Intensity modulated refractive index sensor based on optical fiber Michelson interferometer

We demonstrated a refractive index (RI) sensor based on optical fiber Michelson interferometer (MI), which was fabricated by splicing a section of thin core fiber (TCF) to a standard single mode fiber witha core offset. Experimentally, such a MI-based RI sensor with a core offset of 8 mu m and a TCF length of 3 mm exhibits a high resolution of 4.9 x 10(-6) RIU and sensitivity of -202.46 dB/RIU, which is two or three times higher than that of intensity-modulated RI sensors reported previously. In contrast, our MI-based RI sensor is insensitive to temperature, thus overcoming the cross-sensitivity problem between surrounding RI and temperature. Moreover, intensity modulation, rather than wavelength modulation, was used in the proposed MI-based RI sensor, and the sensor also has the advantages of compact size (8 mm), simple structure, easy fabrication, and good repeatability. (C) 2014 Published by Elsevier B.V.