Liu Xianjin, Zhang Xudong, Yang Jiuru, Du Xiliang
Appl Opt. 2019 Sep 20;58(27):7582-7587. doi: 10.1364/AO.58.007582.
In this paper, an in-line Mach-Zehnder interferometer embedded in a fiber Bragg grating (FBG) is fabricated by a tiny offset-core splicing technique and inserted into a fiber ring laser to effectively improve the detection limit and discrimination of sensing. Through fine power adjustment, the stable operation of dual-wavelength lasing is completed in a single FBG for the first time to our knowledge, and simultaneous measurement of refractive index (RI) and ambient temperature is achieved with high discrimination due to the RI immunity of the FBG. The experimental results indicate that the sensitivities of RI and temperature are -30.57 nm/RIU and 131.1 pm/°C, respectively, with very low intensity drift. Furthermore, the over 20 times improvement of the RI detection limit is obtained owing to the large extinction ratio (>30 dB) and small linewidth (≤0.13 nm).
在本文中，通过微小偏心纤芯熔接技术制作了一种嵌入光纤布拉格光栅（FBG）的在线马赫-曾德尔干涉仪，并将其插入光纤环形激光器中，以有效提高传感的检测极限和分辨率。据我们所知，通过精细的功率调节，首次在单个FBG中实现了双波长激光的稳定运行，并且由于FBG的折射率免疫特性，实现了高分辨率的折射率（RI）和环境温度的同时测量。实验结果表明，RI和温度的灵敏度分别为-30.57 nm/RIU和131.1 pm/°C，强度漂移非常低。此外，由于大消光比（>30 dB）和小线宽（≤0.13 nm），RI检测极限提高了20倍以上。
