Li Lecheng, Xia Li, Xie Zhenhai, Liu Deming
Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Opt Express. 2012 May 7;20(10):11109-20. doi: 10.1364/OE.20.011109.
We propose and demonstrate a thinned fiber based Mach-Zehnder interferometer for multi-purpose sensing applications. The sensor head is formed by all-fiber in-line singlemode-multimode-thinned-singlemode (SMTS) fiber structure, only using the splicing method. The principle of operation relies on the effect that the thinned fiber cladding modes interference with the core mode by employing a multimode fiber as a mode coupler. Experimental results showed that the liquid refractive index information can be simultaneously provided from measuring the sensitivity of the liquid level. A 9.00 mm long thinned fiber sensor at a wavelength of 1538.7228 nm exhibits a water level sensitivity of -175.8 pm/mm, and refractive index sensitivity as high as -1868.42 (pm/mm)/RIU, respectively. The measuring method is novel, for the first time to our knowledge. In addition, it also demonstrates that by monitoring the wavelength shift, the sensor at a wavelength of 1566.4785 nm exhibits a refractive index sensitivity of -25.2935 nm/RIU, temperature sensitivity of 0.0615 nm/°C, and axial strain sensitivity of -2.99 pm/με, respectively. Moreover, the sensor fabrication process is very simple and cost effective.
我们提出并演示了一种基于变细光纤的马赫-曾德尔干涉仪，用于多用途传感应用。传感头由全光纤在线单模-多模-变细-单模（SMTS）光纤结构构成，仅使用熔接方法。其工作原理基于这样一种效应，即通过采用多模光纤作为模式耦合器，使变细光纤的包层模式与纤芯模式发生干涉。实验结果表明，通过测量液位灵敏度可以同时获取液体折射率信息。一根长度为9.00毫米、波长为1538.7228纳米的变细光纤传感器，其水位灵敏度为-175.8皮米/毫米，折射率灵敏度高达-1868.42（皮米/毫米）/RIU。据我们所知，该测量方法是新颖的。此外，这也表明，通过监测波长漂移，波长为1566.4785纳米的传感器的折射率灵敏度为-25.2935纳米/RIU，温度灵敏度为0.0615纳米/°C，轴向应变灵敏度为-2.99皮米/με。而且，该传感器的制造工艺非常简单且成本效益高。
