Photonic crystal fiber modal interferometer with Pd/WO3 coating for real-time monitoring of dissolved hydrogen concentration in transformer oil

A highly-sensitive and temperature-robustphotonic crystal fiber(PCF) modalinterferometer coated with Pd/WO3film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. Thesensor probe was fabricated by splicing two segments of a single mode fiber(SMF) with both ends of thePCF. Since the collapse of air holes in thePCF in the interfaces betweenSMF andPCF, a SMF-PCF-SMFinterferometer structure was formed. The Pd/WO3film was fabricated by sol-gel method and coated on the surface of thePCF by dip-coating method. When the Pd/WO3film is exposed to hydrogen, both the length andcladding refractive index of thePCF would be changed, resulting in the resonant wavelength shift of theinterferometer. Experimental results showed that the hydrogenmeasurement sensitivity of the proposedsensor can reach 0.109 pm/( μl/l) in the transformer oil, with themeasurement range of 0 –10 000μl/l and response time less than 33 min. Besides, the proposedsensor 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.

Source: Review of Scientific Instruments - December 7, 2016 Category: Physics Authors: Ya-nan Zhang, Qilu Wu, Huijie Peng and Yong Zhao Source Type: research