Zhang Ya-Nan, Wu Qilu, Peng Huijie, Zhao Yong
College of Information Science and Engineering, Northeastern University, Shenyang 110819, China.
Rev Sci Instrum. 2016 Dec;87(12):125002. doi: 10.1063/1.4971321.
A highly-sensitive and temperature-robust photonic crystal fiber (PCF) modal interferometer coated with Pd/WO film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. The sensor probe was fabricated by splicing two segments of a single mode fiber (SMF) with both ends of the PCF. Since the collapse of air holes in the PCF in the interfaces between SMF and PCF, a SMF-PCF-SMF interferometer structure was formed. The Pd/WO film was fabricated by sol-gel method and coated on the surface of the PCF by dip-coating method. When the Pd/WO film is exposed to hydrogen, both the length and cladding refractive index of the PCF would be changed, resulting in the resonant wavelength shift of the interferometer. Experimental results showed that the hydrogen measurement sensitivity of the proposed sensor can reach 0.109 pm/(μl/l) in the transformer oil, with the measurement range of 0-10 000 μl/l and response time less than 33 min. Besides, the proposed sensor was temperature-insensitive without any compensation process, easy to fabricate without any tapering, polishing, or etching process, low cost and quickly response without any oil-gas separation device. All these performances satisfy the actual need of real-time monitoring of dissolved hydrogen concentration in the transformer oil.
制备并研究了一种涂覆有Pd/WO薄膜的高灵敏度且温度稳定性好的光子晶体光纤（PCF）模态干涉仪，旨在实时监测变压器油中溶解氢的浓度。传感器探头通过将一段单模光纤（SMF）与光子晶体光纤的两端熔接而成。由于在单模光纤与光子晶体光纤的界面处光子晶体光纤中的气孔塌陷，形成了单模光纤-光子晶体光纤-单模光纤干涉仪结构。Pd/WO薄膜采用溶胶-凝胶法制备，并通过浸涂法涂覆在光子晶体光纤表面。当Pd/WO薄膜暴露于氢气中时，光子晶体光纤的长度和包层折射率都会发生变化，导致干涉仪的谐振波长偏移。实验结果表明，所提出的传感器在变压器油中的氢气测量灵敏度可达0.109 pm/(μl/l)，测量范围为0-10000 μl/l，响应时间小于33分钟。此外，所提出的传感器对温度不敏感，无需任何补偿过程，易于制造，无需任何拉锥、抛光或蚀刻过程，成本低，无需任何油气分离装置即可快速响应。所有这些性能均满足变压器油中溶解氢浓度实时监测的实际需求。
