Hybrid tilted fiber grating based refractive index and liquid level sensing system

摘要

We report a refractive index (RI) and liquid level sensing system based on a hybrid grating structure comprising of a 45 and an 81 tilted fiber gratings (TFGs) that have been inscribed into a single mode fiber in series. In this structure, the 45 degrees-TFG is used as a polarizer to filter out the transverse electric (TE) component and enable the 81 degrees-TFG operating at single polarization for RI and level sensing. The experiment results show a lower temperature cross-sensitivity, only about 7.33 pm/degrees C, and a higher RI sensitivity, being around 180 nm/RIU at RI=1345 and 926 nm/RIU at RI=1.412 region, which are significantly improved in comparison with long period fiber gratings. The hybrid grating structure has also been applied as a liquid level sensor, showing 3.06 dB/mm linear peak ratio sensitivity. (C) 2015 Elsevier B.V. All rights reserved.