Common difference temperature compensation based fiber refractive index sensor through asymmetrical core-offset splicing

In this paper, an in-fiber Mach-Zehnder interferometer (MZI) is developed for refractive index (RI) sensing through core-offset splicing. In MZI, two ends of a section erbium-doped fiber are asymmetrically spliced with two pieces of single-mode fiber in order to get large contrast ratio of fringes. The comprehensive experimental measurements are then performed in terms of temperature and ambient RI. Owing to high sensitive consistency in temperature, a novel common difference compensation (CDC) method is introduced to achieve the self-elimination of cross-sensitivity. Thus the measurement error (∼1.2%) can be deleted by CDC and the corrected sensitivity (-74.22nm/RIU) is obtained without the crosstalk from temperature In addition, high working stabilities are demonstrated in the fabricated RI sensor in terms of wavelength (±0.02 nm) and intensity (±0.03 dB).