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Electrical and electronic engineering, Communication engineering and systems
Abstract—An all-fiber 1 refractive index (RI) sensor with a 2 simple configuration of periodical tapers is proposed and inves3 tigated experimentally. The proposed fiber RI sensor consists of 4 a small core fiber sandwiched between two standard singlemode 5 fibers, with tapers periodically fabricated along the small core 6 fiber using a focused CO2 laser beam. Such a structure can be 7 used for RI sensing by measuring the dip wavelength shift of 8 the multimode interference within the small core fiber cladding. 9 An average sensitivity of 226.6 nm/RIU (RI Unit) has been 10 experimentally achieved in the RI range from 1.33 to 1.38. The 11 refractometer is sensitive to temperature and an experimental 12 investigation of this sensitivity is presented. It is found that the 13 peak shift response has a linear variation with temperature; 14 therefore, temperature dependence can be mitigated by a suitable 15 RI correction process. The proposed RI sensor benefits from 16 simplicity and low cost and achieves a competitive sensitivity 17 compared with other existing fiber-optic sensors.
Wang, P., Brambilla, G., Ding, M., Lee, T., Bo, L., Semenova, Y., Wu, Q, Farrell, G.: Enhanced Refractometer Based on Periodically Tapered Small Core Singlemode Fiber. IEEE Sensors Journal, 2012, In Press. doi:10.1109/JSEN.2012.2216865