetime were detected by lock-in technology. The detecting range of the sensor is 50-500 mg/dl and its response time is 30 seconds, showing that this kind of sensors is possible to be used in clinical diagnosis and detection.